Symplectic realization of electric charge in fields of monopole distributions

Wed 31 Oct 2018 12:28:51 KRAT

We construct a symplectic realization of the twisted Poisson structure on the phase space of an electric charge in the background of an arbitrary smooth magnetic monopole density in three dimensions. We use the extended phase space variables to study the classical and quantum dynamics of charged particles in arbitrary magnetic fields by constructing a suitable Hamiltonian that reproduces the Lorentz force law for the physical degrees of freedom. In the source-free case the auxiliary variables can be eliminated via Hamiltonian reduction, while for nonzero monopole densities they are necessary for a consistent formulation and are related to the extra degrees of freedom usually required in the Hamiltonian description of dissipative systems. We obtain new perspectives on the dynamics of dyons and motion in the field of a Dirac monopole, which can be formulated without Dirac strings. We compare our associative phase space formalism with the approach based on nonassociative quantum mechanics, reproducing extended versions of the characteristic translation group three-cocycles and minimal momentum space volumes, and prove that the two approaches are formally equivalent. We also comment on the implications of our symplectic realization in the dual framework of nongeometric string theory and double field theory.

Index theorems and domain walls

Wed 31 Oct 2018 12:28:50 KRAT

The Atiyah-Patodi-Singer (APS) index theorem relates the index of a Dirac operator to an integral of the Pontryagin density in the bulk (which is equal to global chiral anomaly) and an η invariant on the boundary (which defines the parity anomaly). We show that the APS index theorem holds for configurations with domain walls that are defined as surfaces where background gauge fields have discontinuities.

О соотношении категорий to lekton в философии стоиков и Sinn в семантической теории Г. Фреге: вопрос об их эпистемологическом статусе

Wed 31 Oct 2018 12:21:43 KRAT

В статье проводится сравнительный анализ категории стоиков to lekton и категории Г. Фреге Sinn. Эксплицируются некоторые формальные черты этих категорий, которые демонстрируют сходство логических теорий стоиков и Фреге. Показано, что понятие полного lekton (axiōma) в учении стоиков имеет такую же структуру, как и понятие мысли (Gedanke) в семантической теории Фреге. Однако формальное сходство между lekton и Sinn не означает доктринального сходства с точки зрения эпистемологического статуса этих категорий.

Chiral magnetic effect in the presence of an external axial-vector field

Wed 31 Oct 2018 11:18:55 KRAT

We study the excitation of the electric current of chiral fermions along the external magnetic field, known as the chiral magnetic effect, in the presence of the background axial-vector field. The calculation of the current is based on the exact solution of the Dirac equation for these fermions accounting for the external fields. First, this solution was obtained for massive particles and, then, we consider the chiral limit, which is used in the anomalous current computation. We obtain that, in this situation, the anomalous current does not contain the direct contribution of the axial-vector field. This result is compared with findings of other authors.

Asymmetric cryptosystems on Boolean functions

Wed 27 Jun 2018 10:36:24 KRAT

Here, we define an asymmetric substitution cryptosystem combining both a public key cipher and a signature scheme with the functional keys. A public key in the cryptosystem is a vector Boolean function f(x1,... ,xn) of a dimension n. This function is obtained by permutation and negation operations on variables and coordinate functions of a bijective vector Boolean function g(x1,... ,xn) == (g1(x1,... ,xn),... ,gn(x1,... ,xn)). The function g is called a generating function of the cryptosystem. For each i e {1,..., n}, its coordinate function g^(x1,..., xn) is assumed to be specified in a constructive way and to have a polynomial (in n) complexity. A private key of the cryptosystem is the function f-1, that is, the inverse of f. The existence of f-1 follows from the bijectiveness of g and preserving this property by permutation and negation operations. Function g and its coordinates g1,...,gn are public parameters of the cryptosystem. (A variant of the cryptosystem allows to include them into the private key). Of course, the permutation and negation operations by which a public key is computed from the generating function must be secret as private exponents in RSA and ElGamal cryptosystems. A block P of a plaintext is encrypted to a block C of a ciphertext by the rule C = f (P), and C is decrypted to P by the rule P = f-1(C). A signature on a message M is computed as S = f-1(P), and its validation is proved by verifying the equality M = f (S). This cryptosystem is believed to resist classical and quantum computers attacks. Its security is based on the difficulty of inverting large bijective vector Boolean functions. Cryptanalysis of the cryptosystem shows that its computational complexity can reach the value O(n!2n).

On frequency estimation for partially observed system with small noises in state and observation equations

Wed 26 Feb 2020 09:08:52 KRAT

We consider the problem of frequency estimation of the periodic signal multiplied by a Gaussian process (Ornstein-Uhlenbeck) and observed in the presence of the white Gaussian noise. We demonstrate the consistency and asymptotic normality of the maximum likelihood and Bayesian estimators in the sense of the small noise asymptotics. The model of observations is a linear nonhomogeneous partially observed system and the construction of the estimators is based on the Kalman-Bucy filtration equations. For the study of the properties of the estimators, we apply the techniques introduced by Ibragimov and Has'minskii.

Phase control of Schwinger pair production by colliding laser pulses

Wed 25 Nov 2020 11:21:13 KRAT

We study the Schwinger electron-positron pair production by a strong electromagnetic field of two colliding e-polarized laser pulses with a relative phase shift . The spatiotemporal distribution of created pairs is very sensitive to this phase shift and to polarization of the pulses. We study this dependence in detail and demonstrate how it can be explained in terms of the underlying invariant field structure of the counterpropagating focused pulses.

Unitary quantization and para-Fermi statistics of order 2

Wed 25 Nov 2020 11:21:09 KRAT

A connection between a unitary quantization scheme and para-Fermi statistics of order 2 is considered. An appropriate extension of Green's ansatz is suggested. This extension allows one to transform bilinear and trilinear commutation relations for the annihilation and creation operators of two different para-Fermi fields ϕa and ϕb into identity. The way of incorporating para-Grassmann numbers ξk into a general scheme of uniquantization is also offered. For parastatistics of order 2 a new fact is revealed, namely, the trilinear relations containing both the para-Grassmann variables ξk and the field operators ak, bm under a certain invertible mapping go over into the unitary equivalent relations, where commutators are replaced by anticommutators and vice versa. It is shown that the consequence of this circumstance is the existence of two alternative definitions of the coherent state for para-Fermi oscillators. The Klein transformation for Green's components of the operators ak, bm is constructed in an explicit form that enables us to reduce the initial commutation rules for the components to the normal commutation relations of ordinary Fermi fields. A nontrivial connection between trilinear commutation relations of the unitary quantization scheme and so-called Lie-supertriple system is analysed. A brief discussion of the possibility of embedding the Duffin-Kemmer-Petiau theory into the unitary quantization scheme is provided.

Optical properties of β-BBO and potential for THz applications

Wed 25 Nov 2020 11:21:04 KRAT

The anisotropy of optical properties of high quality beta barium borate crystal (β-BaB2O4, β-BBO) was studied in the main transparency window by using classic spectroscopic methods and in the range of 0.2 – 2 THz by using THz time-domain spectroscopy. β-BBO crystals were grown by the top-seeded solution technique in a highly resistive furnace with a heat field of 3-fold axis symmetry. At room temperature (RT), absorption coefficient in the maximal transparency window in grown crystals did not exceed 0.05 cm-1. Strong absorption anisotropy was observed in 3 – 5 μm and the THz range. At 1 THz absorption coefficients for e and o wave were, respectively, 7 cm-1 and 21 cm-1 at RT; 2 cm-1 and 10 cm-1 at 81 K. At the most attractive for out-of-door applications range < 0.4 THz the absorption coefficient is found to be very low: below 0.2 cm-1 at RT and 1 cm-1 at 81 K. Refractive indices dispersions measured by THz-TDS were approximated in the form of Sellmeier equations. Birefringence is found quite large for phase matched difference frequency generation (DFG) or down-conversion into the THz range (THz-DFG) under near IR pump at RT and 81 K. Type II (oe-o and eo-o), and type I (ee-e) three wave interactions can be realized at RT. THz-DFG of Nd:YAG laser and KTP OPO can be realized by type II (oe-o) three-wave interaction. For selected spectral ranges of femtosecond Ti:Sapphire laser efficient phase matched and group velocity matched optical rectification can be realized by another two types of three wave interactions. Accounting other well-known attractive physical properties of β-BBO crystal, wide application in THz technique can be forecasted.

Математическое моделирование движения сферической частицы по наклонной поверхности в сдвиговом потоке

Wed 16 May 2018 11:18:25 KRAT

Проведено исследование движения сферической частицы по наклонной поверхности, обдуваемой сдвиговым потоком. Проанализированы различные режимы движения частицы в потоке: качение, скольжение, пробуксовка. Исследование движения по наклонной поверхности, обдуваемой воздушным потоком, показывает, что скорость центра масс частиц увеличивается с увеличением ее диаметра, при этом скорость частиц быстро достигает стационарного значения. Изменение угловой скорости ω характеризуется на начальном этапе резким ее возрастанием, после чего качение частицы происходит с постоянной угловой скоростью. Для малых размеров частицы ее движение на начальном участке характеризуется качением без скольжения, однако затем переходит в режим проскальзывания.

On an extremal problem for nonoverlapping domains

Wed 16 May 2018 11:04:44 KRAT

The paper considers the problem of finding the range of the functional ( ) I=J(f z0,f(z0),F(ζ0),F(ζ0)) defined on the class M of functions pairs (f (z),F(ζ)) that are univalent in the system of the disk and the interior of the disk, using the method of internal variations. We establish that the range of this functional is bounded by the curve whose equation is written in terms of elliptic integrals, depending on the parameters of the functional I.

Ранг формальной матрицы. Система формальных линейных уравнений. Делители нуля

Wed 16 May 2018 11:04:27 KRAT

Вводится понятие ранга формальной матрицы со значениями в данном коммутативном кольце и рассматриваются системы формальных линейных уравнений. Приводятся некоторые свойства ранга. Получены необходимые и достаточные условия существования решения однородной системы формальных линейных уравнений. Находится условие, при котором формальная матрица будет левым или правым делителем нуля.

Gravitational parity anomaly with and without boundaries

Wed 16 May 2018 10:22:21 KRAT

In this paper we consider gravitational parity anomaly in three and four dimensions. We start with a re-computation of this anomaly on a 3D manifold without boundaries and with a critical comparison of our results to the previous calculations. Then we compute the anomaly on 4D manifolds with boundaries with local bag boundary conditions. We find, that gravitational parity anomaly is localized on the boundary and contains a gravitational Chern-Simons terms together with a term depending of the extrinsic curvature. We also discuss the main properties of the anomaly, as the conformal invariance, relations between 3D and 4D anomalies, etc.

Непараметрическое оценивание характеристик функции надежности с учетом дополнительной информации

Wed 06 Nov 2019 16:10:32 KRAT

Предлагаются оценки характеристик функции надежности невосстанавливаемого элемента с учетом дополнительной информации о законе распределения времени отказа в условиях непараметрической априорной неопределенности. Строятся оптимальные по минимуму среднеквадратической ошибки оценки и адаптивные к оптимальным оценки, находятся их предельные распределения. Приводятся иллюстративные примеры.

Мировой лист массивной спиновой частицы в d=4 пространстве Минковского

Wed 06 Nov 2019 16:02:28 KRAT

Рассматривается геометрическая модель массивной спиновой частицы, чье квантование соответствует унитарному неприводимому представлению группы Пуанкаре. Показано, что класс калибровочно-эквивалентных траекторий частицы образует цилиндрическую поверхность в d = 4 пространстве Минковского. Исходя из того, что траектории частицы являются цилиндрическими линиями, получены уравнения движения частицы по мировому листу по времениподобным или изотропным траекториям.

Численный анализ турбулентных режимов сопряженного конвективно-радиационного теплопереноса в замкнутой области со стеклянной стенкой

Wed 06 Nov 2019 15:27:30 KRAT

Проведено математическое моделирование нестационарной турбулентной термогравитационной конвекции и теплового поверхностного излучения в замкнутой полости с твердыми теплопроводными стенками конечной толщины при наличии источника энергии постоянной температуры. Процесс переноса импульса, массы и энергии описывался системой дифференциальных уравнений в переменных «функция тока – температура – завихренность». Краевая задача решена методом конечных разностей на неравномерной сетке. В качестве замыкающей модели турбулентности использовалась стандартная k  модель. Проанализировано влияние степени черноты ограждающих поверхностей и фактора нестационарности на режимы течения и теплоперенос. В результате проведенных исследований получены распределения как локальных (изолинии функции тока и температуры), так и интегральных (средние радиационное и конвективное числа Нуссельта) характеристик. Показано, что увеличение степени черноты ограждающих поверхностей проявляется в изменении структуры течения и интенсификации теплопереноса.

Статистический анализ развития физической культуры и спорта г. о. Тольятти

Wed 06 Jun 2018 13:45:51 KRAT

Анализируются статистические данные отчета Департамента физической культуры и спорта г.о. Тольятти. Исследуются данные общей численности населения и сопоставляются с количеством регулярно занимающихся физической культурой и спортом и уровнем обеспеченности спортивными сооружениями (по единовременной пропускной способности). Анализируется состояние кадрового потенциала, уровень профессионального образования специалистов.

Новые семейства мультипликативных циркулянтных сетей

Wed 03 Oct 2018 16:01:15 KRAT

Рассматривается задача оптимизации циркулянтных сетей, состоящая в максимизации числа вершин при заданных степени и диаметре графа. На основе изучения мультипликативных циркулянтов с образующими, представленными в виде степеней нечётных чисел t @ 5, построены два новых семейства мультипликативных циркулянтов нечётных размерностей k @ 3 и диаметров d = 0 mod k и чётных размерностей k @ 4 и диаметров d = 0 mod k и d = 0 mod k/2, графы которых превосходят по числу вершин при тех же размерностях и диаметрах известные семейства мультипликативных циркулянтов.

О числе однородных невырожденных p-ичных функций заданной степени

Wed 03 Oct 2018 15:54:09 KRAT

Пусть p — простое число, F = GF(p), Vn — n-мерное векторное пространство над F , е — базис пространства Vn. Пусть также р : Vn ^ F . Функция р называется e-однородной, если р(х) = nv,e(x) для всех х £ Vn, где nv,e — однородный многочлен от n переменных над F , имеющий степень не более p — 1 по каждой переменной, а x — набор координат вектора х в базисе е. Функция р называется невырожденной, если deg р @ 1 и deg dvр = (deg р) — 1 для любого v £ Vn {0}, где (dvр )(х ) = р (х + v) — р(х) для всех v,x £ Vn. Получена формула для числа HNp(n, d) е-однородных невырожденных функций р : Vn ^ F , имеющих степень d (это число не зависит от е), а именно: если n @ 1 и d £ {1 ,... ,n(p — 1)}, n (k ,fn-k

Mathematical methods in solutions of the problems presented at the Third International Students' Olympiad in Cryptography

Tue 26 Jun 2018 10:06:23 KRAT

The mathematical problems, presented at the Third International Students’ Olympiad in Cryptography NSUCRYPTO’2016, and their solutions are considered. They are related to the construction of algebraic immune vectorial Boolean functions and big Fermat numbers, the secrete sharing schemes and pseudorandom binary sequences, biometric cryptosystems and the blockchain technology, etc. Two open problems in mathematical cryptography are also discussed and a solution for one of them proposed by a participant during the Olympiad is described. It was the first time in the Olympiad history. The problem is the following: construct F : ^ with maximum possible component algebraic immunity 3 or prove that it does not exist. Alexey Udovenko from University of Luxembourg has found such a function.

Класс сбалансированных алгебраических пороговых функций

Tue 26 Jun 2018 10:06:12 KRAT

Предложен подход к построению класса сбалансированных алгебраических пороговых функций (АПФ). Функция k-значной логики f называется АПФ, если существуют целочисленные наборы c = (c0, ci,..., cn), b = (Ь0,Ъ,..., bk) и натуральный модуль m, такие, что f(x1 , x2,...,xn) = a, если и только если b« @ rm(co + CiXi + С2Х2 + ■ ■ ■ + CnXn) < Ъа+1 для любого а е Qk, где rm(x) — функция приведения числа x по модулю m. Тройку (c; b; m) будем называть структурой функции f. Центральным результатом работы является построенный класс сбалансированных АПФ, а именно: если для АПФ f, заданной структурой ((co, ci, С2,..., Cn); (0,p, 2p,..., kp); kp) = (c, b, m), существует c = pq и (q, k) = 1, то такая функция сбалансированная. Сбалансированные функции данного класса могут быть использованы в качестве координатных функций подстановок.

Формирование личного и социального капитала студентами из Таджикистана в Томске: возможности и барьеры

Tue 19 Mar 2019 20:08:19 KRAT

Анализируется процесс социализации студентов из Таджикистана в университетах Томска. Формулируется тезис о том, что накопление личностного и социального капитала дает возможность молодым мигрантам постепенно вливаться в состав российской гражданской нации. Анализируются барьеры, препятствующие реализации этого процесса. Методологическая основа исследования – теория «социального поля» П. Бурдьё и тезис немецкого социолога Г. Хайнзона о «Youth Bulge» – «молодежном пузыре». Эмпирическая основа – материалы индивидуальных глубинных интервью со студентами из Таджикистана и другими акторами, включенными в рассматриваемый процесс.

Асимптотический анализ многофазной бесконечнолинейной ресурсной системы массового обслуживания с входящим MMPP потоком

Tue 19 Mar 2019 19:19:22 KRAT

Рассматривается бесконечнолинейная ресурсная система массового обслуживания MMPP/(GI/∞)M. Решается задача исследования 2M-мерного процесса чисел занятых приборов и суммарных объемов занятого ресурса на фазах системы в стационарном режиме функционирования. С помощью метода асимптотического анализа получена асимптотическая характеристическая функция распределения вероятностей исследуемого многомерного процесса, которая совпадает с характеристической функцией многомерного гауссовского распределения.

The hedging strategy for Asian option

Tue 19 Mar 2019 18:02:18 KRAT

The article deals with the problem of portfolio investment in the Black-Scholes model with several risky assets. The hedging strategy for Asian option is found using the martingale method. The analytical properties (differentiability) of the densities of exponential random variables are studied.

Experimental and theoretical investigations of the near-ground propagation of acoustic radiation in the atmosphere

Tue 14 May 2019 09:38:20 KRAT

Near-ground propagation of monochromatic acoustic radiation at frequencies of 300, 1000, 2000, and 3150 Hz along atmospheric paths up to 100 m long is investigated experimentally and theoretically depending on altitudes of the acoustic source and receiver. The experiment was carried out at the experimental site of the Institute of Monitoring of Climatic and Ecological Systems (IMCES) using a specially developed setup. The dependence of the recorded sound pressure level on the propagation path length and initial signal power is analyzed. The theoretical analysis is performed by the Monte Carlo method using the local estimation algorithm developed by the authors. The comparison of the experimental and theoretical results shows their satisfactory agreement, which indicates the effectiveness of the proposed algorithm and its applicability to predicting the near-ground sound propagation.

Combination of inclusive and differential t¯t charge asymmetry measurements using ATLAS and CMS data at √s = 7 and 8 TeV

Tue 11 Jun 2019 15:32:30 KRAT

Search for pair production of up-type vector-like quarks and for four-top-quark events in final states with multiple b-jets with the ATLAS detector

Tue 05 Nov 2019 15:32:21 KRAT

A search for pair production of up-type vector-like quarks (T) with a significant

Search for the decay of the Higgs boson to charm quarks with the ATLAS experiment

Thu 20 Jun 2019 10:52:52 KRAT

Measurements of differential cross sections of top quark pair production in association with jets in pp collisions at √s = 13 TeV using the ATLAS detector

Thu 20 Jun 2019 10:52:46 KRAT

Search for B−L R-parity-violating top squarks in √s=13 TeV pp collisions with the ATLAS experiment

Thu 20 Jun 2019 10:52:42 KRAT

A search is presented for the direct pair production of the stop, the supersymmetric partner of the top quark, that decays through an R-parity-violating coupling to a final state with two leptons and two jets, at least one of which is identified as a b-jet. The data set corresponds to an integrated luminosity of 36.1 fb−1 of proton-proton collisions at a center-of-mass energy of √s=13 TeV, collected in 2015 and 2016 by the ATLAS detector at the LHC. No significant excess is observed over the Standard Model background, and exclusion limits are set on stop pair production at a 95% confidence level. Lower limits on the stop mass are set between 600 GeV and 1.5 TeV for branching ratios above 10% for decays to an electron or muon and a b-quark.

Search for supersymmetry in final states with charm jets and missing transverse momentum in 13 TeV pp collisions with the ATLAS detector

Thu 20 Jun 2019 10:52:39 KRAT

Search for the Higgs boson produced in association with a vector boson and decaying into two spin-zero particles in the H → aa → 4b channel in pp collisions at √s=13 TeV with the ATLAS detector

Thu 20 Jun 2019 10:52:33 KRAT

Measurements of t¯t differential cross-sections of highly boosted top quarks decaying to all-hadronic final states in pp collisions at √s=13 TeV using the ATLAS detector

Thu 20 Jun 2019 10:52:32 KRAT

Measurements are made of differential cross-sections of highly boosted pair-produced top quarks as a function of top-quark and t¯t system kinematic observables using proton-proton collisions at a center-of-mass energy of √s=13 TeV. The data set corresponds to an integrated luminosity of 36.1 fb−1, recorded in 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. Events with two large-radius jets in the final state, one with transverse momentum pT>500 GeV and a second with pT>350 GeV, are used for the measurement. The top-quark candidates are separated from the multijet background using jet substructure information and association with a b-tagged jet. The measured spectra are corrected for detector effects to a particle-level fiducial phase space and a parton-level limited phase space, and are compared to several Monte Carlo simulations by means of calculated χ2 values. The cross-section for t¯t production in the fiducial phase-space region is 292±7(stat)±71(syst) fb, to be compared to the theoretical prediction of 384±36 fb.

Search for a structure in the B0sπ± invariant mass spectrum with the ATLAS experiment

Thu 20 Jun 2019 10:38:53 KRAT

Search for high-mass resonances decaying to τν in pp collisions at √s=13 TeV with the ATLAS detector

Thu 20 Jun 2019 10:38:40 KRAT

Probing the quantum interference between singly and doubly resonant top-quark production in pp collisions at √s=13 TeV with the ATLAS detector

Thu 20 Jun 2019 09:42:53 KRAT

This Letter presents a normalized differential cross-section measurement in a fiducial phase-space region where interference effects between top-quark pair production and associated production of a single top quark with a W boson and a b-quark are significant. Events with exactly two leptons (ee, μμ, or eμ) and two b-tagged jets that satisfy a multiparticle invariant mass requirement are selected from 36.1 fb−1 of proton-proton collision data taken at √s=13 TeV with the ATLAS detector at the LHC in 2015 and 2016. The results are compared with predictions from simulations using various strategies for the interference. The standard prescriptions for interference modeling are significantly different from each other but are within 2σ of the data. State-of-the-art predictions that naturally incorporate interference effects provide the best description of the data in the measured region of phase space most sensitive to these effects. These results provide an important constraint on interference models and will guide future model development and tuning.

ZZ → ℓ+ℓ-ℓ'+ℓ' − cross-section measurements and search for anomalous triple gauge couplings in 13 TeV pp collisions with the ATLAS detector

Thu 20 Jun 2019 09:42:50 KRAT

Measurements of ZZ production in the ℓ+ℓ−ℓ'+ℓ'− channel in proton–proton collisions at 13 TeV center-of-mass energy at the Large Hadron Collider are presented. The data correspond to 36.1 fb−1of collisions collected by the ATLAS experiment in 2015 and 2016. Here ℓ and ℓ′ stand for electrons or muons. Integrated and differential ZZ→ℓ+ℓ−ℓ'+ℓ'− cross sections with Z→ℓ+ℓ− candidate masses in the range of 66 GeV to 116 GeV are measured in a fiducial phase space corresponding to the detector acceptance and corrected for detector effects. The differential cross sections are presented in bins of twenty observables, including several that describe the jet activity. The integrated cross section is also extrapolated to a total phase space and to all standard model decays of Z bosons with mass between 66 GeV and 116 GeV, resulting in a value of 17.3±0.9[±0.6(stat)±0.5(syst)±0.6(lumi)] pb. The measurements are found to be in good agreement with the standard model. A search for neutral triple gauge couplings is performed using the transverse momentum distribution of the leading Z boson candidate. No evidence for such couplings is found and exclusion limits are set on their parameters.

Measurement of the soft-drop jet mass in pp collisions at √s=13 TeV with the ATLAS detector

Thu 20 Jun 2019 09:42:47 KRAT

Jet substructure observables have significantly extended the search program for physics beyond the standard model at the Large Hadron Collider. The state-of-the-art tools have been motivated by theoretical calculations, but there has never been a direct comparison between data and calculations of jet substructure observables that are accurate beyond leading-logarithm approximation. Such observables are significant not only for probing the collinear regime of QCD that is largely unexplored at a hadron collider, but also for improving the understanding of jet substructure properties that are used in many studies at the Large Hadron Collider. This Letter documents a measurement of the first jet substructure quantity at a hadron collider to be calculated at next-to-next-to-leading-logarithm accuracy. The normalized, differential cross section is measured as a function of log10ρ2, where ρ is the ratio of the soft-drop mass to the ungroomed jet transverse momentum. This quantity is measured in dijet events from 32.9 fb−1 of √s=13 TeV proton-proton collisions recorded by the ATLAS detector. The data are unfolded to correct for detector effects and compared to precise QCD calculations and leading-logarithm particle-level Monte Carlo simulations.

Search for charged Higgs bosons decaying into top and bottom quarks at √s=13 TeV with the ATLAS detector

Thu 20 Jun 2019 09:42:41 KRAT

A search for charged Higgs bosons heavier than the top quark and decaying via H± → tb is presented. The data analysed corresponds to 36.1 fb−1 of pp collisions at s√=13 TeV and was recorded with the ATLAS detector at the LHC in 2015 and 2016. The production of a charged Higgs boson in association with a top quark and a bottom quark, pp → tbH±, is explored in the mass range from mH± = 200 to 2000 GeV using multi-jet final states with one or two electrons or muons. Events are categorised according to the multiplicity of jets and how likely these are to have originated from hadronisation of a bottom quark. Multivariate techniques are used to discriminate between signal and background events. No significant excess above the background-only hypothesis is observed and exclusion limits are derived for the production cross-section times branching ratio of a charged Higgs boson as a function of its mass, which range from 2.9 pb at mH± = 200 GeV to 0.070 pb at mH± = 2000 GeV. The results are interpreted in two benchmark scenarios of the Minimal Supersymmetric Standard Model.

Search for dark matter in events with a hadronically decaying vector boson and missing transverse momentum in pp collisions at √s = 13 TeV with the ATLAS detector

Thu 20 Jun 2019 09:42:36 KRAT

A search for dark matter (DM) particles produced in association with a hadronically decaying vector boson is performed using pp collision data at a centre-of-mass energy of s√=13 TeV corresponding to an integrated luminosity of 36.1 fb−1, recorded by the ATLAS detector at the Large Hadron Collider. This analysis improves on previous searches for processes with hadronic decays of W and Z bosons in association with large missing transverse momentum (mono-W/Z searches) due to the larger dataset and further optimization of the event selection and signal region definitions. In addition to the mono-W/Z search, the as yet unexplored hypothesis of a new vector boson Z′ produced in association with dark matter is considered (mono-Z′ search). No significant excess over the Standard Model prediction is observed. The results of the mono-W/Z search are interpreted in terms of limits on invisible Higgs boson decays into dark matter particles, constraints on the parameter space of the simplified vector-mediator model and generic upper limits on the visible cross sections for W/Z+DM production. The results of the mono-Z′ search are shown in the framework of several simplified-model scenarios involving DM production in association with the Z′ boson.

Measurement of dijet azimuthal decorrelations in pp collisions at √s=8 TeV with the ATLAS detector and determination of the strong coupling

Thu 20 Jun 2019 09:42:32 KRAT

A measurement of the rapidity and transverse momentum dependence of dijet azimuthal decorrelations is presented, using the quantity RΔϕ. The quantity RΔϕ specifies the fraction of the inclusive dijet events in which the azimuthal opening angle of the two jets with the highest transverse momenta is less than a given value of the parameter Δϕmax. The quantity RΔϕ is measured in proton-proton collisions at s=8 TeV as a function of the dijet rapidity interval, the event total scalar transverse momentum, and Δϕmax. The measurement uses an event sample corresponding to an integrated luminosity of 20.2 fb−1 collected with the ATLAS detector at the CERN Large Hadron Collider. Predictions of a perturbative QCD calculation at next-to-leading order in the strong coupling with corrections for nonperturbative effects are compared to the data. The theoretical predictions describe the data in the whole kinematic region. The data are used to determine the strong coupling αS and to study its running for momentum transfers from 260 GeV to above 1.6 TeV. Analysis that combines data at all momentum transfers results in αS(mZ)=0.1127−0.0027+0.0063.

Search for photonic signatures of gauge-mediated supersymmetry in 13 TeV pp collisions with the ATLAS detector

Thu 20 Jun 2019 09:42:32 KRAT

A search is presented for photonic signatures, motivated by generalized models of gauge-mediated supersymmetry breaking. This search makes use of proton-proton collision data at √s=13 TeVcorresponding to an integrated luminosity of 36.1 fb−1 recorded by the ATLAS detector at the LHC, and it explores models dominated by both strong and electroweak production of supersymmetric partner states. Experimental signatures incorporating an isolated photon and significant missing transverse momentum are explored. These signatures include events with an additional photon or additional jet activity not associated with any specific underlying quark flavor. No significant excess of events is observed above the Standard Model prediction, and 95% confidence-level upper limits of between 0.083 and 0.32 fb are set on the visible cross section of contributions from physics beyond the Standard Model. These results are interpreted in terms of lower limits on the masses of gluinos, squarks, and gauginos in the context of generalized models of gauge-mediated supersymmetry, which reach as high as 2.3 TeV for strongly produced and 1.3 TeV for weakly produced supersymmetric partner pairs.

Measurement of inclusive jet and dijet cross-sections in proton-proton collisions at √s=13 TeV with the ATLAS detector

Thu 20 Jun 2019 09:35:40 KRAT

Inclusive jet and dijet cross-sections are measured in proton-proton collisions at a centre-of-mass energy of 13 TeV. The measurement uses a dataset with an integrated luminosity of 3.2 fb−1 recorded in 2015 with the ATLAS detector at the Large Hadron Collider. Jets are identified using the anti-kt algorithm with a radius parameter value of R = 0.4. The inclusive jet cross-sections are measured double-differentially as a function of the jet transverse momentum, covering the range from 100 GeV to 3.5 TeV, and the absolute jet rapidity up to |y| = 3. The double-differential dijet production cross-sections are presented as a function of the dijet mass, covering the range from 300 GeV to 9 TeV, and the half absolute rapidity separation between the two leading jets within |y| < 3, y∗, up to y∗ = 3. Next-to-leading-order, and next-to-next-to-leading-order for the inclusive jet measurement, perturbative QCD calculations corrected for non-perturbative and electroweak effects are compared to the measured cross-sections.

Search for top-squark pair production in final states with one lepton, jets, and missing transverse momentum using 36 fb−1 of √s=13 TeV pp collision data with the ATLAS detector

Thu 20 Jun 2019 09:35:37 KRAT

The results of a search for the direct pair production of top squarks, the supersymmetric partner of the top quark, in final states with one isolated electron or muon, several energetic jets, and missing transverse momentum are reported. The analysis also targets spin-0 mediator models, where the mediator decays into a pair of dark-matter particles and is produced in association with a pair of top quarks. The search uses data from proton-proton collisions delivered by the Large Hadron Collider in 2015 and 2016 at a centre-of-mass energy of s√=13 TeV and recorded by the ATLAS detector, corresponding to an integrated luminosity of 36 fb−1. A wide range of signal scenarios with different mass-splittings between the top squark, the lightest neutralino and possible intermediate supersymmetric particles are considered, including cases where the W bosons or the top quarks produced in the decay chain are off-shell. No significant excess over the Standard Model prediction is observed. The null results are used to set exclusion limits at 95% confidence level in several supersymmetry benchmark models. For pair-produced top-squarks decaying into top quarks, top-squark masses up to 940 GeV are excluded. Stringent exclusion limits are also derived for all other considered top-squark decay scenarios. For the spin-0 mediator models, upper limits are set on the visible cross-section.

Search for charged Higgs bosons decaying via H± → τ±ντ in the τ+jets and τ+lepton final states with 36 fb−1 of pp collision data recorded at √s=13 TeV with the ATLAS experiment

Thu 20 Jun 2019 09:35:33 KRAT

Charged Higgs bosons produced either in top-quark decays or in association with a top-quark, subsequently decaying via H± → τ±ντ, are searched for in 36.1 fb−1 of proton-proton collision data at s√=13s=13 TeV recorded with the ATLAS detector. Depending on whether the top-quark produced together with H± decays hadronically or leptonically, the search targets τ+jets and τ+lepton final states, in both cases with a hadronically decaying τ-lepton. No evidence of a charged Higgs boson is found. For the mass range of mH±mH± = 90–2000 GeV, upper limits at the 95% confidence level are set on the production cross-section of the charged Higgs boson times the branching fraction B(H±→τ±ντ)B(H±→τ±ντ) in the range 4.2–0.0025 pb. In the mass range 90–160 GeV, assuming the Standard Model cross-section for tt¯tt¯ production, this corresponds to upper limits between 0.25% and 0.031% for the branching fraction B(t→bH±)×B(H±→τ±ντ)B(t→bH±)×B(H±→τ±ντ).

Система H2|GI|∞ с бесконечным значением среднего времени обслуживания

Thu 20 Aug 2020 11:37:30 KRAT

Проводится исследование математической модели системы массового обслуживания с неограниченным числом приборов и рекуррентным входящим потоком, в котором длины интервалов между моментами наступления событий имеют двухфазную гиперэкспоненциальную функцию распределения. С помощью метода динамического просеивания получены среднее значение и дисперсия числа заявок в системе. Предложена дискретная гауссовская аппроксимация нестационарного распределения вероятностей числа заявок в системе. С помощью имитационного моделирования установлена область применимости предлагаемой аппроксимации.

О вложении двуметрических феноменологически симметричных геометрий

Thu 14 Feb 2019 16:05:06 KRAT

Известна полная классификация двуметрических феноменологически симметричных геометрий двух множеств ранга (n+1, 2), где n = 1, 2,… . Функции, задающие эти геометрии, локально изотопны почти n-транзитивным действиям некоторых групп на двумерном многообразии. Доказывается, что функция, задающая двуметрическую ФС ГДМ ранга (n+2, 2), содержит как аргумент функцию, задающую некоторую двуметрическую ФС ГДМ ранга (n+1, 2). Доказательство сводится к исследованию групп преобразований. В конце доказывается, что все рассматриваемые здесь группы преобразований являются почти n-транзитивными.

Localized plasmon resonance in boron-doped multiwalled carbon nanotubes

Thu 13 Jun 2019 10:07:22 KRAT

Substitutionally boron-doped multiwalled carbon nanotubes (B-CNTs) with lengths mainly less than 0.5 μ m and diameters 10–30 nm have been obtained by arc-discharge evaporation of the graphite anode containing boron material. The broad peak has been observed in the midinfrared conductivity spectra of the thin film comprising B-CNTs. The peak was suggested to be associated with a phenomenon known as localized plasmon resonance. Theoretical analysis has been done to confirm the possibility of this phenomenon to occur in the B-CNTs.

Specifics of geological composition, geochemistry and geochronology of rocks from the Kresty alkaline-ultrabasic massif (Maimecha-Kotui province, Polar Siberia)

Thu 10 Jan 2019 11:05:32 KRAT

In this work, we demonstrate new data that allows us to accurate geochronological ranges of formation of the Kresty alkaline-ultrabasic massif, which is considered to be a satellite of the Gulinian giant pluton. We also interpreted geological, geochemical and isotope-geochemical data obtained earlier for major varieties of this volcanic-plutonic association taking into account new geochronological results, as well as considered new aspects/information on matter source of alkaline-ultrabasic massifs from this province. One of the main aspects is interaction of Siberian super plume matter with hosting substrate of Siberian craton continental crust.

Закономерности организации растительности песчаных степей долин рек Самары, Урала и их притоков (Оренбургская область)

Thu 10 Jan 2019 10:58:41 KRAT

На основании анализа 122 геоботанических описаний песчаных степей Оренбургской области определены закономерности организации псаммофитной растительности. Проведен кластерный анализ с использованием различных индексов подобия. Показано, что лучшие результаты в дифференциации кластеров дает использование коэффициента Сокала - Снита. Выделено и охарактеризовано пять типов сообществ. CCA-ординация позволила оценить роль антропогенной трансформации и географических различий в дифференциации псаммофитной растительности.

О решении квазистатических задач микро- и мезомеханики в динамической постановке

Thu 10 Jan 2019 10:58:38 KRAT

При моделировании характерных процессов на мезоуровне расчетная область содержит большое количество структурных элементов (зерен, включений, пор и т.д.), которые необходимо аппроксимировать расчетной сеткой с достаточной степенью подробности. Известно, что требования к вычислительным мощностям нелинейно возрастают с увеличением количества расчетных элементов. В связи с этим актуальной проблемой при решении задач микромеханики является минимизация вычислительных затрат без потери информативности и точности решения. Существенно минимизировать вычислительные затраты позволяет решение задач квазистатики в динамической постановке. В настоящей работе исследованы условия применимости динамических подходов для моделирования процессов квазистатического деформирования в задачах микро- и мезомеханики, где микроструктура рассматривается в явном виде. Конечно-элементные расчеты квазистатического растяжения в динамической и статической постановках задачи проводились для модельных материалов, нечувствительных к скорости деформации. Показано, что основным параметром, влияющим на совпадение решения динамической задачи со статическим решением, является время, за которое скорость деформирования достигает амплитудного значения. При условии линейного возрастания скорости в течение времени, за которое упругая волна проходит через образец более двух раз, погрешность отклонения динамического решения от статического не превышает 0.1 %. При этом требуемая оперативная память и время вычислений статической задачи превышают на порядок аналогичные затраты на расчеты в динамической постановке. Таким образом, на примере модельных структур показана возможность и целесообразность использования явных динамических методов для решения квазистатических задач микро- и мезомеханики.

Search for Higgs bosons produced via vector-boson fusion and decaying into bottom quark pairs in √s=13 TeV pp collisions with the ATLAS detector

Thu 07 Nov 2019 09:25:20 KRAT

A search for the bb¯ decay of the Standard Model Higgs boson produced through vector-boson fusion is presented. Three mutually exclusive channels are considered: two all-hadronic channels and a photon-associated channel. Results are reported from the analysis of up to 30.6 fb−1 of pp data at s=13 TeV collected with the ATLAS detector at the LHC. The measured signal strength relative to the Standard Model prediction from the combined analysis is 2.5−1.3+1.4 for inclusive Higgs boson production and 3.0−1.6+1.7 for vector-boson fusion production only.

Search for low-mass dijet resonances using trigger-level jets with the Atlas detector in pp collisions at √s=13 TeV

Thu 06 Jun 2019 18:34:51 KRAT

Searches for dijet resonances with sub-TeV masses using the ATLAS detector at the Large Hadron Collider can be statistically limited by the bandwidth available to inclusive single-jet triggers, whose data-collection rates at low transverse momentum are much lower than the rate from standard model multijet production. This Letter describes a new search for dijet resonances where this limitation is overcome by recording only the event information calculated by the jet trigger algorithms, thereby allowing much higher event rates with reduced storage needs. The search targets low-mass dijet resonances in the range 450–1800 GeV. The analyzed data set has an integrated luminosity of up to 29.3 fb−1 and was recorded at a center-of-mass energy of 13 TeV. No excesses are found; limits are set on Gaussian-shaped contributions to the dijet mass distribution from new particles and on a model of dark-matter particles with axial-vector couplings to quarks.

Search for flavor-changing neutral currents in top quark decays t→Hc and t→Hu in multilepton final states in proton-proton collisions at √s=13 TeV with the ATLAS detector

Thu 06 Jun 2019 18:34:47 KRAT

Flavor-changing neutral currents are not present in the Standard Model at tree level and are suppressed in loop processes by the unitarity of the Cabibbo-Kobayashi-Maskawa matrix; the corresponding rates for top quark decay processes are experimentally unobservable. Extensions of the Standard Model can generate new flavor-changing neutral current processes, leading to signals which, if observed, would be unambiguous evidence of new interactions. A data set corresponding to an integrated luminosity of 36.1 fb-1 of pp collisions at a center-of-mass energy of s=13 TeV recorded with the ATLAS detector at the Large Hadron Collider is used to search for top quarks decaying to up or charm quarks with the emission of a Higgs boson, with subsequent Higgs boson decay to final states with at least one electron or muon. No signal is observed and limits on the branching fractions B(t→Hc)<0.16% and B(t→Hu)<0.19% at 95% confidence level are obtained (with expected limits of 0.15% in both cases).

Search for resonances in the mass distribution of jet pairs with one or two jets identified as b-jets in proton-proton collisions at √s=13 TeV with the ATLAS detector

Thu 06 Jun 2019 18:27:48 KRAT

A search for new resonances decaying into jets containing b-hadrons in pp collisions with the ATLAS detector at the LHC is presented in the dijet mass range from 0.57 to 7 TeV. The data set corresponds to an integrated luminosity of up to 36.1 fb−1 collected in 2015 and 2016 at s=13 TeV. No evidence of a significant excess of events above the smooth background shape is found. Upper cross-section limits and lower limits on the corresponding signal mass parameters for several types of signal hypotheses are provided at 95% C.L. In addition, 95% C.L. upper limits are set on the cross sections for new processes that would produce Gaussian-shaped signals in the di-b-jet mass distributions.

Исследование группы автоморфизмов кода, ассоциированного с оптимальной кривой рода три

Thu 04 Oct 2018 09:52:08 KRAT

Установлены условия, при которых группа автоморфизмов оптимальной кривой рода три над конечным полем с дискриминантом из множества {-19, -43, -67,-163} изоморфна группе автоморфизмов АГ-кода, асоциированного с такой кривой.

On the wave zone of synchrotron radiation

Mon 30 Nov 2020 10:07:19 KRAT

The extension of the wave zone of synchrotron radiation is studied.

Third order extensions of 3d Chern-Simons interacting to gravity: Hamiltonian formalism and stability

Mon 23 Nov 2020 12:41:14 KRAT

We consider inclusion of interactions between 3d Einstein gravity and the third order extensions of Chern–Simons. Once the gravity is minimally included into the third order vector field equations, the theory is shown to admit a two-parameter series of symmetric tensors with on-shell vanishing covariant divergence. The canonical energy–momentum is included into the series. For a certain range of the model parameters, the series include the tensors that meet the weak energy condition, while the canonical energy is unbounded in all the instances. Because of the on-shell vanishing covariant divergence, any of these tensors can be considered as an appropriate candidate for the right hand side of Einstein's equations. If the source differs from the canonical energy momentum, the coupling is non-Lagrangian while the interaction remains consistent with any of the tensors. We reformulate these not necessarily Lagrangian third order equations in the first order formalism which is covariant in the sense of 1+2 decomposition. After that, we find the Poisson bracket such that the first order equations are Hamiltonian in all the instances, be the original third order equations Lagrangian or not. The brackets differ from canonical ones in the matter sector, while the gravity admits the usual PB's in terms of ADM variables. The Hamiltonian constraints generate lapse, shift and gauge transformations of the vector field with respect to these Poisson brackets. The Hamiltonian constraint, being the lapse generator, is interpreted as strongly conserved energy. The matter contribution to the Hamiltonian constraint corresponds to 00-component of the tensor included as a source in the right hand side of Einstein equations. Once the 00-component of the tensor is bounded, the theory meets the usual sufficient condition of classical stability, while the original field equations are of the third order.

Процессы интерференции при переизлучении графеном аттосекундных импульсов электромагнитного поля

Mon 21 Feb 2022 10:01:17 KRAT

Рассмотрены интерференционные спектры при переизлучении аттосекундных импульсов электромагнитного поля листами графена. Получены аналитические выражения для расчетов спектральных распределений. В качестве примера проведено сравнение интерференционных спектров графенового листа и плоской прямоугольной решетки.

К парастатистике в квантовой неэкстенсивной статистической механике

Mon 21 Feb 2022 09:19:25 KRAT

На основе квантовых состояний Бозе в парастатистике определены уравнения для равновесного распределения квантовых аддитивных и неэкстенсивных систем. Находятся флуктуации и дисперсии физических величин для равновесной системы. Определяется абелева группа микроскопических энтропий для закона композиции с квадратичной нелинейностью.

Инфляционный режим эволюции масштабного фактора в релятивистской теории гравитации с массой гравитона

Mon 21 Feb 2022 09:19:19 KRAT

Показано, что космологическая среда, состоящая из кинетической и потенциальной компонент, в начале эволюции является вакуумно-подобной, а в конце эволюции она асимптотически становится квинтэссенцией.

Spin-flavor oscillations of Dirac neutrinos in a plane electromagnetic wave

Mon 11 Jan 2021 11:34:33 KRAT

We study spin and spin-flavor oscillations of Dirac neutrinos in a plane electromagnetic wave with circular polarization. The evolution of massive neutrinos with nonzero magnetic moments in the field of an electromagnetic wave is based on the exact solution of the Dirac-Pauli equation. We formulate the initial condition problem to describe spin-flavor oscillations in an electromagnetic wave. The transition probabilities for spin and spin-flavor oscillations are obtained. In case of spin-flavor oscillations, we analyze the transition and survival probabilities for different neutrino magnetic moments and various channels of neutrino oscillations. As an application of the obtained results, we study the possibility of existence of νeL→νμR oscillations in an electromagnetic wave emitted by a highly magnetized neutron star. Our results are compared with findings of other authors.

Measurement of differential cross sections and W+/W− cross-section ratios for W boson production in association with jets at √s=8 TeV with the ATLAS detector

Mon 10 Jun 2019 16:47:56 KRAT

This paper presents a measurement of the W boson production cross section and the W +/W − cross-section ratio, both in association with jets, in proton-proton collisions at sqrt{s}=8 TeV with the ATLAS experiment at the Large Hadron Collider. The measurement is performed in final states containing one electron and missing transverse momentum using data corresponding to an integrated luminosity of 20.2 fb−1. Differential cross sections for events with at least one or two jets are presented for a range of observables, including jet transverse momenta and rapidities, the scalar sum of transverse momenta of the visible particles and the missing transverse momentum in the event, and the transverse momentum of the W boson. For a subset of the observables, the differential cross sections of positively and negatively charged W bosons are measured separately. In the cross-section ratio of W +/W − the dominant systematic uncertainties cancel out, improving the measurement precision by up to a factor of nine. The observables and ratios selected for this paper provide valuable input for the up quark, down quark, and gluon parton distribution functions of the proton.

Search for supersymmetry in final states with missing transverse momentum and multiple b-jets in proton-proton collisions at √s=13 TeV with the ATLAS detector

Mon 10 Jun 2019 16:33:28 KRAT

A search for supersymmetry involving the pair production of gluinos decaying via third-generation squarks into the lightest neutralino (χ~01) is reported. It uses LHC proton-proton collision data at a centre-of-mass energy s√=13 TeV with an integrated luminosity of 36.1 fb−1 collected with the ATLAS detector in 2015 and 2016. The search is performed in events containing large missing transverse momentum and several energetic jets, at least three of which must be identified as originating from b-quarks. To increase the sensitivity, the sample is divided into subsamples based on the presence or absence of electrons or muons. No excess is found above the predicted background. For χ~01 masses below approximately 300 GeV, gluino masses of less than 1.97 (1.92) TeV are excluded at 95% confidence level in simplified models involving the pair production of gluinos that decay via top (bottom) squarks. An interpretation of the limits in terms of the branching ratios of the gluinos into third-generation squarks is also provided. These results improve upon the exclusion limits obtained with the 3.2 fb−1 of data collected in 2015.

Search for Higgs boson decays to beyond-the-Standard-Model light bosons in four-lepton events with the ATLAS detector at √s=13 TeV

Mon 10 Jun 2019 16:33:26 KRAT

A search is conducted for a beyond-the-Standard-Model boson using events where a Higgs boson with mass 125 GeV decays to four leptons (ℓ = e or μ). This decay is presumed to occur via an intermediate state which contains one or two on-shell, promptly decaying bosons: H → ZX/XX → 4ℓ, where X is a new vector boson Zd or pseudoscalar a with mass between 1 and 60 GeV. The search uses pp collision data collected with the ATLAS detector at the LHC with an integrated luminosity of 36.1 fb−1 at a centre-of-mass energy s√=13 TeV. No significant excess of events above Standard Model background predictions is observed; therefore, upper limits at 95% confidence level are set on modelindependent fiducial cross-sections, and on the Higgs boson decay branching ratios to vector and pseudoscalar bosons in two benchmark models.

Search for flavour-changing neutral current top-quark decays t → qZ in proton-proton collisions at √s=13 TeV with the ATLAS detector

Mon 10 Jun 2019 16:33:20 KRAT

A search for flavour-changing neutral-current processes in top-quark decays is presented. Data collected with the ATLAS detector from proton-proton collisions at the Large Hadron Collider at a centre-of-mass energy of s√=13 TeV, corresponding to an integrated luminosity of 36.1 fb−1, are analysed. The search is performed using top-quark pair events, with one top quark decaying through the t → qZ (q = u, c) flavour-changing neutral-current channel, and the other through the dominant Standard Model mode t → bW. Only Z boson decays into charged leptons and leptonic W boson decays are considered as signal. Consequently, the final-state topology is characterized by the presence of three isolated charged leptons (electrons or muons), at least two jets, one of the jets originating from a b-quark, and missing transverse momentum from the undetected neutrino. The data are consistent with Standard Model background contributions, and at 95% confidence level the search sets observed (expected) upper limits of 1.7 × 10−4 (2.4 × 10−4) on the t → uZ branching ratio and 2.4 × 10−4 (3.2 × 10−4) on the t → cZ branching ratio, constituting the most stringent limits to date.

Search for long-lived charginos based on a disappearing-track signature in pp collisions at √s=13 TeV with the ATLAS detector

Mon 10 Jun 2019 16:33:16 KRAT

This paper presents a search for direct electroweak gaugino or gluino pair production with a chargino nearly mass-degenerate with a stable neutralino. It is based on an integrated luminosity of 36.1 fb−1 of pp collisions at s√=13 TeV collected by the ATLAS experiment at the LHC. The final state of interest is a disappearing track accompanied by at least one jet with high transverse momentum from initial-state radiation or by four jets from the gluino decay chain. The use of short track segments reconstructed from the innermost tracking layers significantly improves the sensitivity to short chargino lifetimes. The results are found to be consistent with Standard Model predictions. Exclusion limits are set at 95% confidence level on the mass of charginos and gluinos for different chargino lifetimes. For a pure wino with a lifetime of about 0.2 ns, chargino masses up to 460 GeV are excluded. For the strong production channel, gluino masses up to 1.65 TeV are excluded assuming a chargino mass of 460 GeV and lifetime of 0.2 ns.

Features of geology and composition of rocks from the alkaline-gabbroic University massif (N-E Kuznetsky Alatau ridge, Siberia)

Mon 07 Sep 2020 11:00:19 KRAT

This paper discusses specifics of petrography and structural tectonic position of the alkaline-gabbroic University massif, which is a sort of analogue of the Kiya-Shaltyr deposit of nepheline ores in this area that was very slightly eroded. In this work, we will also present new precise analytical data on rare and trace element distribution in major intrusive phases of this geological object, and also isotope dating on the basis of method Sm-Nd.

Асимптотика решения задачи Коши при нарушении устойчивости точки покоя в плоскости "быстрых движений"

Mon 01 Oct 2018 13:19:06 KRAT

Получена асимптотическая оценка для решения сингулярно возмущенной задачи Коши при нарушении устойчивости точки покоя в плоскости «быстрых движений». Построен главный член асимптотического разложения решения, который имеет отрицательную дробную степень по малому параметру, что свойственно бисингулярно возмущенным уравнениям или уравнениям с точками поворота.

Ассоциированные левоинвариантные контактные метрические структуры на семимерной группе Гейзенберга H7

Mon 01 Oct 2018 13:18:31 KRAT

Построены новые ассоциированные левоинвариантные контактные метрические структуры на семимерной группе Гейзенберга H7. Изучен общий двенадцатипараметрический класс таких структур, подробно рассмотрены четыре подкласса. Основной результат работы сформулирован в виде

Constraints on off-shell Higgs boson production and the Higgs boson total width in ZZ→4ℓ and ZZ→2ℓ2ν final states with the ATLAS detector

Fri 24 May 2019 17:54:28 KRAT

A measurement of off-shell Higgs boson production in the and decay channels, where ℓ stands for either an electron or a muon, is performed using data from proton–proton collisions at a centre-of-mass energy of TeV. The data were collected by the ATLAS experiment in 2015 and 2016 at the Large Hadron Collider, and they correspond to an integrated luminosity of . An observed (expected) upper limit on the off-shell Higgs signal strength, defined as the event yield normalised to the Standard Model prediction, of 3.8 (3.4) is obtained at 95% confidence level (CL). Assuming the ratio of the Higgs boson couplings to the Standard Model predictions is independent of the momentum transfer of the Higgs production mechanism considered in the analysis, a combination with the on-shell signal-strength measurements yields an observed (expected) 95% CL upper limit on the Higgs boson total width of 14.4 (15.2) MeV.

Search for pair production of Higgsinos in final states with at least three b-tagged jets in √s=13 TeV pp collisions using the ATLAS detector

Fri 24 May 2019 17:47:25 KRAT

A search for pair production of the supersymmetric partners of the Higgs boson (higgsinos H˜) in gauge-mediated scenarios is reported. Each higgsino is assumed to decay to a Higgs boson and a gravitino. Two complementary analyses, targeting high- and low-mass signals, are performed to maximize sensitivity. The two analyses utilize LHC pp collision data at a center-of-mass energy s=13 TeV, the former with an integrated luminosity of 36.1 fb-1 and the latter with 24.3 fb-1, collected with the ATLAS detector in 2015 and 2016. The search is performed in events containing missing transverse momentum and several energetic jets, at least three of which must be identified as b-quark jets. No significant excess is found above the predicted background. Limits on the cross section are set as a function of the mass of the H˜ in simplified models assuming production via mass-degenerate higgsinos decaying to a Higgs boson and a gravitino. Higgsinos with masses between 130 and 230 GeV and between 290 and 880 GeV are excluded at the 95% confidence level. Interpretations of the limits in terms of the branching ratio of the higgsino to a Z boson or a Higgs boson are also presented, and a 45% branching ratio to a Higgs boson is excluded for mH˜≈400 GeV.

Measurements of b-jet tagging efficiency with the ATLAS detector using tt¯ events at √s=13 TeV

Fri 23 Aug 2019 11:14:18 KRAT

The efficiency to identify jets containing b-hadrons (b-jets) is measured using a high purity sample of dileptonic top quark-antiquark pairs ( tt¯ ) selected from the 36.1 fb−1 of data collected by the ATLAS detector in 2015 and 2016 from proton-proton collisions produced by the Large Hadron Collider at a centre-of-mass energy s√=13 TeV. Two methods are used to extract the efficiency from tt¯ events, a combinatorial likelihood approach and a tag-and-probe method. A boosted decision tree, not using b-tagging information, is used to select events in which two b-jets are present, which reduces the dominant uncertainty in the modelling of the flavour of the jets. The efficiency is extracted for jets in a transverse momentum range from 20 to 300 GeV, with data-to-simulation scale factors calculated by comparing the efficiency measured using collision data to that predicted by the simulation. The two methods give compatible results, and achieve a similar level of precision, measuring data-to-simulation scale factors close to unity with uncertainties ranging from 2% to 12% depending on the jet transverse momentum.

Search for pair production of heavy vector-like quarks decaying into high-pT W bosons and top quarks in the lepton-plus-jets final state in pp collisions at √s=13 TeV with the ATLAS detector

Fri 23 Aug 2019 11:14:17 KRAT

A search is presented for the pair production of heavy vector-like B quarks, primarily targeting B quark decays into a W boson and a top quark. The search is based on 36.1 fb−1 of pp collisions at s√=13 TeV recorded in 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. Data are analysed in the lepton-plus-jets final state, characterised by a high-transverse-momentum isolated electron or muon, large missing transverse momentum, and multiple jets, of which at least one is b-tagged. No significant deviation from the Standard Model expectation is observed. The 95% confidence level lower limit on the B mass is 1350 GeV assuming a 100% branching ratio to Wt. In the SU(2) singlet scenario, the lower mass limit is 1170 GeV. The 100% branching ratio limits are found to be also applicable to heavy vector-like X production, with charge +5/3, that decay into Wt. This search is also sensitive to a heavy vector-like B quark decaying into other final states (Zb and Hb) and thus mass limits on B production are set as a function of the decay branching ratios.

Multi-Hamiltonian formulations and stability of higher-derivative extensions of 3d Chern-Simons

Fri 20 Jan 2023 12:44:29 KRAT

Most general third-order 3d linear gauge vector field theory is considered. The field equations involve, besides the mass, two dimensionless constant parameters. The theory admits two-parameter series of conserved tensors with the canonical energy-momentum being a particular representative of the series. For a certain range of the model parameters, the series of conserved tensors include bounded quantities. This makes the dynamics classically stable, though the canonical energy is unbounded in all the instances. The free third-order equations are shown to admit constrained multi-Hamiltonian form with the 00-components of conserved tensors playing the roles of corresponding Hamiltonians. The series of Hamiltonians includes the canonical Ostrogradski’s one, which is unbounded. The Hamiltonian formulations with different Hamiltonians are not connected by canonical transformations. This means, the theory admits inequivalent quantizations at the free level. Covariant interactions are included with spinor fields such that the higher-derivative dynamics remains stable at interacting level if the bounded conserved quantity exists in the free theory. In the first-order formalism, the interacting theory remains Hamiltonian and therefore it admits quantization, though the vertices are not necessarily Lagrangian in the third-order field equations.

Морфологический и молекулярно-генетический подходы к изучению рода Dactylorhiza в Республике Коми

Fri 19 Oct 2018 16:09:55 KRAT

Представлены результаты изучения видов рода Dactylorhiza Neck. ex Nevski на территории Республики Коми. На основании анализа маркерных последовательностей ДНК (ITS1-5.8S-ITS2) и 19 морфометрических признаков 480 растений изучено 16 ценопопуляций видов рода в регионе. Совместное использование морфологического и молекулярно-генетического подходов позволило подтвердить произрастание на территории Республики Коми 4 видов: Dactylorhiza fuchsii (Druce) Soό, D. maculata (L.) Soό, D. incarnata (L.) Soό s. l. (включая D. cruenta (O. F. Muell) Soó) и D. traunsteineri (Saut.) Soó. D. cruentа, по-видимому, стоит рассматривать как подвид (или разновидность) D. incarnata. Приведены морфологические признаки, позволяющие разделить виды внутри рода, ими стали ширина губы и шпорца, длина прицветника, ширина нижних листьев. Получены новые молекулярно-филогенетические данные для этих видов. Вопрос о наличии D. baltica (Klinge) Orlova на территории региона остается открытым и требует дополнительных исследований.

Measurement of differential cross sections of isolated-photon plus heavy-flavour jet production in pp collisions at √s=8 TeV using the ATLAS detector

Fri 19 Oct 2018 15:39:47 KRAT

This Letter presents the measurement of differential cross sections of isolated prompt photons produced in association with a b-jet or a c-jet. These final states provide sensitivity to the heavy-flavour content of the proton and aspects related to the modelling of heavy-flavour quarks in perturbative QCD. The measurement uses proton–proton collision data at a centre-of-mass energy of 8 TeV recorded by the ATLAS detector at the LHC in 2012 corresponding to an integrated luminosity of up to 20.2 fb−1. The differential cross sections are measured for each jet flavour with respect to the transverse energy of the leading photon in two photon pseudorapidity regions: and . The measurement covers photon transverse energies GeV and GeV respectively for the two regions. For each jet flavour, the ratio of the cross sections in the two regions is also measured. The measurement is corrected for detector effects and compared to leading-order and next-to-leading-order perturbative QCD calculations, based on various treatments and assumptions about the heavy-flavour content of the proton. Overall, the predictions agree well with the measurement, but some deviations are observed at high photon transverse energies. The total uncertainty in the measurement ranges between 13% and 66%, while the central measurement exhibits the smallest uncertainty, ranging from 13% to 27%, which is comparable to the precision of the theoretical predictions.

Probability of radiation of twisted photons by classical currents

Fri 18 Dec 2020 10:49:06 KRAT

isted photon produced by a classical current is equal to the average number of twisted photons in a given state. The general formula for the projection of the total angular momentum of twisted photons with given the energy, the longitudinal projection of momentum, and the helicity is obtained. The symmetry property of the average number of twisted photons produced by a charged particle moving along a planar trajectory is found. The explicit formulas for the average number of twisted photons generated by undulators both in the dipole and wiggler regimes are obtained. It is established that, for the forward radiation of an ideal right-handed helical undulator, the harmonic number n of the twisted photon coincides with its projection of the total angular momentum m. As for the ideal left-handed helicalThe general formula for the probability of radiation of a twisted photon by a classical current is derived. The general theory of generation of twisted photons by undulators is developed. It is proved that the probability to record a tw undulator, we obtain that m=−n. It is found that the forward radiation of twisted photons by a planar undulator obeys the selection rule that n+m is an even number. It turns out that the average number of twisted photons produced by the undulator and detected off the undulator axis is a periodic function of m in a certain spectral band of the quantum numbers m.

Абелевы группы с достаточно π-регулярным кольцом эндоморфизмов

Fri 16 Oct 2020 15:43:12 KRAT

Понятие π-регулярного кольца эндоморфизмов абелевой группы, обобщающее понятие регулярного кольца эндоморфизмов, было введено в работах Л. Фукса и К. Рангасвами. Они описали периодические абелевы группы, имеющие π-регулярные кольца эндоморфизмов. Нашли некоторые необходимые условия для абелевой группы иметь π-регулярное кольцо эндоморфизмов. В данной статье исследуются абелевы группы с достаточно π-регулярным кольцом эндоморфизмов — подкласс абелевых групп, обладающих π-регулярным кольцом эндоморфизмов. Найдены некоторые необходимые и достаточные условия для произвольных абелевых групп иметь достаточно π-регулярное кольцо эндоморфизмов.

Bootstrapping non-commutative gauge theories from L∞ algebras

Fri 16 Oct 2020 15:21:56 KRAT

Non-commutative gauge theories with a non-constant NC-parameter are investigated. As a novel approach, we propose that such theories should admit an underlying L$_infty$ algebra, that governs not only the action of the symmetries but also the dynamics of the theory. Our approach is well motivated from string theory. We recall that such field theories arise in the context of branes in WZW models and briefly comment on its appearance for integrable deformations of AdS$_5$ sigma models. For the SU(2) WZW model, we show that the earlier proposed matrix valued gauge theory on the fuzzy 2-sphere can be bootstrapped via an L$_infty$ algebra. We then apply this approach to the construction of non-commutative Chern-Simons and Yang-Mills theories on flat and curved backgrounds with non-constant NC-structure. More concretely, up to the second order, we demonstrate how derivative and curvature corrections to the equations of motion can be bootstrapped in an algebraic way from the L$_infty$ algebra. The appearance of a non-trivial A$_infty$ algebra is discussed, as well.

Amplification of spontaneous emission on sodium D-lines using nonresonance broadband optical pumping

Fri 15 Jun 2018 11:50:25 KRAT

We describe experiments on the excitation of amplified spontaneous emission on the D-lines of sodium (D2 = 588.9 nm; D1 = 589.6 nm) with longitudinal optical pumping with a large detuning from the D2 line toward shorter wavelengths. The radiation spectra are measured, showing gain on both lines, at a Na concentration of (1–5) × 1014 cm–3, buffer gas (helium) pressure of 600 Torr at the working temperature, and pumping power density of more than 1.5 MW/cm2. The time characteristics show that the output radiation varies versus the concentration of sodium atoms in the active medium. The dependences of radiation absorption at the D-lines of sodium on the concentration of Na atoms and buffer gas pressure are given.

Нижняя оценка мощности наибольшего метрически регулярного подмножества булева куба

Fri 14 Sep 2018 13:53:37 KRAT

Исследуются строго метрические регулярные подмножества булева куба. Представлены итеративные конструкции таких множеств. Получена формула для вычисления количества строго метрически регулярных множеств, получаемых с помощью данных конструкций. Построены специальные семейства метрически регулярных множеств и вычислены мощности множеств из этих семейств. Полученные значения дают нижнюю оценку мощности наибольших метрически регулярных множеств при фиксированном радиусе покрытия.

Search for resonant and nonresonant Higgs boson pair production in the b¯ bτ + τ − decay channel in pp collisions at √s = 13 TeV with the ATLAS detector

Fri 14 Jun 2019 09:51:33 KRAT

A search for resonant and nonresonant pair production of Higgs bosons in the b¯bτ+τ− final state is presented. The search uses 36.1 fb−1 of pp collision data with √s=13 TeV recorded by the ATLAS experiment at the LHC in 2015 and 2016. Decays of the τ-lepton pairs with at least one τ lepton decaying to final states with hadrons and a neutrino are considered. No significant excess above the expected background is observed in the data. The cross-section times branching ratio for nonresonant Higgs boson pair production is constrained to be less than 30.9 fb, 12.7 times the standard model expectation, at 95% confidence level. The data are also analyzed to probe resonant Higgs boson pair production, constraining a model with an extended Higgs sector based on two doublets and a Randall-Sundrum bulk graviton model. Upper limits are placed on the resonant Higgs boson pair production cross-section times branching ratio, excluding resonances X in the mass range 305 GeV

Observation of H → b ¯b decays and VH production with the ATLAS detector

Fri 14 Jun 2019 09:44:40 KRAT

A search for the decay of the Standard Model Higgs boson into a pair when produced in association with a W or Z boson is performed with the ATLAS detector. The data, corresponding to an integrated luminosity of were collected in proton–proton collisions during Run 2 of the Large Hadron Collider at a centre-of-mass energy of . For a Higgs boson mass of , an excess of events over the expected background from other Standard Model processes is found with an observed (expected) significance of 4.9 (4.3) standard deviations. A combination with the results from other searches in Run 1 and in Run 2 for the Higgs boson in the decay mode is performed, which yields an observed (expected) significance of 5.4 (5.5) standard deviations, thus providing direct observation of the Higgs boson decay into b-quarks. The ratio of the measured event yield for a Higgs boson decaying into to the Standard Model expectation is . Additionally, a combination of Run 2 results searching for the Higgs boson produced in association with a vector boson yields an observed (expected) significance of 5.3 (4.8) standard deviations.

Spectral estimates of the p-Laplace Neumann operator and Brennan's conjecture

Fri 14 Jun 2019 09:44:38 KRAT

In this paper we obtain lower estimates for the first non-trivial eigenvalue of the p-Laplace Neumann operator in bounded simply connected planar domains Ω⊂R2 . This study is based on a quasiconformal version of the universal two-weight Poincaré–Sobolev inequalities obtained in our previous papers for conformal weights and its non weighted version for so-called K-quasiconformal α -regular domains. The main technical tool is the geometric theory of composition operators in relation with the Brennan’s conjecture for (quasi)conformal mappings.

Measurement of the suppression and azimuthal anisotropy of muons from heavy-flavor decays in Pb+Pb collisions at √sNN = 2.76 TeV with the ATLAS detector

Fri 14 Jun 2019 09:44:37 KRAT

ATLAS measurements of the production of muons from heavy-flavor decays in √sNN=2.76 TeV Pb+Pb collisions and √s=2.76 TeV pp collisions at the LHC are presented. Integrated luminosities of 0.14 nb−1 and 570 nb−1 are used for the Pb+Pb and pp measurements, respectively, which are performed over the muon transverse momentum range 4

Prompt and non-prompt J/ψ elliptic flow in Pb+Pb collisions at √sNN=5.02 Tev with the ATLAS detector

Fri 14 Jun 2019 09:44:36 KRAT

The elliptic flow of prompt and non-prompt J/ψJ/ψ was measured in the dimuon decay channel in Pb+Pb collisions at sNN−−−√=5.02sNN=5.02 TeVTeV with an integrated luminosity of 0.42 nb−10.42 nb−1 with the ATLAS detector at the LHC. The prompt and non-prompt signals are separated using a two-dimensional simultaneous fit of the invariant mass and pseudo-proper decay time of the dimuon system from the J/ψJ/ψ decay. The measurement is performed in the kinematic range of dimuon transverse momentum and rapidity 9

Amplitude analysis of the KSKS system produced in radiative J/ψ decays

Fri 14 Jun 2019 09:44:34 KRAT

An amplitude analysis of the KSKS system produced in radiative J/ψ decays is performed using the (1310.6±7.0)×106 J/ψ decays collected by the BESIII detector. Two approaches are presented. A mass-dependent analysis is performed by parametrizing the KSKS invariant mass spectrum as a sum of Breit-Wigner line shapes. Additionally, a mass-independent analysis is performed to extract a piecewise function that describes the dynamics of the KSKS system while making minimal assumptions about the properties and number of poles in the amplitude. The dominant amplitudes in the mass-dependent analysis include the f0(1710), f0(2200), and f′2(1525). The mass-independent results, which are made available as input for further studies, are consistent with those of the mass-dependent analysis and are useful for a systematic study of hadronic interactions. The branching fraction of radiative J/ψ decays to KSKS is measured to be (8.1±0.4)×10−4, where the uncertainty is systematic and the statistical uncertainty is negligible.

Combination of searches for heavy resonances decaying into bosonic and leptonic final states using 36 fb−1 of proton-proton collision data at √s=13 TeV with the ATLAS detector

Fri 14 Jun 2019 09:37:39 KRAT

Searches for new heavy resonances decaying into different pairings of W, Z, or Higgs bosons, as well as directly into leptons, are presented using a data sample corresponding to 36.1 fb−1 of pp collisions at √s=13 TeV collected during 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. Analyses selecting bosonic decay modes in the qqqq, ννqq, ℓνqq, ℓℓqq, ℓνℓν, ℓℓνν, ℓνℓℓ, ℓℓℓℓ, qqbb, ννbb, ℓνbb, and ℓℓbb final states are combined, searching for a narrow-width resonance. Likewise, analyses selecting the leptonic ℓν and ℓℓ final states are also combined. These two sets of analyses are then further combined. No significant deviation from the Standard Model predictions is observed. Three benchmark models are tested: a model predicting the existence of a new heavy scalar singlet, a simplified model predicting a heavy vector-boson triplet, and a bulk Randall-Sundrum model with a heavy spin-2 Kaluza-Klein excitation of the graviton. Cross section limits are set at the 95% confidence level using an asymptotic approximation and are compared with predictions for the benchmark models. These limits are also expressed in terms of constraints on couplings of the heavy vector-boson triplet to quarks, leptons, and the Higgs boson. The data exclude a heavy vector-boson triplet with mass below 5.5 TeV in a weakly coupled scenario and 4.5 TeV in a strongly coupled scenario, as well as a Kaluza-Klein graviton with mass below 2.3 TeV.

Observation of Higgs boson production in association with a top quark pair at the LHC with the ATLAS detector

Fri 14 Jun 2019 09:37:33 KRAT

The observation of Higgs boson production in association with a top quark pair (tt¯H), based on the analysis of proton–proton collision data at a centre-of-massenergy of 13 TeV recorded with the ATLAS detector at the Large Hadron Collider, is presented. Using data corresponding to integrated luminosities of up to 79.8 fb−1, and considering Higgs boson decays into bb¯, ⁎WW⁎, τ+τ−, γγ, and ⁎ZZ⁎, the observed significance is 5.8 standard deviations, compared to an expectation of 4.9 standard deviations. Combined with the tt¯H searches using a dataset corresponding to integrated luminosities of 4.5 fb−1 at 7 TeV and 20.3 fb−1 at 8 TeV, the observed (expected) significance is 6.3 (5.1) standard deviations. Assuming Standard Model branching fractions, the total tt¯H production cross section at 13 TeV is measured to be 670 ± 90 (stat.) −100+110 (syst.) fb, in agreement with the Standard Model prediction.

Observation of centrality-dependent acoplanarity for muon pairs produced via two-photon scattering in Pb + Pb collisions at √sNN=5.02 TeV with the ATLAS detector

Fri 14 Jun 2019 09:30:42 KRAT

This Letter presents a measurement of γγ→μ+μ− production in Pb+Pb collisions recorded by the ATLAS detector at the Large Hadron Collider at √sNN=5.02 TeV with an integrated luminosity of 0.49 nb−1. The azimuthal angle and transverse momentum correlations between the muons are measured as a function of collision centrality. The muon pairs are produced from γγ through the interaction of the large electromagnetic fields of the nuclei. The contribution from background sources of muon pairs is removed using a template fit method. In peripheral collisions, the muons exhibit a strong back-to-back correlation consistent with previous measurements of muon pair production in ultraperipheral collisions. The angular correlations are observed to broaden significantly in central collisions. The modifications are qualitatively consistent with rescattering of the muons while passing through the hot matter produced in the collision.

Search for heavy resonances decaying into a W or Z boson and a Higgs boson in final states with leptons and b-jets in 36 fb-1 of √s = 13 TeV pp collisions with the ATLAS detector

Fri 14 Jun 2019 09:30:38 KRAT

A search is conducted for new resonances decaying into a W or Z boson and a 125 GeV Higgs boson in the

Search for lepton-flavor-violating decays of the Z boson into a τ lepton and a light lepton with the ATLAS detector

Fri 14 Jun 2019 09:30:37 KRAT

Direct searches for lepton flavor violation in decays of the Z boson with the ATLAS detector at the LHC are presented. Decays of the Z boson into an electron or muon and a hadronically decaying τ lepton are considered. The searches are based on a data sample of proton-proton collisions collected by the ATLAS detector in 2015 and 2016, corresponding to an integrated luminosity of 36.1 fb−1 at a center-of-mass energy of √s=13 TeV. No statistically significant excess of events above the expected background is observed, and upper limits on the branching ratios of lepton-flavor-violating decays are set at the 95% confidence level: B(Z→eτ)<5.8×10−5 and B(Z→μτ)<2.4×10−5. This is the first limit on B(Z→eτ) with ATLAS data. The upper limit on B(Z→μτ) is combined with a previous ATLAS result based on 20.3 fb−1 of proton-proton collision data at a center-of-mass energy of √s=8 TeV and the combined upper limit at 95% confidence level is B(Z→μτ)<1.3×10−5.

Search for Higgs boson pair production in the γγb¯b final state with 13 TeV pp collision data collected by the ATLAS experiment

Fri 14 Jun 2019 09:30:32 KRAT

A search is performed for resonant and non-resonant Higgs boson pair production in the γγbb¯¯γγbb¯final state. The data set used corresponds to an integrated luminosity of 36.1 fb−1 of proton-proton collisions at a centre-of-mass energy of 13 TeV recorded by the ATLAS detector at the CERN Large Hadron Collider. No significant excess relative to the Standard Model expectation is observed. The observed limit on the non-resonant Higgs boson pair cross-section is 0.73 pb at 95% confidence level. This observed limit is equivalent to 22 times the predicted Standard Model cross-section. The Higgs boson self-coupling (κλ = λHHH/λ HHH SM ) is constrained at 95% confidence level to −8.2 < κλ < 13.2. For resonant Higgs boson pair production through X→HH→γγbb¯¯X→HH→γγbb¯, the limit is presented, using the narrow-width approximation, as a function of mX in the range 260 GeV < mX < 1000 GeV. The observed limits range from 1.1 pb to 0.12 pb over this mass range.

Оценка моментов появления и исчезновения оптического импульса с прямоугольным профилем интенсивности неизвестной высоты

Fri 11 Jan 2019 09:36:24 KRAT

Выполнены синтез и анализ квазиправдоподобного, максимально правдоподобного и квазиоптимального алгоритмов оценок моментов появления и исчезновения оптического импульса с прямоугольным профилем интенсивности неизвестной высоты. Найдены потери в точности оценок вследствие априорного незнания интенсивности оптического импульса.

Search for exclusive Higgs and Z boson decays to фγ and ργ with the ATLAS detector

Fri 07 Jun 2019 10:02:08 KRAT

A search for the exclusive decays of the Higgs and Z bosons to a ϕ or ρ meson and a photon is performed with a pp collision data sample corresponding to an integrated luminosity of up to 35.6 fb−1 collected at sqrt{s}=13 TeV with the ATLAS detector at the CERN Large Hadron Collider. These decays have been suggested as a probe of the Higgs boson couplings to light quarks. No significant excess of events is observed above the background, as expected from the Standard Model. Upper limits at 95% confidence level were obtained on the branching fractions of the Higgs boson decays to ϕγ and ργ of 4.8 × 10−4 and 8.8 × 10−4, respectively. The corresponding 95% confidence level upper limits for the Z boson decays are 0.9 × 10−6 and 25 × 10−6 for ϕγ and ργ, respectively.

Унитарное квантование и параферми-статистика порядка 2

Fri 02 Nov 2018 11:01:56 KRAT

Рассмотрена связь между схемой унитарного квантования и параферми-статистикой порядка 2. Предложено соответствующее обобщение анзаца Грина, которое позволило обратить в тождество билинейные и трилинейные соотношения для операторов рождения и уничтожения двух различных параферми-полей, φ a и φ b. Предложен способ включения параграссмановых чисел ξ k в общую схему унитарного квантования. Для парастатистики порядка 2 обнаружен интересный факт, что трилинейные соотношения, содержащие как параграссмановы переменные ξ k, так и операторы поля ak, bm, при некотором обратимом отображении переходят в унитарно эквивалентные соотношения, в которых коммутаторы заменяются на антикоммутаторы и наоборот. Показано, что следствием данного обстоятельства является существование двух альтернативных определений когерентного состояния для параферми-осцилляторов. В явном виде построено преобразование Клейна для гриновских компонент операторов ak и bm, что позволило привести исходные коммутационные правила для компонент к нормальным коммутационным соотношениям для обычных ферми-полей. Проанализирована нетривиальная связь между трилинейными коммутационными соотношениями схемы унитарного квантования и так называемой тройной суперлиевой системой. Проведено краткое обсуждение возможности включения теории Дэффина-Кеммера-Петье в схему унитарного квантования.

Effect of the KK̅ and ηη channels and interference phenomena in the two-pion and KK̅ transitions of charmonia and bottomonia

Fri 02 Nov 2018 10:47:48 KRAT

It is shown that the basic shape of dipion and KK̅ mass spectra in decays J/ψ→ϕ(ππ,KK̅), ψ (2S)→J/ψππ, Y(4260)→J/ψ π π and in the two-pion transitions of bottomonia states are explained by an unified mechanism based on the contribution ofthe ππ, KK̅ and η η coupled channels including their interference. The role of the individual f0 resonances in making up the shape of the dipion mass distributions in the charmonia and bottomonia decays is considered.

Electromagnetic structure of nucleon and Roper in soft-wall AdS/QCD

Fri 02 Nov 2018 10:47:47 KRAT

We present an improved study of the electromagnetic form factors of the nucleon and of the Roper-nucleon transition using an extended version of the effective action of soft-wall AdS/QCD. We include novel contribution from additional nonminimal terms, which do not renormalize the charge and do not change the normalization of the corresponding form factors, but the inclusion of these terms results in an important contribution to the momentum dependence of the form factors and helicity amplitudes.

Конфлюэнтные гипергеометрические функции многих переменных и их применение к нахождению фундаментальных решений обобщенного уравнения Гельмгольца с сингулярными коэффициентами

Fri 02 Nov 2018 10:47:44 KRAT

Вводится в рассмотрение новый класс конфлюэнтных гипергеометрических функций многих переменных, изучаются их свойства, строятся интегральные представления и определяется система уравнений с частными производными, которую удовлетворяет данная функция. Оказывается, все фундаментальные решения обобщенного уравнения Гельмгольца с несколькими сингулярными коэффициентами выписываются через нововведенную конфлюэнтную гипергеометрическую функцию. С помощью установленной здесь формулы разложения для конфлюэнтной функции определен порядок особенности фундаментальных решений рассматриваемого эллиптического уравнения.