5,107 research outputs found
Realistic calculations of nuclear disappearance lifetimes induced by neutron-antineutron oscillations
Realistic calculations of nuclear disappearance lifetimes induced by
neutron-antineutron oscillations are reported for oxygen and iron, using
antineutron nuclear potentials derived from a recent comprehensive analysis of
antiproton atomic X-ray and radiochemical data. A lower limit of 3.3 x 10E8 s
on the neutron-antineutron oscillation time is derived from the
Super-Kamiokande I new lower limit of 1.77 x 10E32 yr on the neutron lifetime
in oxygen. Antineutron scattering lengths in carbon and nickel, needed in trap
experiments using ultracold neutrons, are calculated from updated antinucleon
optical potentials at threshold, with results shown to be largely model
independent.Comment: version matching PRD publication, typos and references correcte
Cosmic Coincidence and Asymmetric Dark Matter in a Stueckelberg Extension
We discuss the possibility of cogenesis generating the ratio of baryon
asymmetry to dark matter in a Stueckelberg U(1) extension of the standard model
and of the minimal supersymmetric standard model. For the U(1) we choose
which is anomaly free and can be gauged. The dark matter
candidate arising from this extension is a singlet of the standard model gauge
group but is charged under . Solutions to the Boltzmann
equations for relics in the presence of asymmetric dark matter are discussed.
It is shown that the ratio of the baryon asymmetry to dark matter consistent
with the current WMAP data, i.e., the cosmic coincidence, can be successfully
explained in this model with the depletion of the symmetric component of dark
matter from resonant annihilation via the Stueckelberg gauge boson. For the
extended MSSM model it is shown that one has a two component dark matter
picture with asymmetric dark matter being the dominant component and the
neutralino being the subdominant component (i.e., with relic density a small
fraction of the WMAP cold dark matter value). Remarkably, the subdominant
component can be detected in direct detection experiments such as SuperCDMS and
XENON-100. Further, it is shown that the class of Stueckelberg models with a
gauged will produce a dramatic signature at a muon collider
with the showing a detectable
resonance while is devoid of this
resonance. Asymmetric dark matter arising from a Stueckelberg
extension is also briefly discussed. Finally, in the models we propose the
asymmetric dark matter does not oscillate and there is no danger of it being
washed out from oscillations.Comment: 36 pages, 7 figure
Информационная поддержка анализа навыков и умений контингента студентов высшего учебного заведения
In the below article, the application of the fuzzy logical conclusion method is considered as decision-maker in the process of analyzing the students skills and abilities based on the requirements of potential employers, in order to reduce the time of the first interview for potential candidates on a vacant position. When analyzing the results of the assessment of the competence of university students, a certain degree of fuzziness arises. In modern practice, fuzzy logic is used in many different assessment methods, including questioning, interviewing, testing, descriptive method, classification method, pairwise comparison, rating method, business games competence models, and the like. Each of the methods has its advantages and disadvantages, but they are effective only as part of a unified personnel management system. As a method for implementing a systematic approach to the assessment of the contingent of students, it is proposed to use fuzzy logic, a mathematical apparatus that allows you to build a model of an object based on fuzzy judgments. The use of fuzzy logic, the mathematical apparatus of which allows you to build a model of the object, based on fuzzy reasoning and rules. The most important condition for creating such a model is to translate the fuzzy, qualitative assessments used by man into the language of mathematics, which will be understood by the computer. The most used are fuzzy inferences using the Mamdani and Sugeno methods. In a fuzzy inference of the Mamdani type, the value of the output variable is given by fuzzy terms, in the conclusion of the Sugeno type, as a linear combination of the input variables. Research in the field of application of fuzzy logic in socio-economic systems suggests that it can be used to assess the competencies of university students.В данной работе рассмотрено использование метода нечеткого логического вывода для поддержки принятия решения в задачах анализа навыков и умений контингента студентов исходя из требований потенциальных работодателей, с целью уменьшения времени на первичную обработку информации касательно потенциальных кандидатов на вакантную должность. При анализе результатов оценки компетентности студентов вузов возникает определенная степень нечеткости. В современной практике нечеткая логика применяется во многих различных методах оценки, в том числе анкетирование, интервью, тестирование, описательный метод, метод классификации, парное сравнение, рейтинговый метод, деловые игры модели компетентности и тому подобное. Каждый из методов имеет свои преимущества и недостатки, но эффективны они только в составе единой системы управления персоналом. Как метод для реализации системного подхода к оценке контингента студентов предложено использовать нечеткую логику, математический аппарат, который позволяет построить модель объекта, основанную на нечетких суждениях. Использование нечеткой логики, математический аппарат которой позволяет построить модель объекта, основываясь на нечетких рассуждениях и правилах. Важнейшее условие создания такой модели заключается в том, чтобы перевести нечеткие, качественные оценки, применяемые человеком, на язык математики, которая будет понятна вычислительной машине. Наиболее используемыми являются нечеткие выводы с помощью способов Мамдани и Сугено. В нечетком выводе типа Мамдани значение выходной переменной задаются нечеткими термами, в заключении типа Сугено – как линейная комбинация входных переменных. Исследования в области применения нечеткой логики в социоэкономических системах позволяют говорить о возможности ее использования для оценки компетенций студентов вузов
Non-compensation of an Electromagnetic Compartment of a Combined Calorimeter
The method of extraction of the ratio, the degree of non-compensation,
of the electromagnetic compartment of the combined calorimeter is suggested.
The ratio of has been determined on the basis of the 1996
combined calorimeter test beam data. This value agrees with the prediction that
for this electromagnetic calorimeter.Comment: LATEX, 17 pages, 7 figure
Longitudinal Hadronic Shower Development in a Combined Calorimeter
This work is devoted to the experimental study of the longitudinal hadronic
shower development in the ATLAS barrel combined prototype calorimeter
consisting of the lead-liquid argon electromagnetic part and the
iron-scintillator hadronic part. The results have been obtained on the basis of
the 1996 combined test beam data which have been taken on the H8 beam of the
CERN SPS, with the pion beams of 10, 20, 40, 50, 80, 100, 150 and 300 GeV/c.
The degree of description of generally accepted Bock parameterization of the
longitudinal shower development has been investigated. It is shown that this
parameterization does not give satisfactory description for this combined
calorimeter. Some modification of this parameterization, in which the e/h
ratios of the compartments of the combined calorimeter are used, is suggested
and compared with the experimental data. The agreement between such
parameterization and the experimental data is demonstrated.Comment: Latex, 21 pages, 10 figure
Non-perturbative proton stability
Proton decay is a generic prediction of GUT models and is therefore an
important channel to detect the existence of unification or to set limits on
GUT models. Current bounds on the proton lifetime are around 10^33 years, which
sets stringent limits on the GUT scale. These limits are obtained under
`reasonable' assumptions about the size of the hadronic matrix elements. In
this paper we present a non-perturbative calculation of the hadronic matrix
elements within the chiral bag model of the proton. We argue that there is an
exponential suppression of the matrix elements, due to non-perturbative QCD,
that stifles proton decay by orders of magnitude -- potentially O(10^-10). This
suppression is present for small quark masses and is due to the chiral symmetry
breaking of QCD. Such a suppression has clear implications for GUT models and
could resuscitate several scenarios
Neutrino-nucleon cross sections at energies of Megaton-scale detectors
An updated set of (anti)neutrino-nucleon charged and neutral current cross
sections at is presented.
These cross sections are of particular interest for the detector optimization
and data processing and interpretation in the future Megaton-scale experiments
like PINGU, ORCA, and Hyper-Kamiokande. Finite masses of charged leptons and
target mass corrections in exclusive and deep inelastic
interactions are taken into account. A new set of QCD NNLO parton density
functions, the ABMP15, is used for calculation of the DIS cross sections. The
sensitivity of the cross sections to phenomenological parameters and to
extrapolations of the nucleon structure functions to small and is
studied. An agreement within the uncertainties of our calculations with
experimental data is demonstrated.Comment: 4 pages, 4 figures, accepted for the VLVnT-2015 Conference
proceedings, will be published on EPJ Web of Conference
A remark on sphaleron erasure of baryon asymmetry
We complete an existing result for how the baryon asymmetry left over after a
period of full thermal equilibrium depends on different lepton asymmetries.Comment: 5 pages; small clarifications and a reference added; to appear in PR
The Electroweak Phase Transition in Ultra Minimal Technicolor
We unveil the temperature-dependent electroweak phase transition in new
extensions of the Standard Model in which the electroweak symmetry is
spontaneously broken via strongly coupled, nearly-conformal dynamics achieved
by the means of multiple matter representations. In particular, we focus on the
low energy effective theory introduced to describe Ultra Minimal Walking
Technicolor at the phase transition. Using the one-loop effective potential
with ring improvement, we identify regions of parameter space which yield a
strong first order transition. A striking feature of the model is the existence
of a second phase transition associated to the electroweak-singlet sector. The
interplay between these two transitions leads to an extremely rich phase
diagram.Comment: 38 RevTeX pages, 9 figure
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