584 research outputs found
Semiclassical Study of Baryon and Lepton Number Violation in High-Energy Electroweak Collisions
We make use of a semiclassical method for calculating the suppression
exponent for topology changing transitions in high-energy electroweak
collisions. In the Standard Model these processes are accompanied by violation
of baryon and lepton number. By using a suitable computational technique we
obtain results for s-wave scattering in a large region of initial data. Our
results show that baryon and lepton number violation remains exponentially
suppressed up to very high energies of at least 30 sphaleron masses (250 TeV).
We also conclude that the known analytic approaches inferred from low energy
expansion provide reasonably good approximations up to the sphaleron energy (8
TeV) only.Comment: 23 pages, 18 figures. Phys.Rev.D journal version (two references
added
Charmed particles production in pA-interactions at 70 GeV
The results of the SERP-E-184 experiment at the U-70 accelerator (IHEP,
Protvino) are presented. Interactions of the 70 GeV proton beam with carbon,
silicon and lead targets were studied to detect decays of charmed , , , mesons and baryon near their production
threshold. Measurements of lifetimes and masses have shown a good agreement
with PDG data. The inclusive cross sections of charm production and their
A-dependencies have been obtained. The yields of these particles are compared
with the theoretical predictions and the data of other experiments. The
measured cross section of the total open charm production b/nucleon at the collision c.m. energy
= 11.8 GeV is well above the QCD model predictions. The contributions
of different kinds of charmed particles to the total cross section of the open
charm production in proton-nucleus interactions vary with energy.Comment: Presented at 19th International Seminar on High Energy Physics
QUARKS-2016 (Pushkin, Russia, 29 May - 4 June, 2016.). 11 pages, 9 figure
Yang-Lee Zeros of the Two- and Three-State Potts Model Defined on Feynman Diagrams
We present both analytic and numerical results on the position of the
partition function zeros on the complex magnetic field plane of the
(Ising) and states Potts model defined on Feynman diagrams
(thin random graphs). Our analytic results are based on the ideas of
destructive interference of coexisting phases and low temperature expansions.
For the case of the Ising model an argument based on a symmetry of the saddle
point equations leads us to a nonperturbative proof that the Yang-Lee zeros are
located on the unit circle, although no circle theorem is known in this case of
random graphs. For the states Potts model our perturbative results
indicate that the Yang-Lee zeros lie outside the unit circle. Both analytic
results are confirmed by finite lattice numerical calculations.Comment: 16 pages, 2 figures. Third version: the title was slightly changed.
To be published in Physical Review
Ferromagnetic properties of charged vector boson condensate
Bose-Einstein condensation of W bosons in the early universe is studied. It
is shown that, in the broken phase of the standard electroweak theory,
condensed W bosons form a ferromagnetic state with aligned spins. In this case
the primeval plasma may be spontaneously magnetized inside macroscopically
large domains and form magnetic fields which may be seeds for the observed
today galactic and intergalactic fields. However, in a modified theory, e.g. in
a theory without quartic self interactions of gauge bosons or for a smaller
value of the weak mixing angle, antiferromagnetic condensation is possible. In
the latter case W bosons form scalar condensate with macroscopically large
electric charge density i.e. with a large average value of the bilinear product
of W-vector fields but with microscopically small average value of the field
itself.Comment: Some numerical estimates and discussions are added according to the
referee's suggestions. This version is accepted for publication in JCA
Повышение виброустойчивости строительной и горной техники
On an example of the boring rig the technique of search of algorithm of control by active dampers power bodies from a condition of the basic units of a machine design vibrations level limitation is considered. Technique is applicable to road-building, construction site and mine machines having similar dynamic structures.На примере бурового станка рассмотрена методика поиска алгоритма управления силовыми органами активных гасителей колебаний из условия ограничения уровня вибраций основных узлов конструкции. Методика применима к дорожным, строительным и горным машинам, имеющим аналогичные динамические структуры
Preface: “Quarks-2016”, 19th International Seminar on High Energy Physics
The highlights of the most recent CMS results with 13 TeV data will be presented in this overview. The Standard Model precision measurements, including the top quark production, will be shown first. This will be followed by the presentation of Higgs boson studies with the early 13 TeV data. Then the focus will shift to searches for physics beyond the Standard Model, including the searches for several Supersymmetric scenarios, using different analysis techniques. The talk will conclude with searches for the exotic resonances, with an emphasis on studies of the high-mass diphoton production
Influence of the Ratio of Metal Composed Nanocomposites Fe-Co / C on Phase Composition
Metalcarbon nanocomposites based on polyacrylonitrile and nickel chloride are synthesized under the influence of infrared heat. The resulting materials represent a system of carbon matrix formed during the carbonization of PAN, and distributed in it nickel nanoparticles. The average size of the nanoparticles in the nanocomposite was 15-25 nm. It was found that the distribution of nickel nanoparticles sizes is determined by temperature synthesis nanocomposite. Thus with increasing temperature, the predominant average particle size of the metal increases, and the distribution is spread and shifted toward larger sizes.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3360
Scaling laws in hadronic processes and string theory
We propose a possible scheme for getting the known QCD scaling laws within
string theory. In particular, we consider amplitudes for exclusive scattering
of hadrons at large momentum transfer, hadronic form factors and distribution
functions.Comment: 13 pages, 2 figures, a comment and a reference added, a final version
to appear in Physical Review
Gauge/string duality and scalar glueball mass ratios
It has been shown by Polchinski and Strassler that the scaling of high energy
QCD scattering amplitudes can be obtained from string theory. They considered
an AdS slice as an approximation for the dual space of a confining gauge
theory. Here we use this approximation to estimate in a very simple way the
ratios of scalar glueball masses imposing Dirichlet boundary conditions on the
string dilaton field. These ratios are in good agreement with the results in
the literature. We also find that they do not depend on the size of the slice.Comment: 5 pages, no figures. References updated. Version published in JHE
The Process " Pbar P -> E- E+ " with Polarized Initial Particles and Proton Form Factors in Time-Like Region
The discussion on the asymptotical behaviour of the form factors in the
space-like and time-like regions have been corrected and clarified. Fig.3 has
been replaced by an improved analysis of the data.Comment: DFTT 13/93. LaTeX file, 11 pages + 3 figures (included
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