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M. Polyakov

Publications and source records attributed to M. Polyakov.

7 recordsLinked to original sources
arXiv2010

The Description of Spatial Characteristics of Elastic Processes in the Wigner Function Formalism

The Wigner function formalism has been applied to the analysis of elastic scattering processes. The new element of known formalism is the choice of the phase space on which the Wigner function is defined. This phase space is 4-dimensional space of canonically conjugate variables - the transverse momentum of scattered particle and the projection of the vector of the closest approach of particles in the plane which is perpendicular to the momentum of initial particle. The exact expression for the mean value of the scattered particles production area radius through a scattering amplitude has been obtained.

hep-ph↗
arXiv2000

On the azimuthal asymmetries in DIS

Using the recent experimental data on the left right asymmetry in fragmentation of transversely polarized quarks and the theoretical calculation of the proton transversity distribution in the effective chiral quark soliton model we explain the azimuthal asymmetries in semi-inclusive hadron production on longitudinal (HERMES) and transversely (SMC) polarized targets with no free parameters. On this basis we state that the proton transversity distribution could be successfully measured in future DIS experiments with longitudinally polarized target.

hep-ph↗
arXiv1996

Nucleon Parton Distributions at Low Normalization Point in the Large N_c Limit

At large N_c the nucleon can be viewed as a soliton of the effective chiral lagrangian. This picture of nucleons allows a consistent nonperturbative calculation of the leading-twist parton distributions at a low normalization point. We derive general formulae for the polarized and unpolarized distributions (singlet and non-singlet) in the chiral quark-soliton model. The consistency of our approach is demonstrated by checking the baryon number, isospin and total momentum sum rules, as well as the Bjorken sum rule. We present numerical estimates of the quark and antiquark distributions and find reasonable agreement with parametrizations of the data at a low normalization point. In particular, we obtain a sizeable fraction of antiquarks, in agreement with the phenomenological analysis.

hep-ph↗
arXiv1995

Sphaleron transitions in the Minimal Standard Model and the upper bound for the Higgs Mass

We calculate the dissipation of the baryon number after the electroweak phase transition due to thermal fluctuations above the sphaleron barrier. We consider not only the classical Boltzmann factor but also fermionic and bosonic one-loop contributions. We find that both bosonic and especially fermionic fluctuations can considerably suppress the transition rate. Assuming the Langer--Affleck formalism for this rate, the condition that an initial baryon asymmetry must not be washed out by sphaleron transitions leads, in the Minimal Standard Model ($\sinθ_W=0$), to an upper bound for the Higgs mass in the range 60 to 75 GeV.

hep-ph↗
arXiv1995

NJL model with vector couplings vs. phenomenology

We study the pseudoscalar, vector and axial current correlation functions in SU(2)-NJL model with scalar and vector couplings. The correlation functions are evaluated in leading order in number of colors $N_c$. As it is expected in the pseudoscalar channel pions appear as Goldstone bosons, and after fixing the cutoff to reproduce the physical pion decay constant, we obtain well-known current-algebra results. For the vector and axial channels we use essentially that at spacelike momenta the correlation functions can be related to the experimentally known spectral density via dispersion relations. We show that the latter imposes strong bounds on the strength of the vector coupling in the model. We find that the commonly used on-shell treatment of the vector and axial mesons (identified as poles at large timelike momenta) fails to reproduce the behavior of the corresponding correlation functions at small spacelike momenta extracted from the physical spectral density. The parameters of the NJL model fixed by the correlation functions at small spacelike momenta differ noticeably from those of the on-shell treatment.

hep-ph↗
arXiv1994

${\bar p} p$ Annihilation: Manifestations of Instanton Induced Quark Pair Production ?

Production of strangeness in the low-energy ${\bar p} p$ annihilation is analyzed as a manifestation of the instanton induced multiquark vertex. Approach based on the {\it qualitative} properties of the 't Hooft mechanism provides a unified description of available experimental data on $K$- and $ϕ$-meson production. Crucial tests for the hypothesized mechanism are suggested.

hep-ph↗