arXiv subjects

Alexander Bochkarev

Publications and source records attributed to Alexander Bochkarev.

4 recordsLinked to original sources

arXiv1996

Dispersive theory of charmonium on the Lattice

Physical contribution of the high-energy part of hadronic spectrum is incorporated to describe the short-distance part of the correlator of heavy-quark currents obtained by quenched Monte-Carlo on a $8^3*16$- and $16^3*32$-lattices for $β= \{ 6, 6.3 \}$. The lattice artifacts in the short-distance behavior of that correlator are isolated. The physical short-distance part of the correlator is fitted by the relevant expressions of perturbative QCD, which allows one to obtain the renormalized charmed quark mass with rather high accuracy $m_c^{\bar{MS}}(m_c)\,=\,1.22(5)\,GeV$.

hep-ph↗

arXiv1996

Chiral symmetry at finite temperature: linear vs nonlinear $σ$-models

The linear O($N$) sigma model undergoes a symmetry restoring phase transition at finite temperature. We show that the nonlinear O($N$) sigma model also undergoes a symmetry restoring phase transition; the critical temperatures are the same when the linear model is treated in mean field approximation and the nonlinear model is treated to leading plus subleading order in the 1/$N$ expansion. We also carefully define and study the behavior of $f_π$ and the scalar condensate at low temperatures in both models, showing that they are independent of field redefinition.

hep-ph↗

arXiv1995

On the reliable measurement of the gluon condensate in lattice QCD

We propose to calculate the gluon condensate in lattice QCD in an indirect way by extracting it from the correlator of hadronic currents of heavy quarks. Moments (derivatives with respect to momentum at vanishing momentum) of the vector and pseudoscalar correlators are evaluated. The contribution of the continuum spectrum in addition to the low-lying resonance is observed in accordance with qualitative expectations. Finite size effects are observed and shown to be insignificant for heavy quarks and moderate lattices. A practical definition of the nonperturbatively renormalized heavy quark mass is given.

hep-lat↗

arXiv1992

Nonperturbative evaluation of the diffusion rate in field theory at high temperatures

Kramer's approach to the rate of the thermally activated escape from a metastable state is extended to field theory. Diffusion rate in the 1+1-dimensional Sine-Gordon model as a function of temperature and friction coefficient is evaluated numerically by solving the Langevin equation in real time. A clear crossover from the semiclassical to the high temperature domain is observed. The temperature behaviour of the diffusion rate allows one to determine the kink mass which is found equal to the corresponding classical value. The Kramer's predictions for the dependence on viscosity are qualitatively valid in this multidimensional case. In the limit of vanishing friction the diffusion rate is shown to coincide with the one obtained from the direct measurements of the conventional classical real-time Green function at finite temperature.

hep-lat↗