arXiv subjects

E. G. Drukarev

Publications and source records attributed to E. G. Drukarev.

43 records · Page 3Linked to original sources

arXiv2003

Finite density QCD sum rules for nucleons

It is shown how the QCD sum rules can be applied for the investigation of the density dependence of the nucleon parameters. These characteristics can be expressed through the expectation values of QCD operators in nuclear matter. In certain approximations the expectation values are related to the observables. First applications of the approach reproduced some of the basic features of nuclear physics, providing also a new knowledge. The program of the future work is presented. The difficulties of the approach are discussed.

hep-ph↗

arXiv2002

Expectation values of four-quark operators in pions

The values of four-quark operators averaged over pions are expressed through those averaged over vacuum. The specific values are obtained in the framework of the factorization assumption. For the condensates of the light quarks of the same flavour \bar qΓq\bar qΓq the scalar condensate is shown to be an order of magnitude larger than the other ones. The condensates containing the strange quarks \bar q q\bar s s appear to be only about twice smaller than those of the light quarks. The degeneracy of the ground state in the Nambu--Jona--Lasinio model is shown explicitly.

hep-ph↗

arXiv2001

QCD condensates and hadron parameters in nuclear matter: self-consistent treatment, sum rules and all that

We review various approaches to the calculation of QCD condensates and of the nucleon characteristics in nuclear matter. We show the importance of their self-consistent treatment. The first steps in such treatment appeared to be very instructive. It is shown that the alleged pion condensation anyway can not take place earlier than the restoration of the chiral symmetry. We demonstrate how the finite density QCD sum rules for nucleons work and advocate their possible role in providing an additional bridge between the condensate and hadron physics.

nucl-th↗

arXiv2000

Sigma-term physics in the perturbative chiral quark model

We apply the perturbative chiral quark model (PCQM) at one loop to analyse meson-baryon sigma-terms. Analytic expressions for these quantities are obtained in terms of fundamental parameters of low-energy pion-nucleon physics (weak pion decay constant, axial nucleon coupling, strong pion-nucleon form factor) and of only one model parameter (radius of the nucleonic three-quark core). Our result for the piN sigma term of about 45 MeV is in good agreement with the value deduced by Gasser, Leutwyler and Sainio using dispersion-relation techniques and exploiting the chiral symmetry constraints.

hep-ph↗

arXiv1998

Self-consistent treatment of the quark condensate and hadrons in nuclear matter

We calculate the contribution of pions to the $\bar qq$-expectation value $κ(ρ)= $ in symmetric nuclear matter. We employ exact pion propagator renormalized by nucleon-hole and isobar-hole excitations. Conventional straightforward calculation leads to the "pion condensation" at unrealistically small values of densities, causing even earlier restoration of chiral symmetry. This requires a self-consistent approach, consisting in using the models, which include direct dependence of in-medium mass values on $κ(ρ)$, e.g. the Nambu-Jona-Lasinio-model. We show, that in the self-consistent approach the $ρ$-dependence of the condensate is described by a smooth curve. The "pion condensate " point is removed to much higher values of density. The chiral restoration does not take place at least while $ρ<2.8ρ_0$ with $ρ_0$ being the saturation value. Validity of our approach is limited by possible accumulation of heavier baryons (delta isobars) in the ground state of nuclear matter. For the value of effective nucleon mass at the saturation density we found $m^*(ρ_0)=0.6m$, consistent with nowadays results of other authors.

hep-ph↗

arXiv1997

QCD sum rules as a tool for investigation of characteristics of a nucleon in nuclear matter

We analyse the calculations of deep inelastic structure functions of free nucleons by QCD sum rules method,carried out by others.We present our results of calculation of the distribution of valence quarks in nucleon placed into the nuclear matter.We show that the change in distribution has typical EMC shape.We discuss possible application of the method to investiga- tion of other aspects of deep-inelastic processes.We analyse also the limits of possibilities of the approach.

hep-ph↗

arXiv1997

QCD sum rules as a tool for investigation of the baryon properties at finite densities

We analyse the calculations of deep inelastic structure functions of free nucleons by QCD sum rules method,carried out by others.We present our results of calculation of the distribution of valence quarks in nucleon placed into the nuclear matter.We show that the change in distribution has typical EMC shape.We discuss possible application of the method to investigation of other aspects of deep-inelastic processes.We analyse also the limits of possibilities of the approach.

hep-ph↗