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E. G. Drukarev

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

At least 19 recordsLinked to original sources
arXiv2020

Relativistic photoeffect for $s$ states in a central field

We study the photoionization of the $s$ states in the systems bound by sufficiently weak central fields $V(r)$ for the large photon energies corresponding to the relativistic photoelectrons. We demonstrate that the energy dependence of the photoionization cross section can be obtained without solving the wave equation. We show that the shape of the energy dependence of the cross section is determined by analytical properties of the binding potential $V(r)$. We find the cross sections for the potentials $V(r)$ which have singularities in the origin, on the real axis and in the complex plane.

hep-ph↗
arXiv2018

Asymptotic behavior of photoionization cross section in a central field. Ionization of the $p$ states

We continue our studies of the high energy nonrelativistic asymptotics for the photoionization cross section of the systems bound by a central field $V(r)$. We consider the bound states with the orbital momentum $\ell=1$. We show, that as well as for the $s$ states the asymptotics can be obtained without solving of the wave equations for the bound and outgoing electrons. The asymptotics of the cross sections is expressed in terms of the asymptotics of the Fourier transform $V(p)$ of the field and its derivative $V'(p)$ by employing the Lippmann--Schwinger equation. The shape of the energy dependence of the cross sections is determined by the analytical properties of the potential $V(r)$. The cross sections exhibit power drop with the increase of the photon energy for the potentials $V(r)$ which have singularities on the real axis. They experience exponential drop if $V(r)$ has poles in the complex plane. We trace the energy dependence of the ratios of the photoionization cross sections for $s$ and $p$ electrons from the states with the same principle quantum number. We apply the results to the physics of fullerenes.

physics.atom-ph↗
arXiv2018

Equilibrium of nuclear matter in QCD sum rules

We calculate the nucleon parameters in symmetric nuclear matter employing the QCD sum rules approach. We focus on the average energy per nucleon and study the equilibrium states of the matter. We treat the matter as a relativistic system of interacting nucleons. Assuming the dependence of the nucleon mass on the light quark mass $m_q$ to be more important than that of nucleon interactions we find that the contribution of the relativistic nucleons to the scalar quark condensate can be expressed as that caused by free nucleons at rest multiplied by the density dependent factor $F(ρ)$. We demonstrate that there are no equilibrium states while we include only the condensates with dimension $d \leq 3$. There are equilibrium states if we include the lowest order radiative corrections and the condensates with $d \leq 4$. They manifest themselves for the nucleon sigma term $σ_N >60$ MeV. Including the condensates with $ d \leq 6$ we find equilibrium states of nuclear matter for $σ_N> 41$ MeV. In all cases the equilibrium states are due to influence of the relativistic motion of the nucleons composing the matter on the scalar quark condensate.

nucl-th↗
arXiv2018

Photoionization of the bound systems at high energies

We consider photoionization of a system bound by the central potential $V(r)$. We demonstrate that the high energy nonrelativistic asymptotics of the photoionization cross section can be obtained without solving the wave equation. The asymptotics can be expressed in terms of the Fourier transform of the potential by employing the Lippmann--Schwinger equation. We find the asymptotics for the screened Coulomb field. We demonstrate that the leading corrections to this asymptotics are described by the universal factor. The high energy nonrelativistic asymptotics is found to be determined by the analytic properties of the potential $V(r)$. We show that the energy dependence of the asymptotics of photoionization cross sections of fullerenes is to large extent model dependent. We demonstrate that if the fullerene field $V(r)$ is approximated by the function with singularities in the complex plane, the power drop of the asymptotics is reached at the energies which as so high that the cross section becomes unobservably small. The preasymptotic behavior with a faster drop of the cross sections becomes important in these cases.

physics.atom-ph↗
arXiv2017

High energy photoionization of fullerenes

We show that the theoretical predictions on high energy behavior of the photoionization cross section of fullerenes depends crucially on the form of the function $V(r)$ which approximates the fullerene field. The shape of the high energy cross section is obtained without solving of the wave equation. The cross section energy dependence is determined by the analytical properties of the function $V(r)$.

physics.atom-ph↗
arXiv2017

Many body effects in nuclear matter QCD sum rules

We calculate the single-particle nucleon characteristics in symmetric nuclear matter with inclusion of the 3N and 4N interactions. We calculated the contribution of the 3N interactions earlier, now we add that of the 4N ones. The contribution of the 4N forces to nucleon self energies is expressed in terms of the nonlocal scalar condensate (d=3) and of the configurations of the vector-scalar and the scalar-scalar quark condensates (d=6) in which two diquark operators act on two different nucleons of the matter.These four-quark condensates are obtained in the model-independent way. The density dependence of the nucleon effective mass, of the vector self energy and of the single-particle potential energy are obtained. We traced the dependence of the nucleon characteristics on the actual value of the pion-nucleon sigma term. We obtained also the nucleon characteristics in terms of the quasifree nucleons, with the noninteracting nucleons surrounded by their pion clouds as the starting point. This approach leads to strict hierarchy of the many body forces.

nucl-th↗
arXiv2017

Asymptotic behavior of photoionization cross section in a central field

We demonstrate that the high energy nonrelativistic asymptotic for the photoionization cross section in a central field $V(r)$ can be expressed in terms of the asymptotic of the Fourier transform $V(p)$ of the field. We show that the cross sections drop in the same way for the fields with the Coulomb short distance behavior. The character of the cross sections energy behavior is related to the analytical properties of the function $V(r)$. The cross sections exhibit power drop for the potentials which have singularities an the real axis. They suffer the exponential drop if $V(r)$ has singularities in the complex plane.

quant-ph↗
arXiv2016

Three nucleon forces in nuclear matter in the QCD sum rules

We calculate the single-particle nucleon characteristics in symmetric nuclear matter with inclusion of the 3N interactions. The contribution of the 3N forces to the nucleon self energies are expressed in terms of the nonlocal scalar condensate (d=3) and of the configuration of the two four-quark condensates (d=6) in which two diquark operators act on two different nucleons of the matter. The most important part of the contribution of the four-quark condensate is calculated in a model-independent way. We employed a relativistic quark model of nucleon for calculation of the rest part. The density dependence of the vector and scalar nucleon self energies and of the single-particle potential energy are obtained.

nucl-th↗
arXiv2016

On neutrinoless double electron capture

We found the probability for the neutrinoless double electron capture in the case of $KK$ capture. We clarified the mechanism of the energy transfer from the nucleus to the bound electrons. This enabled us to obtain the equations for the probability of the $2EC0ν$ process which modify those obtained earlier. We found that the probability of the process is three orders of magnitude larger than it was supposed earlier.

nucl-th↗
arXiv2015

Nucleon QCD sum rules in instanton medium

We try to find the grounds for the standard nucleon QCD sum rules, based on more detailed description of QCD vacuum. We calculate the polarization operator of the nucleon current in the instanton medium. The medium (QCD vacuum) is assumed to be a composition of the small-size instantons and some long-wave gluon fluctuations. We solve the corresponding QCD sum rules equations and demonstrate that there is a solution with the value of the nucleon mass close to the physical one if the fraction of the small size instantons contribution w_s \approx 2/3.

hep-ph↗
arXiv2015

Influence of the inner shell electrons on photoionization of outer shells

We have studied the role of virtual excitations of inner shells upon outer shell photoionization. The calculations were performed in the frames of the Random Phase Approximation and its generalized version GRPAE that take into account variation of the atomic field due to electron elimination and the inner vacancies decay. We employ both analytic approximation and numeric computations. The results are presented for 3p electrons in Ar and 4d-electrons in Pd near inner shells thresholds. The effect proved to be noticeable.

physics.atom-ph↗
arXiv2014

On the loop approximation in nucleon QCD sum rules

There was a general believe that the nucleon QCD sum rules which include only the quark loops and thus contain only the condensates of dimension d=3 and d=4 have only a trivial solution. We demonstrate that there is also a nontrivial solution. We show that it can be treated as the lowest order approximation to the solution which includes the higher terms of the Operator Product Expansion. Inclusion of the radiative corrections improves the convergence of the series.

hep-ph↗
arXiv2014

Nucleon QCD sum rules in instanton vacuum

We calculate the polarization operator of the nucleon current in the instanton medium. The medium (QCD vacuum) is assumed to be a composition of the instantons of large and small sizes. The former are described in terms of the local scalar condensate, while the latter can be interpreted as the nonlocal scalar condensate. We solve the corresponding QCD sum rules equations and demonstrate that there is a solution with the value of the nucleon mass close to the physical one if the fraction of the small size instantons w_s \approx 2/3.

hep-ph↗
arXiv2014

Non-locality of the scalar quark condensate

We suggest a somewhat indirect method for estimation of the nonlocal scalar quark condensate. The approach is based on analysis of the polarization operator of nucleon current in instanton medium.

hep-ph↗
arXiv2014

Explanation of the recent results on photoionization of endohedral atoms

We suggest an explanation of the recently observed discrepancy between the experimental and theoretical results on ionization of atoms, encapsulated into the fullerenes by photons with the energies of about 80-190eV. On the ground of previous theoretical considerations we conclude that the photoionization of the caged atom without excitation of the fullerene shell has low probability.

physics.atom-ph↗
arXiv2013

Dependence of nucleon mass on parameters of instanton medium

We trace the dependence of the nucleon mass and of the effective size of the nucleon on the characteristics of the instanton medium, which are the average instanton size $ρ$ and the distance between the instantons in instanton medium R. We consider several scenario for variation of the values of $ρ$ and R.

hep-ph↗
arXiv2013

On the dependence of one-photon - two-electron differential cross sections on recoil momenta

We calculate the distributions in recoil momenta and their energy distributions for the high energy non-relativistic double photoionization of helium caused by the quasifree mechanism of the process. The distributions obtain local maxima at small values of the recoil momenta. This is in agreement with the earlier predictions and with recently obtained experimental data. We obtained also the angular correlations, which reach the largest value in the "back-to-back" configuration of the photoelectrons. Our analysis is valid in all high energy nonrelativistic region. Particular equations are true for the case when the wavelength of the photon exceeds strongly the size of the atom. We present numerical results for the photon energies in the region of 1 keV, employed in the recent experiments.

physics.atom-ph↗