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I. S. Terekhov

Publications and source records attributed to I. S. Terekhov.

32 records · Page 2Linked to original sources
arXiv2012

New quantum-mechanical phenomenon in a model of electron-electron interaction in graphene

A quantum mechanical model of two interacting electrons in graphene is considered. We concentrate on the case of zero total momentum of the pair. We show that the dynamics of the system is very unusual. Both stationary and time-dependent problems are considered. It is shown that the complete set of the wave functions with definite energy includes the new functions, previously overlooked. The time evolution of the wave packet, corresponding to the scattering problem setup, leads to the appearance of the localized state at large time. The asymptotics of this state is found analytically. We obtain the lower bound of the life time of this state, which is connected with the breakdown of the continuous model on the lattice scale. The estimate of this bound gives one a hope to observe the localized states in the experiment.

cond-mat.str-el↗
arXiv2011

Relativistic Coulomb Green's function in $d$-dimensions

Using the operator method, the Green's functions of the Dirac and Klein-Gordon equations in the Coulomb potential $-Zα/r$ are derived for the arbitrary space dimensionality $d$. Nonrelativistic and quasiclassical asymptotics of these Green's functions are considered in detail.

physics.atom-ph↗
arXiv2009

Induced Current and Aharonov-Bohm Effect in Graphene

The effect of vacuum polarization in the field of an infinitesimally thin solenoid at distances much larger than the radius of solenoid is investigated. The induced charge density and induced current are calculated. Though the induced charge density turned out to be zero, the induced current is finite periodical function of the magnetic flux $Φ$. The expression for this function is found exactly in a value of the flux. The induced current is equal to zero at the integer values of $Φ/Φ_0$ as well as at half-integer values of this ratio, where $Φ_0=2π\hbar c/e$ is the elementary magnetic flux. The latter is a consequence of the Furry theorem and periodicity of the induced current with respect to magnetic flux. As an example we consider the graphene in the field of solenoid perpendicular to the plane of a sample.

cond-mat.mes-hall↗
arXiv2008

Quasiclassical description of bremsstrahlung accompanying alpha decay including quadrupole radiation

We present a quasiclassical theory of alpha decay accompanied by bremsstrahlung with a special emphasis on the case of 210Po, with the aim of finding a unified description that incorporates both the radiation during the tunneling through the Coulomb wall and the finite energy E_gamma of the radiated photon up to E_gamma on the order of Q_alpha/sqrt(eta), where Q_alpha is the alpha-decay Q-value and eta is the Sommerfeld parameter. The corrections with respect to previous quasiclassical investigations are found to be substantial, and excellent agreement with a full quantum mechanical treatment is achieved. Furthermore, we find that a dipole-quadrupole interference significantly changes the alpha-gamma angular correlation. We obtain good agreement between our theoretical predictions and experimental results.

nucl-th↗
arXiv2007

Coulomb corrections to the Delbrueck scattering amplitude at low energies

In this article, we study the Coulomb corrections to the Delbrueck scattering amplitude. We consider the limit when the energy of the photon is much less than the electron mass. The calculations are carried out in the coordinate representation using the exact relativistic Green function of an electron in a Coulomb field. The resulting relative corrections are of the order of a few percent for scattering on for a large charge of the nucleus. We compare the corrections with the corresponding ones calculated through the dispersion integral of the pair production cross section and also with the magnetic loop contribution to the g-factor of a bound electron. The last one is in a good agreement with our results but the corrections calculated through the dispersion relation are not.

hep-ph↗
arXiv2007

Bremsstrahlung in alpha-Decay Reexamined

A high-statistics measurement of bremsstrahlung emitted in the alpha decay of 210Po has been performed, which allows to follow the photon spectra up to energies of ~ 500 keV. The measured differential emission probability is in good agreement with our theoretical results obtained within the quasi classical approximation as well as with the exact quantum mechanical calculation. It is shown that due to the small effective electric dipole charge of the radiating system a significant interference between the electric dipole and quadrupole contributions occurs, which is altering substantially the angular correlation between the alpha particle and the emitted photon.

nucl-ex↗
arXiv2005

Laser-dressed vacuum polarization in a Coulomb field

We investigate quantum electrodynamic effects under the influence of an external, time-dependent electromagnetic field, which mediates dynamic modifications of the radiative corrections. Specifically, we consider the quantum electrodynamic vacuum-polarization tensor under the influence of two external background fields: a strong laser field and a nuclear Coulomb field. We calculate the charge and current densities induced by a nuclear Coulomb field in the presence of a laser field. We find the corresponding induced scalar and vector potentials. The induced potential, in first-order perturbation theory, leads to a correction to atomic energy levels. The external laser field breaks the rotational symmetry of the system. Consequently, the induced charge density is not spherically symmetric, and the energy correction therefore leads to a "polarized Lamb shift." In particular, the laser generates an additional potential with a quadrupole moment. The corresponding laser-dressed vacuum-polarization potential behaves like 1/r**3 at large distances, unlike the Uehling potential that vanishes exponentially for large r. Our investigation might be useful for other situations where quantum field theoretic phenomena are subjected to external fields of a rather involved structure.

physics.atom-ph↗
arXiv2004

Virtual light-by-light scattering and the g factor of a bound electron

The contribution of the light-by-light diagram to the g factor of electron and muon bound in Coulomb field is obtained. For electron in a ground state, our results are in good agreement with the results of other authors obtained numerically for large Z. For relatively small Z our results have essentially higher accuracy as compared to the previous ones. For muonic atoms, the contribution is obtained for the first time with the high accuracy in whole region of Z.

hep-ph↗
arXiv2003

Finite nuclear size effect on Lamb shift of s1/2, p1/2, and p3/2 atomic states

We consider one-loop self-energy and vacuum polarization radiative corrections to the shift of atomic energy level due to finite nuclear size. Analytic expressions for vacuum polarization corrections are derived. For the self-energy of p1/2 and p3/2 states in addition to already known terms we derive next-to-leading nonlogarithmic Zα-terms. Together with contributions obtained earlier the terms derived in the present work give explicit analytic expressions for s1/2 and p1/2 corrections which agree with results of previous numerical calculations up to Z=100 (Z is the nuclear charge number). We also show that the finite nuclear size radiative correction for a p3/2 state is not small compared to the similar correction for a p1/2 state at least for small Z.

physics.atom-ph↗
arXiv2002

Calculation of radiative corrections to the effect of parity nonconservation in heavy atoms

We calculate the self-energy and the vertex radiative corrections to the effect of parity nonconservation in heavy atoms. The sum of the corrections is of the form ${\cal A}\ln(λ_C/r_0)+{\calB}$, where ${\cal A}$ and ${\cal B}$ are functions of $Zα$, and $λ_C$ and $r_0$ are the Compton wavelength and the nuclear radius, respectively. The function ${\cal A}$ is calculated exactly in $Zα$ and the function ${\cal B}$ is calculated in the leading order. In the leading order ${\cal A}\propto α(Zα)^2$ and ${\cal B}\propto α(Zα)$. The sum of the corrections is -0.85% for Cs and -1.48% for Tl. Using these results we have performed analysis of the experimental data on atomic parity nonconservation. The values obtained for the nuclear weak charge, $Q_W=-72.81(28)_{exp}(36)_{theor}$ for Cs and $Q_W=-116.8(1.2)_{exp}(3.4)_{theor}$ for Tl, agree with predictions of the standard model within $0.6σ$. As an application of our approach we have also calculated dependence of the Lamb shift on the finite nuclear size.

hep-ph↗
arXiv2002

Finite nuclear size and Lamb shift of p-wave atomic states

We consider corrections to the Lamb shift of p-wave atomic states due to the finite nuclear size (FNS). In other words, these are radiative corrections to the atomic isotop shift related to FNS. It is shown that the structure of the corrections is qualitatively different from that for s-wave states. The perturbation theory expansion for the relative correction for a $p_{1/2}$-state starts from $α\ln(1/Zα)$-term, while for $s_{1/2}$-states it starts from $Zα^2$ term. Here $α$ is the fine structure constant and $Z$ is the nuclear charge. In the present work we calculate the $α$-terms for $2p$-states, the result for $2p_{1/2}$-state reads $(8α/9π)[\ln(1/(Zα)^2)+0.710]$. Even more interesting are $p_{3/2}$-states. In this case the ``correction'' is by several orders of magnitude larger than the ``leading'' FNS shift.

physics.atom-ph↗
arXiv2002

Radiative corrections and parity nonconservation in heavy atoms

The self-energy and the vertex radiative corrections to the effect of parity nonconservation in heavy atoms are calculated analytically in orders Z alpha^2 and Z^2 alpha^3 ln(lambda_C/r_0), where lambda_C and r_0 being the Compton wavelength and the nuclear radius, respectively. The value of the radiative correction is -0.85% for Cs and -1.41% for Tl. Using these results we have performed analysis of the experimental data on atomic parity nonconservation. The obtained values of the nuclear weak charge, Q_W=-72.90(28)_{exp}(35)_{theor} for Cs, and Q_W=-116.7(1.2)_{exp}(3.4)_{theor} for Tl, agree with predictions of the standard model. As an application of our approach we have also calculated analytically dependence of the Lamb shift on the finite nuclear size.

hep-ph↗
arXiv2002

Low-energy electron scattering in a strong Coulomb field

The analytic expression for the cross section of low-energy electron scattering in a strong Coulomb field is obtained. It is shown that in a wide energy region this cross section differs essentially from that obtained in the first Born approximation.

physics.atom-ph↗