arXiv subjects

Nikolay Sh. Izmailian

Publications and source records attributed to Nikolay Sh. Izmailian.

4 recordsLinked to original sources

arXiv2023

Exact coefficients of finite-size corrections in the Ising model with Brascamp-Kunz boundary conditions and their relationships for strip and cylindrical geometries

We derive exact finite-size corrections for the free energy $F$ of the Ising model on the ${\cal M} \times 2 {\cal N}$ square lattice with Brascamp-Kunz boundary conditions. We calculate ratios $r_p(ρ)$ of $p$th coefficients of F for the infinitely long cylinder (${\cal M} \to \infty$) and the infinitely long Brascamp-Kunz strip (${\cal N} \to \infty$) at varying values of the aspect ratio $ρ={(\cal M}+1) / 2{\cal N}$. Like previous studies have shown for the two-dimensional dimer model, the limiting values $p \to \infty$ of $r_p(ρ)$ exhibit abrupt anomalous behaviour at certain values of $ρ$. These critical values of $ρ$ and the limiting values of the finite-size-expansion-coefficient ratios differ, however, between the two models.

cond-mat.stat-mech↗

arXiv2019

Exact finite-size corrections in the dimer model on a planar square lattice

We consider the dimer model on the rectangular $2M \times 2N$ lattice with free boundary conditions. We derive exact expressions for the coefficients in the asymptotic expansion of the free energy in terms of the elliptic theta functions ($θ_2, θ_3, θ_4$) and the elliptic integral of second kind ($E$), up to 22nd order. Surprisingly we find that ratio of the coefficients $f_p$ in the free energy expansion for strip ($f_p^\mathrm{strip}$) and square ($f_p^\mathrm{sq}$) geometries $r_p={f_p^\mathrm{strip}}/{f_p^\mathrm{sq}}$ in the limit of large $p$ tends to $1/2$. Furthermore, we predict that the ratio of the coefficients $f_p$ in the free energy expansion for rectangular ($f_p(ρ)$) for aspect ratio $ρ> 1$ to the coefficients of the free energy for square geometries, multiplied by $ρ^{-p-1}$, that is $r_p=ρ^{-p-1} {f_p(ρ)}/{f_p^\mathrm{sq}}$, is also equal to $1/2$ in the limit of $p \to \infty$. We find that the corner contribution to the free energy for the dimer model on rectangular $2M \times 2N$ lattices with free boundary conditions is equal to zero and explain that result in the framework of conformal field theory, in which the central charge of the considering model is $c=-2$. We also derive a simple exact expression for the free energy of open strips of arbitrary width.

cond-mat.stat-mech↗

arXiv2017

Threshold behavior of free electron lasers without inversion

The interaction between noncolinear laser and relativistic electron beams in static magnetic undulator has been studied within the framework of dispersion equations. For a free-electron laser without inversion (FELWI), the threshold parameters are found. The large-amplification regime should be used to bring an FELWI above the threshold laser power.

physics.acc-ph↗

arXiv2017

Electrons for Detection of Casimir Photons

We propose a method for the detection of a dynamical Casimir effect. Assuming that the Casimir photons are being generated in an electromagnetic cavity with a vibrating wall (dynamical Casimir effect), we consider electrons passing through the cavity to be interacting with the intracavity field. We show that the dynamical Casimir effect can be observed via the measurement of the change in the average or in the variance of the electron kinetic energy. We point out that the enhancement of the effect due to finite temperatures makes it easier to detect the Casimir photons.

quant-ph↗