arXiv subjects

Konstantin V. Grigorishin

Publications and source records attributed to Konstantin V. Grigorishin.

12 recordsLinked to original sources

arXiv2026

Role of the equivalence principle in gauge and axial symmetries of Yukawa coupling, and the strong CP problem

It is demonstrated the fundamental role of the equivalence principle in gravity for the Yukawa coupling between scalar and fermion fields. The Kibble-Zurek mechanism for formation of topological defects as vortexes and monopoles breaks down in system with a global gauge symmetry only. At the same time, the different vacuums can occur, which are separated be domain walls. The equivalence principle makes the strong violation of CP invariance impossible. Thus the axion hypothesis becomes redundant.

hep-ph↗

arXiv2025

Three-band extension for the Glashow-Weinberg-Salam model

By analogy with the Ginzburg-Landau theory of multi-band superconductors with inner (interband) Josephson couplings we formulate the three-band Glashow-Weinberg-Salam model with weak Josephson couplings between strongly asymmetrical condensates of scalar (Higgs) fields. Unlike usual single-band model, we found three Higgs bosons corresponding to three generations of particles, moreover the heaviest of them corresponds to the already discovered H-boson and decays into fermions of only the third generation through Yukawa interaction. The other two decay into fermions of the first and second generations accordingly, but they are difficult to observe due to very poor conditions for production. We found two sterile ultra-light Leggett bosons, the Bose condensates of which form the dark halos of galaxies and their clusters (i.e so called "dark matter"). The masses of the Leggett bosons are determined by the coefficient of the interband coupling and can be arbitrarily small ($\sim 10^{-20}\mathrm{eV}$) due to non-perturbativeness of the interband coupling. Since propagation of Leggett bosons is not accompanied by current, these bosons are not absorbed by gauge fields unlike the common-mode Goldstone bosons. Three coupled condensates of the scalar fields are related to the existence of three generations of leptons, where each generation interacts with the corresponding condensate getting mass. The interflavour mixing between the generations of active neutrinos and sterile right-handed neutrinos in the three-band system causes the existence of mass states of neutrino without interaction with the Higgs condensates.

cond-mat.supr-con↗

arXiv2022

Collective excitations in two-band superconductors

We investigate the eigen oscillations of internal degrees of freedom (Higgs mode and Goldstone mode) of two-band superconductors using the extended time-dependent Ginzburg-Landau theory, formulated in a work Grigorishin (2021) \cite{grig2}, for the case of two coupled order parameters by both the internal proximity effect and the drag effect. It is demonstrated, that the Goldstone mode splits into two branches: common mode oscillations with the acoustic spectrum, which is absorbed by the gauge field, and anti-phase oscillations with the energy gap (mass) in the spectrum determined by the interband coupling, which can be associated with the Leggett mode. The Higgs mode splits into two branches also: a massive one, whose energy gap vanishes at the critical temperature $T_{c}$, another massive one, whose energy gap does not vanish at $T_{c}$. It is demonstrated, that the second branch of the Higgs mode is nonphysical, and it, together with the Leggett mode, can be removed by the special choice of coefficient at the "drag" term in the Lagrangian. In the same time, such a choice leaves only one coherence length, thereby prohibiting so-called type-1.5 superconductors. We analyze experimental data about the Josephson effect between two-band superconductors. In particular, it is demonstrated, that the resonant enhancement of the DC current through a Josephson junction at a resonant bias voltage $V_{\mathrm{res}}$, when the Josephson frequency matches the frequency of some internal oscillation mode in two-band superconductors (banks), can be explained with the coupling between AC Josephson current and Higgs oscillations. Thus, explanation of this effect does not need the Leggett mode.

cond-mat.supr-con↗

arXiv2021

Extended time-dependent Ginzburg-Landau theory

We formulate the gauge invariant Lorentz covariant Ginzburg-Landau theory which describes nonstationary regimes: relaxation of a superconducting system accompanied by eigen oscillations of internal degrees of freedom (Higgs mode and Goldstone mode), and also forced oscillations under the action of an external gauge field. The theory describes Lorentz covariant electrodynamics of superconductors where Anderson-Higgs mechanism occurs, at the same time the dynamics of conduction electrons remains non-relativistic. It is demonstrated that Goldstone oscillations cannot be accompanied by oscillations of charge density and they generate the transverse field only. In addition, we consider Goldstone modes and features of Anderson-Higgs mechanism in two-band superconductors. We study dissipative processes, which are caused by movement of the normal component of electron liquid and violate the Lorentz covariance, on the examples of the damped oscillations of the order parameter and the skin-effect for electromagnetic waves. An experimental consequence of the extended time-dependent Ginzburg-Landau theory regarding the penetration of the electromagnetic field into a superconductor is proposed.

cond-mat.supr-con↗

arXiv2020

Eliashberg theory with the external pair potential

Based on BCS model with the external pair potential formulated in a work Grigorishin (2017) [1], analogous model with electron-phonon coupling and Coulomb coupling is proposed. The generalized Eliashberg equations in the regime of renormalization of the order parameter are obtained. High temperature asymptotics and effect of Coulomb pseudopotential on them are investigated: as in the BCS model the order parameter asymptotically tends to zero as temperature rises, but the accounting of the Coulomb pseudopotential leads to existence of critical temperature. The effective Ginzburg-Landau theory is formulated for such model.

cond-mat.supr-con↗

arXiv2019

The role of electron-vibron interaction and local pairing in conductivity and superconductivity of alkali-doped fullerides

We investigate the competition between the electron-vibron interaction (interaction with the Jahn-Teller phonons) and the Coulomb repulsion in a system with the local pairing of electrons on the 3-fold degenerate lowest unoccupied molecular orbital (LUMO). The el.-vib. interaction and the local pairing radically change conductivity and magnetic properties of alkali-doped fullerides $\texttt{A}_{n}\texttt{C}_{60}$, which would have to be antiferromagnetic Mott insulators: we have shown that materials with $n=1,5$ and $\texttt{A}=\texttt{K},\texttt{Rb}$ are conductors but not superconductors; $n=3$ and $\texttt{A}=\texttt{K},\texttt{Rb}$ are conductors and superconductors at low temperatures, but with $\texttt{A}=\texttt{Cs}$ they are Mott-Jahn-Teller insulators at normal pressure; $n=2,4$ are nonmagnetic Mott insulators. Thus superconductivity, conductivity and insulation of these materials have common nature. Using this approach we obtain the phase diagram of $\texttt{A}_{3}\texttt{C}_{60}$ analytically, which is the result of interplay between the local pairing, the el.-vib. interaction, Coulomb correlations, and formation of small radius polarons.

cond-mat.supr-con↗

arXiv2018

BCS theory with the external pair potential

We consider a hypothetical substance, where interaction between (within) structural elements of condensed matter (molecules, nanoparticles, clusters, layers, wires etc.) depends on state of Cooper pairs: an additional work must be made against this interaction to break a pair. Such a system can be described by BCS Hamiltonian with the external pair potential term. In this model the potential essentially renormalizes the order parameter: if the pairing lowers energy of the structure the energy gap is slightly enlarged at zero temperature and asymptotically tends to zero as temperature rises. Thus the critical temperature of such a superconductor is equal to infinity formally. For this case the effective Ginzburg-Landau theory is formulated, where the coherence length decreases as temperature rises, the GL parameter and the second critical field are increasing functions of temperature unlike the standard theory. If the pairing enlarges energy of the structure then suppression of superconductivity and the first order phase transition occur.

cond-mat.supr-con↗

arXiv2017

The role of electron-vibron interaction and local pairing in conductivity and superconductivity of alkali-doped fullerides. The route to a room-temperature superconductor

We investigate the competition between the electron-vibron interaction (interaction with the Jahn-Teller phonons) and the Coulomb repulsion in a system with local pairing of electrons on the triply degenerate lowest unoccupied molecular orbital (LUMO). The electron-vibron interaction radically changes conductivity and magnetic properties of alkali-doped fullerides AnC60, which should be antiferromagnetic Mott insulators: we have found that materials with n=1,2 and A=K,Rb are conductors but not superconductors; n=3 and A=K,Rb are conductors (superconductors at low temperatures), but with A=Cs are Mott insulators at normal pressure; n=2,4 are nonmagnetic Mott insulators. We have shown that superconductivity, conductivity and insulation of these materials have common nature. Based on the alkali-doped fullerides we propose a hypothetical material with a significantly higher critical temperature using the model of superconductivity with the external pair potential formulated in a work K.V. Grigorishin Phys. Lett. A 381 3089 (2017).

cond-mat.supr-con↗

arXiv2017

The role of phase fluctuations in model of superconductivity with the external pair potential

We investigate the stability of the solutions of the BCS model with the external pair potential formulated in a work K.V. Grigorishin arXiv:1605.07080. It has been shown that the cause of superconductivity in this model is the electron-electron interaction only and the potential cannot impose superconductivity since the superconducting ordering will be destroyed by phase fluctuations in a form of quantum turbulence (vortexes, vortex rings, vortex tangles etc.). The external pair potential renormalizes the order parameter in initial superconducting matter and the bosonic scenario of transition to normal state in a clear 3D superconductor occurs unlike BCS theory where the fermionic scenario takes place.

cond-mat.supr-con↗

arXiv2016

Effective Ginzburg-Landau free energy functional for multi-band isotropic superconductors

It has been shown that interband mixing of gradients of two order parameters (drag effect) in an isotropic bulk two-band superconductor plays important role - such a quantity of the intergradients coupling exists that the two-band superconductor is characterized with a single coherence length and a single Ginzburg-Landau (GL) parameter. Other quantities or neglecting of the drag effect lead to existence of two coherence lengths and dynamical instability due to violation of the phase relations between the order parameters. Thus so-called type-1.5 superconductors are impossible. An approximate method for solving of set of GL equations for a multi-band superconductor has been developed: using the result about the drag effect it has been shown that the free-energy functional for a multi-band superconductor can be reduced to the GL functional for an effective single-band superconductor.

cond-mat.supr-con↗

arXiv2015

A superconductor in the external pair potential. Accounting of the Coulomb pseudopotential

Formulated in [Low Temperature Physics/Fizika Nizkikh Temperatur, 41, 482 (2015)] model of hypothetical superconductivity with the source term (external pair potential) in BCS hamiltonian is generalized for a case if electrons interacts via both BCS model attraction and screened Coulomb repulsion. Unlike the previous work the superconductor has critical temperature which determined with the Coulomb interaction within a Cooper pair. It has been shown the external pair potential is effective for superconductors where Tolmachev logarithm is small (nonadiabatic case). A free energy functional and equations similar to Ginzburg-Landau equations have been found for such a model.

cond-mat.supr-con↗

arXiv2015

Toy model of superconductivity

The model of hypothetical superconductivity, where the energy gap asymptotically approaches zero as temperature or magnetic field increases, has been proposed. Formally the critical temperature and the second critical field for such a superconductor is equal to infinity. Thus the material is in superconducting state always.

cond-mat.supr-con↗