arXiv subjects

A. Reshetnyak

Publications and source records attributed to A. Reshetnyak.

10 recordsLinked to original sources

arXiv2025

Towards Lagrangian dynamics for constrained mixed-symmetric interacting higher-spin fields

The necessary and sufficient conditions to construct consistent Lagrangian formulation for irreducible interacting massless higher-spin (HS) fields on $d$-dimensional Minkowski space within approach with incomplete BRST operator and off-shell holonomic constraints are found. It is shown that in addition to superconmmuting of incomplete BRST operator with appropriate traceless and Young constraints, which annihilate the field and gauge parameter vectors, these constraints should form Abelian superalgebra both with BRST operator and with operators of cubic, quartic and etc. vertices. The consistent deformation of free model with constrained HS fields with integer spin requires for the cubic vertex to be by BRST-closed, traceless and Young-symmetric solution of the generating equations. The explicit form for the vertices for irreducible constrained interacting fields are obtained by means of projectors on traceless and Young-symmetric modes.

hep-th↗

arXiv2023

Gauge Invariant Lagrangian Formulations for Mixed Symmetry Higher Spin Bosonic Fields in AdS Spaces

We deduce a non-linear commutator higher-spin (HS) symmetry algebra which encodes unitary irreducible representations of the AdS group -- subject to a Young tableaux $Y(s_1,\ldots ,s_k)$ with $k\geq 2$ rows -- in a $d$-dimensional anti-de-Sitter space. Auxiliary representations for a deformed non-linear HS symmetry algebra in terms of a generalized Verma module, as applied to additively convert a subsystem of second-class constraints in the HS symmetry algebra into one with first-class constraints, are found explicitly in the case of a $k=2$ Young tableaux. An oscillator realization over the Heisenberg algebra for the Verma module is constructed. The results generalize the method of constructing auxiliary representations for the symplectic $sp(2k)$ algebra used for mixed-symmetry HS fields in flat spaces \cite{BRbos}. Polynomial deformations of the $su(1,1)$ algebra related to the Bethe ansatz are studied as a by-product. A nilpotent BRST operator for a non-linear HS symmetry algebra of the converted constraints for $Y(s_1, s_2)$ is found, with non-vanishing terms (resolving the Jacobi identities) of third order in powers of ghost coordinates. A gauge-invariant unconstrained reducible Lagrangian formulation for a free bosonic HS field of generalized spin $(s_1,s_2)$ is deduced. Following the results of \cite{BuchbinderReshetnyak, BRmasscub}, we develop a BRST approach to constructing general off-shell local cubic interaction vertices for irreducible massive higher-spin fields (being candidates for massive particles in the Dark Matter problem). A new reducible gauge-invariant Lagrangian formulation for an antisymmetric massive tensor field of spin $(1,1)$ is obtained.

hep-th↗

arXiv2020

BRST-BFV and BRST-BV Descriptions for Bosonic Fields with Continuous Spin on $R^{1,d-1}$

Gauge-invariant descriptions for a free bosonic scalar field of continuous spin in a $d$-dimensional Minkowski space-time using a metric-like formulation are constructed on the basis of a constrained BRST-BFV approach we propose. The resulting BRST-BFV equations of motion for a scalar field augmented by ghost operators contains different sets of auxiliary fields, depending on the manner of a partial gauge-fixing and a resolution of some of the equations of motion for a BRST-unfolded first-stage reducible gauge theory. To achieve an equivalence of the resulting BRST-unfolded constrained equations of motion with the initial irreducible Poincare group conditions of a Bargmann--Wigner type, it is demonstrated that one should replace the field in these conditions by a class of gauge-equivalent configurations. Triplet-like, doublet-like constrained descriptions, as well as an unconstrained quartet-like non-Lagrangian and Lagrangian formulations, are derived using both Fronsdal-like and new tensor fields. In particular, the BRST--BV equations of motion and Lagrangian using an appropriate set of Lagrangian multipliers in the minimal sector of the respective field and antifield configurations are constructed in a manifest way.

hep-th↗

arXiv2018

On the vibron nature in the system of two parallel macromolecular chains: the influence of interchain coupling

We studied the properties of the intramolecular vibrational excitation (vibron) at finite temperature in a system which consists of two parallel macromolecular chains. It was assumed that vibron interacts exclusively with dispersionless optical phonons and the whole system is considered to be in thermal equilibrium. Particular attention has been paid to the examination of the impact of the temperature and strength of the interchain coupling on the \emph{small polaron} crossover. For that purpose we employed partial dressing method which enables the study of the degree of the phonon dressing of the vibron excitations in a wide area of system parameter space. We found that in the non--adiabatic regime the degree of dressing as a function of coupling constant continuously increases reflecting the smooth transition of the slightly dressed, practically free vibron, to a heavily dressed one: small polaron. As "adiabaticity" rises this transition becomes increasingly steeper, and finally, in the adiabatic limit, a discontinuous "jump" of the degree of dressing is observed. The interchain coupling manifests itself through the increase of the effective adiabatic parameter of the system.

cond-mat.mes-hall↗

arXiv2018

On the vibron-polaron damping in quasi 1D macromolecular chains

The properties of the intramolecular vibrational excitation (vibron) in a quasi 1D macromolecular structure are studied. It is supposed that due to the vibron interaction with optical phonon modes, a vibron might form partially dressed small polaron states. The properties of these states are investigated in dependence on the basic system parameters and temperature of a thermal bath. We also investigate the process of damping of the polaron amplitude as a function of temperature and vibron-phonon coupling strength. Two different regimes of the polaron damping are found and discussed.

cond-mat.mes-hall↗

arXiv2015

The influence of interchain coupling on intramolecular oscillation mobility in coupled macromolecular chains: the case of coplanar parallel chains

We enlarge our results from the study of the hopping mechanism of the oscillation excitation transport in 1D model of one biology-like macromolecular chain to the case of a system composed from two 1D parallel macromolecular chains with consideration of the properties of intramolecular oscillation excitations. We suppose, that due to the exciton interaction with thermal oscillation (generated by mechanical phonon subsystem) of structural elements (consisting of the peptide group) of the chains, the exciton becomes by self trapped and forms the polaron state. We suggest a model which generalizes the modified Holstein polaron model to the case of two macromolecular chains and find that because of the interchain coupling, the exciton energy band is splitted into two subbands. The hopping process of exciton migration along the macromolecular chains is studied in dependence of system parameters and temperature. We pay an special attention to the temperature range (near T=300 K) in which living cells operate. It is found that for the certain values of the system parameters there exists the abrupt change of the exciton migration nature from practically free (light) exciton motion to an immobile (heavy, dressed by phonon cloud) quasiparticle We discuss an application of the obtained results to the exciton transport both within deoxyribonucleic acid molecule and in the 2D polymer films organized from such macromolecular chains.

cond-mat.mes-hall↗

arXiv2014

Vibron transport in macromolecular chains

We study the hopping mechanism of the vibron excitation transport in the simple 1D model of biological macromolecular chains. We supposed that the vibron interaction with thermal oscillations of the macromolecular structural elements will result in vibron self -trapping, and the formation of the partial dressed vibron state. With use of the modified Holstein polaron model, we calculate vibron diffusivity in dependence of the basic system parameters and temperature. We obtain that the vibron diffusivity smoothly decreases in non adiabatic limit when the strength of the vibron-phonon coupling grows. However this dependence becomes by discontinuous one in case of growth of the adiabaticity of the system. The value of the critical point depends of the system temperature, and at room temperatures it belongs to the low or intermediate coupling regime. We discuss an application of these results to study of vibron transport to 3D bundles of such macromolecules chains considering it as polymer nanorods and to 2D polymer films organized from such macromolecules.

cond-mat.mes-hall↗

arXiv2012

Vibron Self--trapped States in Biological Macromolecules: Comparison of Different Theoretical Approaches

A study of the applicability of the variational treatments based on using of the modified Lang-Firsov unitary transformation (MLF method) in the investigation of the vibron self-trapped states in biological macromolecular chains are presented. We compare the values of the ground state energy predicted by MLF methods with the values of the ground state energy predicted by the standard small-polaron theory, for various values of the basic energy parameters of the system. We obtain regions in system parameter space where MLF approach gives better description of the vibron states.

cond-mat.mes-hall↗

arXiv2011

General Lagrangian Formulation for Higher Spin Fields with Arbitrary Index Symmetry. I. Bosonic fields

We construct a Lagrangian description of irreducible integer higher-spin representations of the Poincare group with an arbitrary Young tableaux having k rows, on a basis of the universal BRST approach. Starting with a description of bosonic mixed-symmetry higher-spin fields in a flat space of any dimension in terms of an auxiliary Fock space associated with special Poincare module, we realize a conversion of the initial operator constraint system (constructed with respect to the relations extracting irreducible Poincare-group representations) into a first-class constraint system. For this purpose, we find, for the first time, auxiliary representations of the constraint subalgebra, to be isomorphic due to Howe duality to sp(2k) algebra, and containing the subsystem of second-class constraints in terms of new oscillator variables. We propose a universal procedure of constructing unconstrained gauge-invariant Lagrangians with reducible gauge symmetries describing the dynamics of both massless and massive bosonic fields of any spin. It is shown that the space of BRST cohomologies with a vanishing ghost number is determined only by the constraints corresponding to an irreducible Poincare-group representation. As examples of the general procedure, we formulate the method of Lagrangian construction for bosonic fields subject to arbitrary Young tableaux having 3 rows and derive the gauge-invariant Lagrangian for new model of massless rank-4 tensor field with spin $(2,1,1)$ and second-stage reducible gauge symmetries.

hep-th↗

arXiv2010

Anomalous thermal conductivity in multiwalled carbon nanotubes with impurities and short-range order

Low-temperature thermal conductivity and thermopower of multiwalled carbon nanotubes considered within a bundle of nanotubes are calculated taking into account multiple scattering of electrons on the atoms of impurities (like single carbon atoms) and short-range order regions arising due to a some distribution of the impurities. The calculations are realized on a base of the temperature diagrammatic Feynman techniques and the results of our research are in a good quantitative and qualitative agreement with the corresponding experimental data for multiwalled carbon nanotubes with diameter less or equal 10 nm at T<50K.

hep-th↗