arXiv subjects

A. Khvedelidze

Publications and source records attributed to A. Khvedelidze.

8 recordsLinked to original sources

arXiv2020

COMET Phase-I Technical Design Report

The Technical Design for the COMET Phase-I experiment is presented in this paper. COMET is an experiment at J-PARC, Japan, which will search for neutrinoless conversion of muons into electrons in the field of an aluminium nucleus ($μ-e$ conversion, $μ^- N \to e^- N$); a lepton flavor violating process. The experimental sensitivity goal for this process in the Phase-I experiment is $3.1\times10^{-15}$, or 90 % upper limit of branching ratio of $7\times 10^{-15}$, which is a factor of 100 improvement over the existing limit. The expected number of background events is 0.032. To achieve the target sensitivity and background level, the 3.2 kW 8 GeV proton beam from J-PARC will be used. Two types of detectors, CyDet and StrECAL, will be used for detecting the \mue conversion events, and for measuring the beam-related background events in view of the Phase-II experiment, respectively. Results from simulation on signal and background estimations are also described.

physics.ins-det↗

arXiv2020

On measures of classicality/quantumness in quasiprobability representations of finite-dimensional quantum systems

In the present report we discuss measures of classicality/quantumness of states of finite-dimensional quantum systems, which are based on a deviation of quasiprobability distributions from true statistical distributions. Particularly, the dependence of the global indicator of classicality on the assigned geometry of a quantum state space is analysed for a whole family of Wigner quasiprobability representations. General considerations are exemplified by constructing the global indicator of classicality/quantumness for the Hilbert-Schmidt, Bures and Bogoliubov-Kubo-Mori ensembles of qubits and qutrits.

quant-ph↗

arXiv2016

On the ring of local unitary invariants for mixed X-states of two qubits

Entangling properties of a mixed 2-qubit system can be described by the local homogeneous unitary invariant polynomials in elements of the density matrix. The structure of the corresponding invariant polynomial ring for the special subclass of states, the so-called mixed X-states, is established. It is shown that for the X-states there is an injective ring homomorphism of the quotient ring of SU(2)xSU(2) invariant polynomials modulo its syzygy ideal and the SO(2)xSO(2)-invariant ring freely generated by five homogeneous polynomials of degrees 1,1,1,2,2.

quant-ph↗

arXiv2013

Entanglement of spins under a strong laser influence

The fate of entanglement of spins for two heavy constituents of a bound state moving in a strong laser field is analyzed within the semiclassical approach. The bound state motion as a whole is considered classically beyond the dipole approximation and taking into account the magnetic field effect by using the exact solution to the Newton equation. At the same time the evolution of constituent spins under the laser influence is studied quantum mechanically. The spin density matrix is determined as solution to the von Neumann equation with the effective Hamiltonian, describing spin-laser interaction along the bound state classical trajectory. Based on the solution, the dynamics of concurrence of spins is calculated for the maximally entangled Werner states as well as for an initially uncorrelated state.

quant-ph↗

arXiv2006

Towards an algorithmisation of the Dirac constraint formalism

Central issues of the Dirac constraint formalism are discussed in relation to the algorithmic methods of commutative algebra based on the Groebner basis techniques. For a wide class of finite dimensional polynomial degenerate Lagrangian systems, we describe an algorithmic scheme of computation of the complete set of constraints, their separation into subsets of first and second class constraints as well as the construction of a generator of local symmetry transformations. The proposed scheme is exemplified by considering the so-called light-cone Yang-Mills mechanics with an SU(2) gauge structure group.

math-ph↗

arXiv2005

On the Hamiltonian reduction of geodesic motion on SU(3) to SU(3)/SU(2)

The reduced Hamiltonian system on T*SU(3)/SU(2)) is derived from a Riemannian geodesic motion on the SU(3) group manifold parameterised by the generalised Euler angles and endowed with a bi-invariant metric. Our calculations show that the metric defined by the derived reduced Hamiltonian flow on the orbit space SU(3)/SU(2)=S^5 is not isometric or even geodesically equivalent to the standard Riemannian metric on the five-sphere S^5 embedded into R^6.

hep-th↗

arXiv1994

Zero Modes of Gauss' Constraint in Gaugeless Reduction of Yang - Mills Theory

The physical variables for pure Yang - Mills theory in four - dimensional Minkowskian space time are constructed without using a gauge fixing condition} by the explicit resolving of the non - Abelian Gauss constraint and by the Bogoliubov transformation that diagonalizes the kinetic term in reduced action (action on constraint shell). As a result, the reduced action is expressed in terms of gauge invariant field variables including an additional global (only time - dependent) one, describing zero mode dynamics of the Gauss constraint. This additional variable reflects the symmetry group of topologically nontrivial transformations remaining after the reduction. ( It gives also the characteristic of the Gribov ambiguity from the point of view of the gauge fixing method.) The perturbation theory in terms of quasiparticles with the new stable vacuum, which is defined through the zero mode configuration, is proposed. It is shown, that the averaging of Green's functions for quasiparticles over the global variable leads to the mechanism of color confinement.

hep-th↗

arXiv1994

Zero Modes of First Class Secondary Constraints in Gauge Theories

Zero modes of first class secondary constraints in the two-dimensional electrodynamics and the four-dimensional SU(2) Yang-Mills theory are considered by the method of reduced phase space quantization in the context of the problem of a stable vacuum. We compare the description of these modes in the Dirac extended method and reveal their connection with the topological structure of the gauge symmetry group. Within the framework of the "reduced" quantization we construct a new global realization of the homotopy group representation in the Yang-Mills theory, where the role of the stable vacuum with a finite action plays the Prasad-Sommerfield solution.

hep-th↗