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O. F. Dayi

Publications and source records attributed to O. F. Dayi.

At least 19 recordsLinked to original sources
arXiv2020

Semiclassical transport equations of Dirac particles in rotating frames

We establish covariant semiclassical transport equations of massive spin-1/2 particles which are generated by the quantum kinetic equation modified by enthalpy current dependent terms. The purpose of modification is to take into account the noninertial properties due to the angular velocity of rotating frame which is equivalent to the fluid vorticity in hydrodynamical approach. We present the equations satisfied by the Wigner function components and by studying their solution in the semiclassical approximation we accomplish the transport equations. To acquire a three-dimensional kinetic theory, the relativistic kinetic equations in the comoving frame are integrated over the zeroth component of four-momentum. The resulting vector and axial-vector currents are calculated at zero temperature. There exists another three-dimensional formulation of Dirac particles which correctly addresses the noninertial features of rotating coordinates. We review it briefly and obtain the mass corrections to the chiral vector and axial-vector currents produced by this formulation.

hep-th↗
arXiv2019

Some Features of Semiclassical Chiral Transport in Rotating Frames

Semiclassical chiral kinetic theories in the presence of electromagnetic fields as well as vorticity can be constructed by means of some different relativistic or nonrelativistic approaches. To cover the noninertial features of rotating frames one can start from the modified quantum kinetic equation of Wigner function in Minkowski spacetime. It provides a relativistic chiral transport equation whose nonrelativistic limit yields a consistent three-dimensional kinetic theory which does not depend explicitly on spatial coordinates. Recently a chiral transport equation in curved spacetime has been proposed and its nonrelativistic limit in rotating coordinates was considered in the absence of electromagnetic fields. We show that the modified theory can be extended to curved spacetime. The related particle current density and chiral transport equation for an inertial observer in the rotating frame are derived. A novel three-dimensional chiral kinetic transport equation is established by inspecting the nonrelativistic limit of the curved spacetime approach in the rotating frame for a comoving observer in the presence of electromagnetic fields. It explicitly depends on spatial coordinates. We prove that it is consistent with the chiral anomaly, chiral magnetic and vortical effects.

hep-th↗
arXiv2018

Spin Currents of Charged Dirac Particles in Rotating Coordinates

The semiclassical Boltzmann transport equation of charged, massive fermions in a rotating frame of reference, in the presence of external electromagnetic fields is solved in the relaxation time approach to establish the distribution function up to linear order in the electric field in rotating coordinates, centrifugal force and the derivatives. The spin and spin current densities are calculated by means of this distribution function at zero temperature up to the first order. It is shown that the nonequilibrium part of the distribution function yields the spin Hall effect for fermions constrained to move in a plane perpendicular to the angular velocity and magnetic field. Moreover it yields an analogue of Ohm's law for spin currents whose resistivity depends on the external magnetic field and the angular velocity of the rotating frame. Spin current densities in three-dimensional systems are also established.

math-ph↗
arXiv2017

Semiclassical dynamics of Dirac and Weyl particles in rotating coordinates

The semiclassical kinetic theory of Dirac particles in the presence of external electromagnetic fields and global rotation is established. To provide the Hamiltonian formulation of Dirac particles a symplectic two-form which is a matrix in spin indices is proposed. The particle number and current densities for the Dirac particles are acquired in the helicity basis. Following a similar procedure, semiclassical kinetic theory of the Weyl particles is accomplished. It is shown that the phase-space dynamics of the Weyl and Dirac particles is directly linked. The anomalous chiral effects due to the external electromagnetic fields and angular velocity of the frame are calculated.

hep-th↗
arXiv2015

A Semiclassical Kinetic Theory of Dirac Particles and Thomas Precession

Kinetic theory of Dirac fermions is studied within the matrix valued differential forms method. It is based on the symplectic form derived by employing the semiclassical wave packet build of the positive energy solutions of the Dirac equation. A satisfactory definition of the distribution matrix elements imposes to work in the basis where the helicity is diagonal which is also needed to attain the massless limit. We show that the kinematic Thomas precession correction can be studied straightforwardly within this approach. It contributes on an equal footing with the Berry gauge fields. In fact in equations of motion it eliminates the terms arising from the Berry gauge fields.

hep-th↗
arXiv2013

3+1 dimensional topological field theory as the effective action of neutral fermions

We proposed an action of neutral fermions interacting with external electromagnetic fields to construct a 3+1 dimensional topological field theory as the effective action attained by integrating out the fermionic fields in the related path integral. These neutral quasiparticles are assumed to emerge from the collective behavior of the original physical particles and holes (antiparticles). Although our construction is general it is particularly useful to formulate effective actions of the time reversal invariant topological insulators.

math-ph↗
arXiv2012

Effective field theory of topological insulator and the Foldy-Wouthuysen transformation

Employing the Foldy-Wouthuysen transformation it is demonstrated straightforwardly that the first and second Chern numbers are equal to the coefficients of the 2+1 and 4+1 dimensional Chern-Simons actions which are generated by the massive Dirac fermions coupled to the Abelian gauge fields. A topological insulator model in 2+1 dimensions is discussed and by means of a dimensional reduction approach the 1+1 dimensional descendant of the 2+1 dimensional Chern-Simons theory is presented. Field strength of the Berry gauge field corresponding to the 4+1 dimensional Dirac theory is explicitly derived through the Foldy-Wouthuysen transformation. Acquainted with it the second Chern numbers are calculated for specific choices of the integration domain. A method is proposed to obtain 3+1 and 2+1 dimensional descendants of the effective field theory of the 4+1 dimensional time reversal invariant topological insulator theory. Inspired by the spin Hall effect in graphene, a hypothetical model of the time reversal invariant spin Hall insulator in 3+1 dimensions is proposed.

math-ph↗
arXiv2011

Gauge Potential Formulations of the Spin Hall Effect in Graphene

Two different gauge potential methods are engaged to calculate explicitly the spin Hall conductivity in graphene. The graphene Hamiltonian with spin-orbit interaction is expressed in terms of kinematic momenta by introducing a gauge potential. A formulation of the spin Hall conductivity is established by requiring that the time evolution of this kinematic momentum vector vanishes. We then calculated the conductivity employing the Berry gauge fields. We show that both of the gauge fields can be deduced from the pure gauge field arising from the Foldy-Wouthuysen transformations.

math-ph↗
arXiv2009

Spin Hall Effect in Noncommutative Coordinates

A semiclassical constrained Hamiltonian system which was established to study dynamical systems of matrix valued non-Abelian gauge fields is employed to formulate spin Hall effect in noncommuting coordinates at the first order in the constant noncommutativity parameter theta . The method is first illustrated by studying the Hall effect on the noncommutative plane in a gauge independent fashion. Then, the Drude model type and the Hall effect type formulations of spin Hall effect are considered in noncommuting coordinates and θdeformed spin Hall conductivities which they provide are acquired. It is shown that by adjusting θdifferent formulations of spin Hall conductivity are accomplished. Hence, the noncommutative theory can be envisaged as an effective theory which unifies different approaches to similar physical phenomena.

hep-th↗
arXiv2007

N=1/2 Supersymmetric gauge theory in noncommutative space

A formulation of (non-anticommutative) N=1/2 supersymmetric U(N) gauge theory in noncommutative space is studied. We show that at one loop UV/IR mixing occurs. A generalization of Seiberg-Witten map to noncommutative and non-anticommutative superspace is employed to obtain an action in terms of commuting fields at first order in the noncommutativity parameter tetha. This leads to abelian and non-abelian gauge theories whose supersymmetry transformations are local and non-local, respectively.

hep-th↗
arXiv2007

Superfield formulation of N=4 supersymmetric Yang-Mills theory in extended superspace

Action of 4 dimensional N=4 supersymmetric Yang-Mills theory is written by employing the superfields in N=4 superspace which were used to prove the equivalence of its constraint equations and equations of motion. Integral forms of the extended superspace are engaged to collect all of the superfields in one "master" superfield. The proposed N=4 supersymmetric Yang-Mills action in extended superspace is shown to acquire a simple form in terms of the master superfield.

hep-th↗
arXiv2005

Duality invariance of non-anticommutative N=1/2 supersymmetric U(1) gauge theory

A parent action is introduced to formulate (S-) dual of non-anticommutative N=1\2 supersymmetric U(1) gauge theory. Partition function for parent action in phase space is utilized to establish the equivalence of partition functions of the theories which this parent action produces. Thus, duality invariance of non-anticommutative N=1\2 supersymmetric U(1) gauge theory follows. The results which we obtained are valid at tree level or equivalently at the first order in the nonanticommutativity parameter C_{μν}.

hep-th↗
arXiv2004

Equivalence of partition functions for noncommutative U(1) gauge theory and its dual in phase space

Equivalence of partition functions for U(1) gauge theory and its dual in appropriate phase spaces is established in terms of constrained hamiltonian formalism of their parent action. Relations between the electric--magnetic duality transformation and the (S) duality transformation which inverts the strong coupling domains to the weak coupling domains of noncommutative U(1) gauge theory are discussed in terms of the lagrangian and the hamiltonian densities. The approach presented for the commutative case is utilized to demonstrate that noncommutative U(1) gauge theory and its dual possess the same partition function in their phase spaces at the first order in the noncommutativity parameter θ.

hep-th↗
arXiv2003

Duals of noncommutative supersymmetric U(1) gauge theory

Parent actions for component fields are utilized to derive the dual of supersymmetric U(1) gauge theory in 4 dimensions. Generalization of the Seiberg-Witten map to the component fields of noncommutative supersymmetric U(1) gauge theory is analyzed. Through this transformation we proposed parent actions for noncommutative supersymmetric U(1) gauge theory as generalization of the ordinary case.Duals of noncommutative supersymmetric U(1) gauge theory are obtained. Duality symmetry under the interchange of fields with duals accompanied by the replacement of the noncommutativity parameter Θ_{μν} with \tildeΘ_{μν} = ε_{μνρσ}Θ^{ρσ} of the non--supersymmetric case is broken at the level of actions. We proposed a noncommutative parent action for the component fields which generates actions possessing this duality symmetry.

hep-th↗
arXiv2003

Noncommutative Maxwell-Chern-Simons theory, duality and a new noncommutative Chern-Simons theory in d=3

Noncommutative Maxwell-Chern-Simons theory in 3-dimensions is defined in terms of star product and noncommutative fields. Seiberg-Witten map is employed to write it in terms of ordinary fields. A parent action is introduced and the dual action is derived. For spatial noncommutativity it is studied up to second order in the noncommutativity parameter θ. A new noncommutative Chern-Simons action is defined in terms of ordinary fields, inspired by the dual action. Moreover, a transformation between noncommuting and ordinary fields is proposed.

hep-th↗
arXiv2002

Hamiltonian formulation of Noncommutative D3--Brane

Lagrangians of the Abelian Gauge Theory and its dual are related in terms of a shifted action. We show that in d=4 constrained Hamiltonian formulation of the shifted action yields Hamiltonian description of the dual theory, without referring to its Lagrangian. We apply this method, at the first order in the noncommutativity parameter theta, to the noncommutative U(1) gauge theory possessing spatial noncommutativity. Its dual theory is effectively a space--time noncommutative U(1) gauge theory. However, we obtain a Hamiltonian formulation where time is commuting. Space-time noncommutative D3--brane worldvolume Hamiltonian is derived as the dual of space noncommutative U(1) gauge theory. We show that a BPS like bound can be obtained and it is saturated for configurations which are the same with the ordinary D3-brane BIon and dyon solutions.

hep-th↗
arXiv2002

Wigner Functions for the Landau Problem in Noncommutative Spaces

An electron moving on plane in a uniform magnetic field orthogonal to plane is known as the Landau problem. Wigner functions for the Landau problem when the plane is noncommutative are found employing solutions of the Schroedinger equation as well as solving the ordinary *-genvalue equation in terms of an effective Hamiltonian. Then, we let momenta and coordinates of the phase space be noncommutative and introduce a generalized *-genvalue equation. We solve this equation to find the related Wigner functions and show that under an appropriate choice of noncommutativity relations they are independent of noncommutativity parameter.

hep-th↗