arXiv subjects

Anisur Rahaman

Publications and source records attributed to Anisur Rahaman.

At least 37 records · Page 2Linked to original sources

arXiv2022

Kerr-Sen-like Lorentz violating black holes and Superradiance phenomena

A Kerr-Sen-like black hole solution results from Einstein-bumblebee gravity. It contains a Lorentz violating (LV) parameter that enters when the bumblebee field receives vacuum expectation value through a spontaneously breaking of the symmetry of the classical action. The geometrical structure concerning the singularity of this spacetime is studied with reference to the parameters involved in the Kerr-Sen-like metric. We introduce this Einstein-bumblebee modified gravity to probe the role of spontaneous Lorentz violation on the superradiance scattering phenomena and the instability associated with it. We observe that for the low-frequency range of the scalar wave the superradiance scattering gets enhanced when the Lorentz-violating parameter $\ell$ takes the negative values and it reduces when values of $\ell$ are positive. The study of the black hole bomb issue reveals that for the negative values of $\ell$, the parameter space of the scalar field instability increase prominently, however, for its positive values, it shows a considerable reduction. We also tried to put constraints on the parameters contained in the Kerr-Sen-like black hole by comparing the deformation of the shadow produced by the black hole parameters with the observed deviation from circularity and the angular deviation from the $M87*$ data.

gr-qc↗

arXiv2022

Study of Einstein-bumblebee gravity with Kerr-Sen-like solution in the presence of a dispersive medium

A Kerr-Sen-like black hole solution appears in the Einstein-bumblebee theory of gravity. The solution contains contains a Lorentz violating parameter in an explicit manner. We study the null geodesics in the background of this Kerr-Sen-like black hole surrounded by a dispersive medium like plasma. We investigate the effect of the charge of the black hole, the Lorentz violation parameter, and the plasma parameter on the photon orbits with the evaluation of the effective potential in the presence of both the Lorentz violation parameter and the plasma parameter. We also study the influence of the Lorentz violation parameter and plasma parameter on the emission of energy from the black hole due to thermal radiation. Besides, we compute the angle of deflection of massless particles with weak-field approximation in this generalized situation and examine how it varies with the Lorentz violation parameter in presence of plasma. Constraining the parameters of this Lorentz violating Kerr-Sen-like black hole is also attempted here with the result obtained from the observations of the Event Horizon Telescope (EHT) collaboration.

gr-qc↗

arXiv2021

On the indistinguishability of Chiral QED with parameter-free Faddeevian anomaly and QED under a chiral constraint

We carry out an investigation imposing a chiral constraint in the phase space of vector and axial-vector Schwinger model. We find that resulting model is identical to gauge non-invariant model which was obtained by the imposition of chiral constraint in the phase-space of in Chiral Schwinger model with the parameter-free Faddeevian anomaly. Three different models having different types of interaction between the matter and gauge field become indistinguishable under a chiral constraint at the quantum mechanical level. The resulting gauge non-invariant model has an equivalent gauge-invariant version in the same phase space that can be identified with the vector Schwinger model.

hep-th↗

arXiv2021

Minimal length, maximal momentum and stochastic gravitational waves spectrum generated from cosmological QCD phase transition

We investigate thoroughly the temporal evolution of the universe temperature as a function of the Hubble parameter associated with the Stochastic Gravitational Wave (SGW), that formed at the cosmological QCD phase transition epoch to the current epoch, within the Generalized Uncertainty Principle (GUP) framework. Here we use GUP version which provide constraints on the minimum measurable length and the maximum observable momentum, that characterized by a free parameter $α$. We study the effect of this parameter on the SGW background. We show that the effect can slightly enhance the SGW frequency in the lower frequency regime which might be important in the detection of SGW in the future GW detection facilities.

gr-qc↗

arXiv2020

Bumblebee gravity and particle motion in Snyder noncommutative spacetime structures

A metric with a Lorentz violating parameter is associated with the bumblebee gravity model. We study the motion of a particle in this bumblebee background where the dynamical variables satisfy non-canonical Snyder algebra along with some critical survey on the classical observations in the bumblebee background to see how these would likely differ from Schwarzschild background. It has been found that the perihelion shift acquires a generalized expression with two independent parameters. One of these two is connected with the Lorentz violating factor and the other is involved in the Snyder algebraic formulation. We also observe that the time period of revolution, in general, acquires a Lorentz violating factor in the bumblebee background, however, for the circular orbit, it remains unchanged even in the presence of the Lorentz violating factor in the bumblebee background. The parameters used here can be constrained with the same type of conjecture used earlier.

hep-th↗

arXiv2020

Bumblebee gravity with a Kerr-Sen-like solution and its Shadow

Lorentz-Violating (LV) scenario gets involved through a bumblebee field vector field $B_μ$. A spontaneous symmetry breaking allows the field to acquires a vacuum expectation value that generates LV into the system. A Kerr-Sen-like solution has been found out starting from the generalized form of a radiating stationery axially symmetric black-hole metric. We compute the effective potential offered by the null geodesics in the bumblebee rotating black-hole spacetime. The shadow has been sketched for different variations of the parameters involved in the system. A careful investigation has been carried out to study how the shadow gets affected when Lorentz violation enters into the picture. The emission rate of radiation has also been studied and how it varies with the LV parameter $\ell$ is studied scrupulously.

gr-qc↗

arXiv2020

Quantization of gauged Floreanini-Jackiw chiral boson with Faddeevian anomaly

We consider the gauged model of Siegel type chiral boson with a Lorentz non-covariant mass-like term for the gauge fields which is found to be equivalent to the chiral Schwinger model with Faddeevian anomaly when it is described in terms of Floreanini-Jackiw type chiral boson. We carry out the quantization of gauge non-invariant version this model in both the Lagrangian and Hamiltonian formulation. The quantization of the gauge-invariant version of this model in the extended phase space also has been carried out in the Lagrangian formulation. The gauge-invariant version of this model in the extended phase space is found to map onto the physical phase space with the appropriate gauge fixing condition. BRST symmetry associated with this model has been studied with different gauge fixing terms. It has been shown that the same model shows off-shell as well as on-shell BRST invariance depending on the choice of gauge fixing term.

hep-th↗

arXiv2020

On the reformulation of Thomas-Fermi model to make it compatible to the Planck-scale

Thomas-Fermi model is considered here to make it cogent to capture the Planck-scale effect with the use of a generalization of uncertainty relation. Here generalization contains both linear and quadratic terms of momentum. We first reformulate the Thomas-Fermi model for the non-relativistic case. It has been shown that it can also be reformulated for taking into account the relativistic effect. Dialectic screening for the non-relativistic cases has been studied and the expression of screening length has been found out explicitly.

physics.gen-ph↗

arXiv2020

Planck-scale effect through a new MDR

In order to the expected Planck-scale correction in the physical systems we have put forwarded a novel modified dispersion relation (MDR). It has a generalized structure. A specific choice of the function used in the construction of this MDR, it has Lorentz invariance. A toy model like relativistic harmonic oscillator has been studied to get the necessary Planck-scale correction. It has been found that each laves of harmonic oscillator acquires Planck-scale correction and the result agrees with negligible deviation with the result obtained for this system for the same purpose using generalized uncertainty relation (GUP). The relativistic Hydrogen atom problem has also been studied with this MDR and it is found that like harmonic oscillator each energy level of the Hydrogen atom too has got Planck-scale correction.

physics.gen-ph↗

arXiv2019

Role of Faddeevian anomaly in the s-wave scattering of chiral fermion off dilaton black holes towards preservation of information

It was found that s-wave scattering of chiral fermion off dilaton black-hole when studied with a model generated from the chiral Schwinger model with standard Jackiw-Rajaraman type of anomaly provided information non preserving result. However this scattering problem when studied with a model generated from chiral Schwinger model with generalized Faddeevian type of anomaly. rendered information preserving result and it had well agreement with Hawking's revised proposal related to information loss. A minute and equitable investigation in detail has been carried out here to show how Faddeevian type of anomaly scores over the Jackiw-Rajaraman type of anomaly in connection with the s-wave scattering of chiral fermion of dilaton black-hole related to preservation of information.

hep-th↗

arXiv2019

Unparticle may be a Remedy to the Information Loss in the Scattering of Fermion off Dilaton Black-hole

We study s-wave scattering of fermion off dilaton black-hole. With one loop correction it was found to suffer from nonpreservation of information and that of course, went against Hawking's revised suggestion on this issue. A nonstandard approach, e.g. the probable existence of unparticle in $(1+1)$ dimension has been adopted here that shows a remedy to get rid of the danger of information loss to bring it in agrees with the Hawking's revised suggestion.

hep-th↗

arXiv2018

Investigations on a bi-chiral scalar field

Chiral boson fields in (1+1) dimensions obey a first order equation of motion. A second order equation which classically describes two chiral boson fields of the same chirality leads, however, to an unacceptable quantum theory

hep-th↗

arXiv2017

Gauged Floreanini-Jackiw type chiral boson and its BRST quantization

The gauged model of Siegel type chiral boson is considered. It has been shown that the action of gauged model of Floreanini-Jackiw (FJ) type chiral boson is contained in it in an interesting manner. A BRST invariant action corresponding to the action of gauged FJ type chiral boson has been formulated using Batalin, Fradkin and Vilkovisky based improved Fujiwara, Igarishi and Kubo (FIK) formalism. An alternative quantization of the gauge symmetric action has been made with a Lorentz gauge and an attempt has been made to establish the equivalence between the gauge symmetric version of the extended phase space and original gauge non-invariant version of the usual phase space.

hep-th↗

arXiv2016

On the BRST and finite field dependent BRST of a model where vector and axial vector interaction get mixed up with different weight

The generalized version of a lower dimensional model where vector and axial vector interaction get mixed up with different weight is considered. The bosonized version of which does not posses the local gauge symmetry. An attempt has been made here to construct BRST invariant reformulation of this model using Batalin Fradlin and Vilkovisky formalism. It is found that the extra field needed to make it gauge invariant turns into Wess-Zumino scalar with appropriate choice of gauge fixing. An application of finite field dependent BRST and anti-BRST transformation is also made here in order to show the transmutation between the BRST symmetric and the usual non-symmetric version of the model.

hep-th↗

arXiv2016

On the Poincaré and Gauge symmetry of a model where vector and axial vector interaction get mixed up with different weight

A $(1+1)$ dimensional model where vector and axial vector interaction get mixed up with different weight is considered with a generalized masslike term for gauge field. Through Poincaré algebra it has been made confirm that only a Lorentz covariant masslike term leads to a physically sensible theory as long as the number of constraints in the phase space is two. With that admissible masslike term, phase space structure of this model with proper identification of physical canonical pair has been determined using Diracs' scheme of quantization of constrained system. The bosonized version of the model remains gauge non-invariant to start with. Therefore, with the inclusion of appropriate Wess-Zumino term it is made gauge symmetric. An alternative quantization has been carried out over this gauge symmetric version to determine the phase space structure in this situation. To establish that the Wess-Zumino fields allocates themselves in the un-physical sector of the theory an attempts has been made to get back the usual theory from the gauge symmetric theory of the extended phase-space without hampering any physical principle. It has been found that the role of gauge fixing is crucial for this transmutation.

hep-th↗

arXiv2015

Chiral Thirring-Wess Model

The vector type of interaction of the Thirring-Wess model was replaced by the chiral type and a new model was presented which was termed as chiral Thirring-Wess model in \cite{THAR}. The model was studied there with a Faddeevian class of regularization. Few ambiguity parameters were allowed there with the apprehension that unitarity might be threatened like the chiral generation of the Schwinger model. In the present work it has been shown that no counter term containing the regularization ambiguity is needed for this model to be physically sensible. So the chiral Thirring-Wess model is studied here without the presence of any ambiguity parameter and it has been found that the model not only remains exactly solvable but also does not lose the unitarity like the chiral generation of the Schwinger model. The phase space structure and the theoretical spectrum of this new model have been determined in the present scenario. The theoretical spectrum is found to contain a massive boson with ambiguity free mass and a massless boson.

hep-th↗

arXiv2015

Chiral Thirring-Wess model with Faddeevian Regularization

Replacing vector type of interaction of the Thirring-Wess model by the chiral type a new model is presented which is termed here as chiral Thirring-Wess model. Ambiguity parameters of regularization is so chosen that the model falls into the Faddeevian class. The resulting Faddeevian class of model in general do not possess Lorentz invariance. However we can exploit the arbitrariness admissible in the ambiguity parameters to relate the quantum mechanically generated ambiguity parameters with the classical parameter involved in the masslike term of the gauge field which helps to maintain physical Lorentz invariance instead of the absence of manifestly lorentz covariance of the model. The the phase space structure and the theoretical spectrum of this class of model has been determined through Dirac's method of quantization of constraint system.

hep-th↗

arXiv2014

Unparticle in (1+1) dimension with one loop correction

The possibility of the presence of unparticle has been discussed recently adding a mass like term for gauge field with the Vector Schwinger model at the classical level \cite{GEOR1}. A one loop correction due to bosonization is taken into account and investigation is carried over to study the effect of it in connection with the unparticle scenario. It has been found that mass of the gauge boson acquires a generalized expression with the bare coupling constant and the parameters involved in the masslike terms added at the classical level term as well the terms entered in the model during the one loop correction needed for bosonization. So the physical mass viz., unparticle scale gets a new definition. The fermionic propagator is calculated which also agrees with the generalized mass term. A novel restoration of the lost gauge invariance reappears when the ambiguity parameter that entered into the effective action within the one loop correction acquires a specific expression with the bare coupling constant and the parameter involved in the masslike term of the gauge field added at the classical level.

hep-th↗