A b stra ct : Interacting models o f n | chiral bosons and gauge bosons in two dim ensions ore co... more A b stra ct : Interacting models o f n | chiral bosons and gauge bosons in two dim ensions ore considered. The constraint structures are analysed and the physical spectra determined for tw o regularizations which lead to Lorentz invariant theories. The gauge bosons becom e massive in both cases. The number o f unconfined chiral bosons is nj o r n in ? depending on the regularization* K eyw ord : Gauged chiral boson P A C S N os. : l l. l 5 .-q , ll.1 0 .E f, II lOKk
We consider non-commutating Simpson-Visser spacetime and study the superradiance phenomena and th... more We consider non-commutating Simpson-Visser spacetime and study the superradiance phenomena and the shadow cast by the back hole associated with this modified spacetime. We extensively study the different aspects of the black hole associated with the metric endowed with the corrections linked with non-commutative properties of spacetime. We study the superradiance effect, deviation of shape, size of the ergosphere, and the shadow of black hole in this extended situation and look into their variation taking different values Simpson-Visser parameter ℓ and non-commutative parameter b. We have made an attempt to constrain the parameter ℓ using the data available from the EHT collaboration for M 87 * black hole. Our study reveals that black holes are associated with noncommutative Simpson-Visser spacetime may be a suitable candidate for an astrophysical black hole.
We investigate the impact of quantum gravity on the thermodynamic characteristics and radiation p... more We investigate the impact of quantum gravity on the thermodynamic characteristics and radiation processes of thin accretion disks surrounding Schwarzschild-like black holes. To incorporate quantum gravity into our study, we apply the framework of generalization of uncertainty, which is equivalent to the renormalization group improved quantum gravity and maintains the limit of asymptotically safe preposition of gravity. A free parameter, reflecting the quantum effects on spacetime geometry, is introduced to enable the study of the thermal properties of the black hole itself and the accretion disk surrounding it at the quantum level. We explicitly calculate the entropy, temperature, free energy, and enthalpy of the modified black hole and show how they vary with the free parameter encoding the quantum effects. Moreover, we provide estimations of the quantum correction to the time-averaged energy flux, temperature of the disk, differential luminosity, and the conversion efficiency of a...
We consider the gauged model of Siegel type chiral boson with a Lorentz non-covariant mass-like t... more 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 a model of boson where the kinetic term is like the kinetic term 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.
The results and calculations of the article [1] are found erroneous for a generic r and it remain... more The results and calculations of the article [1] are found erroneous for a generic r and it remains irremediable in general. However for r = 0, r = ±1, and r >> 1 it may be physically acceptable.
In this manuscript, we consider the hairy Schwarzschild black hole that evades the no-hair theore... more In this manuscript, we consider the hairy Schwarzschild black hole that evades the no-hair theorem. The hair is induced by an additional source from surroundings, such as dark matter, that has a constant energy-momentum tensor(EMT). We study the strong gravitational lensing of light in the background of the hairy Schwarzschild black hole. We observe that the lensing coefficient a increases with α but decreases with ℓ0. The opposite effect is observed for the lensing coefficient b and the impact parameter bm. We also notice that the angular position θ∞ decreases with α but increases with ℓ0, whereas the angular separation s increases with α and decreases with ℓ0. For all parameters mentioned, we regain their values for the Schwarzschild black hole whenever we put either α = 0 or ℓ0 = 1. With the help of the Gauss-Bonnet theorem, we briefly describe the weak gravitational lensing in the background of the hairy Schwarzschild black hole.
Chiral boson fields in (I + 1) dimensions obey a first order equation of motion. A second order e... more Chiral boson fields in (I + 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.
The generalized version of the chiral Schwinger which contains both the vector and axial-vector i... more The generalized version of the chiral Schwinger which contains both the vector and axial-vector interaction with unequal weight is exactly solvable. It contains a massive and a massless boson in its theoretical Spectra. However, after imposition of a chiral constrain it loses exactly solvability. So the theoretical spectrum can not be determined precisely and consequently, the mass generation and confinement aspect of fermion becomes unsettled which is in sharp disagreement with the recent publication [18].
We consider the gauged model of Siegel type chiral boson with a Lorentz non-covariant mass-like t... more 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 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.
The generalized version of a lower dimensional model where vector and axial vector interaction ge... more 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 the 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.
A calculational error was crept in the expression of the Hamiltonian (Eq. (14)) in original artic... more A calculational error was crept in the expression of the Hamiltonian (Eq. (14)) in original article. We give the correct form of the Hamiltonian and also the correct form of the subsequent equations which depend on the Hamiltonian. The corrections are all of numerical nature and do not affect the physical conclusions in any fundamental way. (c) 2006 Elsevier B.V. All rights reserved.
A Kerr–Sen-like black hole solution results from Einstein-bumblebee gravity. It contains a Lorent... more 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 $$\ell $$ ℓ takes the negative values and it reduces when values of $$\ell $$ ℓ are positive. The study of the black hole bomb issue reveals that for the negative values of $$\ell $$ ℓ , the parameter space of the scalar field instability increa...
We find that Siegel type chiral boson with a parameter-dependent Lorentz non-covariant masslike t... more We find that Siegel type chiral boson with a parameter-dependent Lorentz non-covariant masslike term for the gauge fields to be equivalent to the chiral Schwinger model with one parameter class of Faddeevian anomaly if the model is described in terms of Floreanini–Jackiw type chiral boson. By invoking the Wess–Zunino field gauge-invariant reformulation is made. It has been shown that the gauge-invariant model has the same physical content as its gauge non-invariant ancestor had. The BRST invariant effective action corresponding to this model has also been constructed. All the nilpotent symmetries associated with the BRST symmetry along with the bosonic, ghost, and discrete symmetries have been systematically studied. We establish that the nilpotent charges corresponding to these symmetries resemble the algebra of the de Rham cohomological operators in differential geometry. In the environment of conserved charges associated with the models, we study the Hodge decomposition theorem o...
We study the quantum gravity correction to the accretion onto the modified Schwarzschild black ho... more We study the quantum gravity correction to the accretion onto the modified Schwarzschild black hole in the GUP framework. The GUP which is associated with the minimum measurable length modifies the Schwarzschild black hole which gets endowed with quantum gravity correction. We examine the possible positions of critical points and obtain the critical velocity. For polytropic matter, we compute the correction to the temperature and the total integrated flux at the event horizon with reference to the minimum measurable length. We observe that accretion has a crucial dependence on the quantum effect of gravity marked by the GUP parameter.
We carry out an investigation imposing a chiral constraint in the phase space of vector and axial... more We carry out an investigation imposing a chiral constraint in the phase space of vector and axial-vector Schwinger model. We find that resulting models become identical to a 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.
A new generalization of the vector Schwinger model is considered where gauge symmetry is broken a... more A new generalization of the vector Schwinger model is considered where gauge symmetry is broken at the quantum mechanical level. By proper extension of the phase space this broken symmetry has been restored. Also an equivalent first class theory is reformulated in the actual phase space using Mitra and Rajaraman’s prescription [8, 9]. A BRST invariant effective action is also formulated. The new dynamical fields introduced, turn into Wess-Zumino scalar. 1 1
We consider two distinctly different gauged theories of Floreanini-Jackiw type chiral boson. Usin... more We consider two distinctly different gauged theories of Floreanini-Jackiw type chiral boson. Using the Batalin-Fradkin-Vilkovisky (BFV) technique, the nilpotent BRST, and anti-BRST symmetry transformations for these theories have been studied. Other forms of nilpotent symmetry transformations like co-BRST, and anti-co-BRST, which leave the gauge-fixing part of the action invariant, are also explored for these two models. We show that the nilpotent charges corresponding to these symmetries for both the models satisfy the algebra of the de Rham cohomological operators in differential geometry. The Hodge decomposition theorem on the compact manifold is also studied in the context of conserved charges for these two models. It has been found that despite the differences of constraint structures and the theoretical spectra the models exhibit identical symmetry properties.
A b stra ct : Interacting models o f n | chiral bosons and gauge bosons in two dim ensions ore co... more A b stra ct : Interacting models o f n | chiral bosons and gauge bosons in two dim ensions ore considered. The constraint structures are analysed and the physical spectra determined for tw o regularizations which lead to Lorentz invariant theories. The gauge bosons becom e massive in both cases. The number o f unconfined chiral bosons is nj o r n in ? depending on the regularization* K eyw ord : Gauged chiral boson P A C S N os. : l l. l 5 .-q , ll.1 0 .E f, II lOKk
We consider non-commutating Simpson-Visser spacetime and study the superradiance phenomena and th... more We consider non-commutating Simpson-Visser spacetime and study the superradiance phenomena and the shadow cast by the back hole associated with this modified spacetime. We extensively study the different aspects of the black hole associated with the metric endowed with the corrections linked with non-commutative properties of spacetime. We study the superradiance effect, deviation of shape, size of the ergosphere, and the shadow of black hole in this extended situation and look into their variation taking different values Simpson-Visser parameter ℓ and non-commutative parameter b. We have made an attempt to constrain the parameter ℓ using the data available from the EHT collaboration for M 87 * black hole. Our study reveals that black holes are associated with noncommutative Simpson-Visser spacetime may be a suitable candidate for an astrophysical black hole.
We investigate the impact of quantum gravity on the thermodynamic characteristics and radiation p... more We investigate the impact of quantum gravity on the thermodynamic characteristics and radiation processes of thin accretion disks surrounding Schwarzschild-like black holes. To incorporate quantum gravity into our study, we apply the framework of generalization of uncertainty, which is equivalent to the renormalization group improved quantum gravity and maintains the limit of asymptotically safe preposition of gravity. A free parameter, reflecting the quantum effects on spacetime geometry, is introduced to enable the study of the thermal properties of the black hole itself and the accretion disk surrounding it at the quantum level. We explicitly calculate the entropy, temperature, free energy, and enthalpy of the modified black hole and show how they vary with the free parameter encoding the quantum effects. Moreover, we provide estimations of the quantum correction to the time-averaged energy flux, temperature of the disk, differential luminosity, and the conversion efficiency of a...
We consider the gauged model of Siegel type chiral boson with a Lorentz non-covariant mass-like t... more 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 a model of boson where the kinetic term is like the kinetic term 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.
The results and calculations of the article [1] are found erroneous for a generic r and it remain... more The results and calculations of the article [1] are found erroneous for a generic r and it remains irremediable in general. However for r = 0, r = ±1, and r >> 1 it may be physically acceptable.
In this manuscript, we consider the hairy Schwarzschild black hole that evades the no-hair theore... more In this manuscript, we consider the hairy Schwarzschild black hole that evades the no-hair theorem. The hair is induced by an additional source from surroundings, such as dark matter, that has a constant energy-momentum tensor(EMT). We study the strong gravitational lensing of light in the background of the hairy Schwarzschild black hole. We observe that the lensing coefficient a increases with α but decreases with ℓ0. The opposite effect is observed for the lensing coefficient b and the impact parameter bm. We also notice that the angular position θ∞ decreases with α but increases with ℓ0, whereas the angular separation s increases with α and decreases with ℓ0. For all parameters mentioned, we regain their values for the Schwarzschild black hole whenever we put either α = 0 or ℓ0 = 1. With the help of the Gauss-Bonnet theorem, we briefly describe the weak gravitational lensing in the background of the hairy Schwarzschild black hole.
Chiral boson fields in (I + 1) dimensions obey a first order equation of motion. A second order e... more Chiral boson fields in (I + 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.
The generalized version of the chiral Schwinger which contains both the vector and axial-vector i... more The generalized version of the chiral Schwinger which contains both the vector and axial-vector interaction with unequal weight is exactly solvable. It contains a massive and a massless boson in its theoretical Spectra. However, after imposition of a chiral constrain it loses exactly solvability. So the theoretical spectrum can not be determined precisely and consequently, the mass generation and confinement aspect of fermion becomes unsettled which is in sharp disagreement with the recent publication [18].
We consider the gauged model of Siegel type chiral boson with a Lorentz non-covariant mass-like t... more 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 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.
The generalized version of a lower dimensional model where vector and axial vector interaction ge... more 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 the 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.
A calculational error was crept in the expression of the Hamiltonian (Eq. (14)) in original artic... more A calculational error was crept in the expression of the Hamiltonian (Eq. (14)) in original article. We give the correct form of the Hamiltonian and also the correct form of the subsequent equations which depend on the Hamiltonian. The corrections are all of numerical nature and do not affect the physical conclusions in any fundamental way. (c) 2006 Elsevier B.V. All rights reserved.
A Kerr–Sen-like black hole solution results from Einstein-bumblebee gravity. It contains a Lorent... more 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 $$\ell $$ ℓ takes the negative values and it reduces when values of $$\ell $$ ℓ are positive. The study of the black hole bomb issue reveals that for the negative values of $$\ell $$ ℓ , the parameter space of the scalar field instability increa...
We find that Siegel type chiral boson with a parameter-dependent Lorentz non-covariant masslike t... more We find that Siegel type chiral boson with a parameter-dependent Lorentz non-covariant masslike term for the gauge fields to be equivalent to the chiral Schwinger model with one parameter class of Faddeevian anomaly if the model is described in terms of Floreanini–Jackiw type chiral boson. By invoking the Wess–Zunino field gauge-invariant reformulation is made. It has been shown that the gauge-invariant model has the same physical content as its gauge non-invariant ancestor had. The BRST invariant effective action corresponding to this model has also been constructed. All the nilpotent symmetries associated with the BRST symmetry along with the bosonic, ghost, and discrete symmetries have been systematically studied. We establish that the nilpotent charges corresponding to these symmetries resemble the algebra of the de Rham cohomological operators in differential geometry. In the environment of conserved charges associated with the models, we study the Hodge decomposition theorem o...
We study the quantum gravity correction to the accretion onto the modified Schwarzschild black ho... more We study the quantum gravity correction to the accretion onto the modified Schwarzschild black hole in the GUP framework. The GUP which is associated with the minimum measurable length modifies the Schwarzschild black hole which gets endowed with quantum gravity correction. We examine the possible positions of critical points and obtain the critical velocity. For polytropic matter, we compute the correction to the temperature and the total integrated flux at the event horizon with reference to the minimum measurable length. We observe that accretion has a crucial dependence on the quantum effect of gravity marked by the GUP parameter.
We carry out an investigation imposing a chiral constraint in the phase space of vector and axial... more We carry out an investigation imposing a chiral constraint in the phase space of vector and axial-vector Schwinger model. We find that resulting models become identical to a 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.
A new generalization of the vector Schwinger model is considered where gauge symmetry is broken a... more A new generalization of the vector Schwinger model is considered where gauge symmetry is broken at the quantum mechanical level. By proper extension of the phase space this broken symmetry has been restored. Also an equivalent first class theory is reformulated in the actual phase space using Mitra and Rajaraman’s prescription [8, 9]. A BRST invariant effective action is also formulated. The new dynamical fields introduced, turn into Wess-Zumino scalar. 1 1
We consider two distinctly different gauged theories of Floreanini-Jackiw type chiral boson. Usin... more We consider two distinctly different gauged theories of Floreanini-Jackiw type chiral boson. Using the Batalin-Fradkin-Vilkovisky (BFV) technique, the nilpotent BRST, and anti-BRST symmetry transformations for these theories have been studied. Other forms of nilpotent symmetry transformations like co-BRST, and anti-co-BRST, which leave the gauge-fixing part of the action invariant, are also explored for these two models. We show that the nilpotent charges corresponding to these symmetries for both the models satisfy the algebra of the de Rham cohomological operators in differential geometry. The Hodge decomposition theorem on the compact manifold is also studied in the context of conserved charges for these two models. It has been found that despite the differences of constraint structures and the theoretical spectra the models exhibit identical symmetry properties.
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