arXiv subjects

Mousumi Maitra

Publications and source records attributed to Mousumi Maitra.

5 recordsLinked to original sources

arXiv2025

Holographic symmetry algebra for the MHV sector revisited

We revisit the holographic symmetry algebra in the MHV sector. We find an infinite dimensional Abelian symmetry algebra whose generators are the conformally soft negative helicity gravitons and gluons. So the complete symmetry algebra in the MHV graviton sector is a semideirect product of the $w_{1+\infty}$ algebra and the infinite dimensional Abelian algebra. Similarly in the MHV gluon sector the symmetry algebra is a semidirect product of the $S$ algebra and the infinite dimensional Abelian algebra. The extended symmetry algebra has some use. For example, it is known for sometime that an $n$ point MHV amplitude satisfies $(n-2)$ Knizhnik-Zamolodchikov (KZ) type equations. So two equations are missing. We show that the extended symmetry algebra has additional null states whose decoupling give rise to the two missing equations.

hep-th↗

arXiv2021

BMS Goldstone modes near the horizon of a Kerr black hole are thermal

Near horizon Bondi-Metzner-Sachs (BMS) like symmetry is spontaneously broken by the black hole background itself and hence gives rise to Goldstone mode. The associated Goldstone mode for the near horizon BMS like symmetry of a Schwarzschild black hole was found to behave like inverted harmonic oscillators, which has been further shown to lead to thermodynamic temperature in the semi-classical regime. Here we investigate the generalization of this previous findings for the Kerr black hole. The analysis is being performed for two different situations. Firstly, we analyze Goldstone mode dynamics considering {\it slowly rotating} Kerr. In other case the problem is solved in the frame of {\it zero angular momentum observer} (ZAMO) with arbitrary value of rotation. In both analysis the effective semi-classical temperature of Goldstone modes turn out to be proportional to that of Hawking temperature. Due to such similarity and generality we feel that these Goldstone modes may play important role to understand the underlying microscopic description of horizon thermalization.

gr-qc↗

arXiv2021

Diffeomorphism symmetries near a timelike surface in black hole spacetime

Recently symmetries of gravity and gauge fields in the asymptotic regions of spacetime have been shown to play vital role in their low energy scattering phenomena. Further, for the black hole spacetime, near horizon symmetry has been observed to play possible role in understanding the underlying degrees of freedom for thermodynamic behaviour of horizon. Following the similar idea, in this paper, we analyzed the symmetry and associated algebra near a timelike surface which is situated at any arbitrary radial position and is embedded in black hole spacetime. In this paper we considered both Schwarzschild and Kerr black hole spacetimes. The families of hypersurfaces with constant radial coordinate (outside the horizon) in these spacetimes is timelike in nature and divide the space into two distinct regions. The symmetry algebra turned out to be reminiscent of Bondi-Metzner-Sach (BMS) symmetry, found in the asymptotic null infinity.

gr-qc↗

arXiv2020

Near horizon symmetries, emergence of Goldstone modes and thermality

For a long time it is believed that black hole horizon are thermal and quantum mechanical in nature. The microscopic origin of this thermality is the main question behind our present investigation, which reveals possible importance of near horizon symmetry. It is this symmetry which is assumed to be spontaneously broken by the background spacetime, generates the associated Goldstone modes. In this paper we construct a suitable classical action for those Goldstone modes, and show that all the momentum modes experience nearly the same inverted harmonic potential, leading to an instability. Thanks to the recent conjectures on the chaos and thermal quantum system, particularly in the context of an inverted harmonic oscillator system. Going into the quantum regime, the system of large number of Goldstone modes with the aforementioned instability is shown to be inherently thermal. Interestingly the temperature of the system also turns out to be proportional to that of the well known horizon temperature. Therefore, we hope our present study can illuminate an intimate connection between the horizon symmetries and the associated Goldstone modes as a possible mechanism of the microscopic origin of the horizon thermality.

hep-th↗

arXiv2018

Symmetries near a generic charged null surface and associated algebra: an off-shell analysis

To understand the underlying degrees of freedom, near horizon symmetry analysis of a black has gain significant interest in the recent past. In this paper we generalized those analysis first by taking into account a generic null surface carrying $U(1)$ electromagnetic charge. With the appropriate boundary conditions near the surface under study, we identified the symmetry algebra among the subset of diffeomporphism and gauge generators which preserve the metric of the null surface and the form of the gauge field configuration. With the knowledge of those symmetries we further derived the algebra among the associated charges considering general Lanczos-Lovelock gravity theory and gauge theory. Importantly while computing the charges we not only considered general theory, but also used off-shell formalism which is believed to play crucial role in understanding quantum gravity. Both the non-extremal and extremal cases are addressed here.

gr-qc↗