arXiv subjects

Reza Javadinezhad

Publications and source records attributed to Reza Javadinezhad.

7 recordsLinked to original sources

arXiv2026

Gravitational Holonomy in Sagnac Interferometry

We analyze the influence of gravitational waves on a Sagnac interferometer formed by the interference of two counter-propagating beams traversing a closed spatial loop. In addition to the well-known Sagnac phase shift, we identify an additional contribution originating from a relative rotation in the polarization vectors. We formulate this effect as a gravitational holonomy associated to the internal Lorentz group. The magnitude of both effects is computed due to gravitational waves generated by a localized source far from the detector, at leading order in the inverse distance. For freely falling observers, the phase shift is zero and the polarization rotation becomes the dominant effect.

gr-qc↗

arXiv2025

Lorentz Covariant Supertranslation Frames for the Angular Momentum Aspect

In this letter, we review the well known ambiguity in defining angular momentum (and mass dipole) fluxes in general relativity and we reinterpret recent works that resolve the ambiguity by defining invariant charges. We resolve the ambiguity by finding the conditions that fix a frame for supertranslation and for space-time translation. We also present an elementary method for measuring the angular momentum aspect and work out explicitly the supertranslation frame-fixing conditions for the metric created by point particles to first nontrivial order in the Newton constant.

gr-qc↗

arXiv2024

Three Puzzles with Covariance and Supertranslation Invariance of Angular Momentum Flux (with Solutions)

We describe and solve three puzzles arising in covariant and supertranslation-invariant formulas for the flux of angular momentum and other Lorentz charges in asymptotically flat spacetimes: 1) Supertranslation-invariance and covariance imply invariance under spacetime translations; 2) the flux depends on redundant auxiliary degrees of freedom that cannot be set to zero in all Lorentz frames without breaking Lorentz covariance; 3) supertranslation-invariant Lorentz charges do not generate the transformations of the Bondi mass aspect implied by the isometries of the asymptotic metric. In this letter, we solve the first two puzzles by presenting covariant formulas that unambiguously determine the auxiliary degrees of freedom and clarify the last puzzle by explaining the different role played by covariant and canonical charges. Our construction makes explicit the choice of reference frame underpinning seemingly unambiguous results presented in the current literature.

hep-th↗

arXiv2022

A Supertranslation-Invariant Formula for the Angular Momentum Flux in Gravitational Scattering

The angular momentum radiated in gravitational scattering can be changed by performing a supertranslation of the asymptotic metric, i.e. by adding radiation with infinite wavelenght to the metric. This puzzling property can be avoided by adopting a supertranslation-invariant definition of the angular momentum flux in general relativity. Definitions currently available in the literature cannot reproduce the flux necessary to obtain the correct radiation reaction effects in gravitational scattering. They also disagree with computations of the flux performed using scattering amplitudes and soft graviton theorems. In this paper we provide a new supertranslation-invariant definition of the angular momentum flux in gravitational scattering that uses only asymptotic metric data and reproduces the flux necessary to obtain the correct radiation reaction effects.

gr-qc↗

arXiv2022

Supertranslation-Invariant Dressed Lorentz Charges

We present an explicit formula for Lorentz boosts and rotations that commute with BMS supertranslations in asymptotically flat spacetimes. Key to the construction is the use of infrared regularizations and of a unitary transformation that makes observables commute with the soft degrees of freedom. We explicitly verify that our charges satisfy the Lorentz algebra and we check that they are consistent with expectations by evaluating them on the supertranslated Minkowski space and on the boosted Kerr black hole.

hep-th↗

arXiv2019

Comments on Lorentz Transformations, Dressed Asymptotic States and Hawking Radiation

We consider two applications of the factorization of infrared dynamics in QED and gravity. The first is a redefinition of the Lorentz transformations that makes them commute with supertranslations. The other is the process of particle creation near a black hole horizon. For the latter we show that the emission of soft particles factors out of the S-matrix in the fixed-background approximation and to leading order in the soft limit. The factorization is implemented by dressing the incoming and outgoing asymptotic states with clouds of soft photons and soft gravitons. We find that while the soft photon cloud has no effect, the soft graviton cloud induces a phase shift in the Bogolyubov coefficients relating the incoming and outgoing modes. However, the flux of outgoing particles, given by the absolute value of the Bogolyubov coefficient, is insensitive to this phase.

hep-th↗

arXiv2016

Relativistic virial relation for cosmological structures

Starting with the relativistic Boltzmann equation for a system of particles defined by a distribution function, we have derived the virial relation for a spherical structure within an expanding background in the context of general relativity. This generalized form of the virial relation is then applied to the static case of a spherically symmetric structure to see the difference in the simplest case to the Newtonian relation. A relativistic Mass-Temperature relation for this simple case is also derived which can be applied to compact objects in astrophysics. Our general virial relation is then applied to the non-static case of a structure within an expanding universe where an extra term, usually missed in studies of structures in the presence of the dark energy, appears.

gr-qc↗