arXiv subjects

Qasem Exirifard

Publications and source records attributed to Qasem Exirifard.

At least 19 recordsLinked to original sources

arXiv2025

Beyond Poincaré Stresses: A Modern Quantum Field Theory Take on Hydrogen's Electromagnetic Mass

We revisit the longstanding electromagnetic mass problem from a modern quantum field theory perspective. Focusing on a system of two widely separated hydrogen atoms, one in an excited $nS$ state and the other in the ground $1S$ state, we isolate the electromagnetic contribution to the electron's total linear momentum by comparing the full energy-momentum tensor with the predictions of a point-like bound state model. Our analysis reveals that the leading perturbative correction introduces a factor $4/3$, which, along with subsequent corrections, indicates that the effective electromagnetic mass deviates from the conventional relation $E/c^2$. This discrepancy is attributed to the intrinsic nonlocality of the electromagnetic field, rather than to additional compensating mechanisms such as Poincaré stresses. We further contrast our quantum field theory results with the highly accurate predictions of the Schrödinger equation, which, despite neglecting higher-order terms, achieves an average error on the order of $10^{-5}\%$. Attempts to improve this accuracy via perturbative inclusion of the self-interaction of the electron's wave function instead increase the error, prompting a re-examination of the underlying perturbative assumptions. Our findings suggest that a non-perturbative treatment of the tree-level action may be required to fully capture the dynamics of bound states in quantum field theory.

hep-ph↗

arXiv2024

On the Electromagnetic Mass Dilemma

We show that a charged sphere moving at a constant velocity $v$ exhibits a mass due to electromagnetic radiation, expressed as $4/(3+(v/c)^2) (E/c^2)$, where $E$ is the electromagnetic energy and $c$ the speed of light in vacuum. Our finding reconciles the longstanding mismatch between the electromagnetic mass calculated from the classical electrodynamics' $4/3 (E/c^2)$ and the relativistic theory.

physics.gen-ph↗

arXiv2023

Trajectory of a massive localised wave function in a curved spacetime geometry

Propagation of a localised wave function of a massive scalar field is investigated in its rest frame. The complete orthogonal Hermite-Gauss basis is presented, and the Gouy phase and Rayleigh scale notions are adapted. The leading and sub-leading gravitational corrections to a localised quantum wave function propagating in a general curved spacetime geometry are calculated within the Fermi coordinates around the time-like geodesic of its rest frame, and cross-talk coefficients among the modes are derived. It is observed that spherically symmetric modes propagate along the geodesic. However, non-spherical modes are found to experience a mode-dependent residual quantum force at the sub-leading order. It is shown that the residual force does not generate an escape velocity for in-falling wave functions but leads to a mode-dependent deflection angle for the scattered ones.

gr-qc↗

arXiv2022

Gravitational distortion on photon state at the vicinity of the Earth

As a photon propagates along a null geodesic, the space-time curvature around the geodesic distorts its wave function. We utilise the Fermi coordinates adapted to a general null geodesic, and derive the equation for interaction between the Riemann tensor and the photon wave function. The equation is solved by being mapped to a time-dependent Schrödinger equation in $(2+1)$ dimensions. The results show that as a Gaussian time-bin wavepacket with a narrow bandwidth travels over a null geodesic, it gains an extra phase that is a function of the Riemann tensor evaluated and integrated over the propagation trajectory. This extra phase is calculated for communication between satellites around the Earth, and is shown to be measurable by current technology.

gr-qc↗

arXiv2021

Schrödinger equation in a general curved space-time geometry

We consider relativistic quantum field theory in the presence of an external electric potential in a general curved space-time geometry. We utilise Fermi coordinates adapted to the time-like geodesic to describe the low-energy physics in the laboratory and calculate the leading correction due to the curvature of the space-time geometry to the Schrödinger equation. We then compute the non-vanishing probability of excitation for a hydrogen atom that falls in or is scattered by a general Schwarzschild black hole. The photon that is emitted from the excited state by spontaneous emission extracts energy from the black hole, increases the decay rate of the black hole and adds to the information paradox.

gr-qc↗

arXiv2021

Towards Communication in a Curved Spacetime Geometry

The current race in quantum communication -- endeavouring to establish a global quantum network -- must account for special and general relativistic effects. The well-studied general relativistic effects include Shapiro time-delay, gravitational lensing, and frame dragging which all are due to how a mass distribution alters geodesics. Here, we report how the curvature of spacetime geometry affects the propagation of information carriers along an arbitrary geodesic. An explicit expression for the distortion onto the carrier wavefunction in terms of the Riemann curvature is obtained. Furthermore, we investigate this distortion for anti-de Sitter and Schwarzschild geometries. For instance, the spacetime curvature causes a 0.10~radian phase-shift for communication between Earth and the International Space Station on a monochromatic laser beam and quadrupole astigmatism can cause a 12.2 % cross-talk between structured modes traversing through the solar system. Our finding shows that this gravitational distortion is significant, and it needs to be either pre- or post-corrected at the sender or receiver to retrieve the information.

gr-qc↗

arXiv2019

Gravitomagnetism in Modified theory of Gravity

We study the gravitomagnetism in the Scalar-Vector-Tensor theory or Moffat's Modified theory of Gravity(MOG). We compute the gravitomagnetic field that a slow-moving mass distribution produces in its Newtonian regime. We report that the consistency between the MOG gravitomagnetic field and that predicted by the Einstein's gravitional theory and measured by Gravity Probe B, LAGEOS and LAGEOS 2, and with a number of GRACE and Laser Lunar ranging measurements requires $|α| < 0.0013$. We provide a discussion.

gr-qc↗

arXiv2019

GravitoMagnetic Field in Tensor-Vector-Scalar Theory

We study the gravitomagnetism in the TeVeS theory. We compute the gravitomagnetic field that a slow-moving mass distribution produces in its Newtonian regime. We report that the consistency between the TeVeS gravitomagnetic field and that predicted by the Einstein-Hilbert theory leads to a relation between the vector and scalar coupling constants of the theory. We observe that requiring consistency between the near horizon geometry of a black hole in TeVeS and the image of the black hole taken Event Horizon Telescope leads to another relation between the coupling constants of the TeVeS theory and enable us to identify the coupling constants of the theory.

gr-qc↗

arXiv2015

Randers geometry as MOND/dark matter

We consider a deviation of the physical length from the Riemann geometry toward the Randers'. We construct a consistent second-order relativistic theory of gravity that dynamically reduces to the Einstein-Hilbert theory for the strong and Newtonian gravity while its weak gravitational regime reproduces MOND and the gravitational lensing attributed to the dark matter halo. It also naturally accommodates the observed value of the cosmological constant. We show that it predicts a few percent deviation for the post Newtonian parameter $γ$ in a part of the regime that interpolates the Newtonian regime to the MOND regime. The deviation is consistent with the reported observations but can possibly be detected by fine-tuned refinements of the current data or specified future observations.

gr-qc↗

arXiv2014

Gauge Vectors-Tensor Gravity

We review and extend the Gauge Vectors-Tensor gravity: a covariant theory of gravity composed of a metric and gauge fields, leading to simple second order partial differential equations of motion, whose Newtonian and strong limits coincide to those of the Einsten-Hilbert action but the physics of its very weak fields should be identified through observation. We show that GVT is at least as dynamically stable as the Einstein-Hilbert gravity. It accommodates the MOND paradigm. We study its gravitational light deflection. We show that the post Newtonian parameter of $γ$ vanishes in the MOND regime of GVT gravity. Since $Λ$CDM assumes that $γ=1$, this suggests to observationally measure the $γ$ parameter in the weak regime of gravity as either a test for $Λ$CDM or GVT models

gr-qc↗

arXiv2014

Triangular Ring Resonator: Direct measurement of the parity-odd parameters of the photon sector of SME

We introduce the the Triangular Ring (TR) resonator. We show that the difference between the clockwise and anti-clockwise resonant frequencies of a vacuum TR resonator is sensitive to the birefringence parity-odd parameters of the photon's sector of the minimal Standard Model Extension (mSME): the Standard Model plus all the perturbative parameters encoding the break the Lorentz symmetry. We report that utilizing the current technology allows for direct measurement of these parameters with a sensitivity of the parity even ones and improves the best current resonator bounds by couple of orders of magnitudes. We note that designing an optical table that rotates perpendicular to the gravitational equipotential surface (geoid) allows for direct measurement of the constancy of the light speed at the vicinity of the earth in all directions in particular perpendicular to the geoid. If this table could achieve the precision of the ordinary tables, then it would improve the GPS bounds on the constancy of the light speed perpendicular to geoid by about eight orders of magnitude.

gr-qc↗

arXiv2013

GravitoMagnetic Force in Modified Newtonian Dynamics

We introduce the Gauge Vector-Tensor (GVT) theory by extending the AQUAL's approach to the GravitoElectroMagnetism (GEM) approximation of gravity. GVT is a generally covariant theory of gravity composed of a pseudo Riemannian metric and two U(1) gauge connections that reproduces MOND in the limit of very weak gravitational fields while remains consistent with the Einstein-Hilbert gravity in the limit of strong and Newtonian gravitational fields. GVT also provides a simple framework to study the GEM approximation to gravity. We illustrate that the gravitomagnetic force at the edge of a galaxy can be in accord with either GVT or ΛCDM but not both. We also study the physics of the GVT theory around the gravitational saddle point of the Sun and Jupiter system. We notice that the conclusive refusal of the GVT theory demands measuring either both of the gravitoelectric and gravitomagnetic fields inside the Sun-Jupiter MOND window, or the gravitoelectric field inside two different solar GVT MOND windows. The GVT theory, however, will be favored by observing an anomaly in the gravitoelectric field inside a single MOND window.

gr-qc↗

arXiv2013

Lunar system constraints on the modified theories of gravity

The MOND paradigm to the missing mass problem requires introducing a functional that is to be identified through observations and experiments. We consider AQUAL theory as a realization of the MOND. We show that the accurate value of the Earth GM measured by the Lunar Laser Ranging and that by various artificial Earth satellites, including the accurate tracking of the LAGEOS satellites, constrain this functional such that some of the chosen/proposed functional are refuted.

gr-qc↗

arXiv2013

Measuring gravitational behavior at short distances in space: A local test for MOND/MOG

We consider the AQUAL theory - a theory of modified gravity capable of resolving the missing mass problem - and study its predictions for micro gravity tests at the gravitational saddle points of the Solar system. We report that the AQUAL model enhances the gravity at the sub-micrometer ranges around the gravitational saddle points in a way that so far has been unnoticed. This enhancement can be measured. We, therefore, call for moving toward implementing micrometer gravity tests within the Solar gravitational saddle points.

gr-qc↗

arXiv2013

Physics in a general length space-time geometry: Call for experimental revision of the light speed anisotropy

We present a phenomenological model for the nature in the Finsler and Randers space-time geometries. We show that the parity-odd light speed anisotropy perpendicular to the gravitational equipotential surfaces encodes the deviation from the Riemann geometry toward the Randers geometry. We utilize an asymmetrical ring resonator and propose a setup in order to directly measure this deviation. We address the constraints that the current technology will impose on the deviation should the anisotropy be measured on the Earth surface and the orbits of artificial satellites.

gr-qc↗

arXiv2011

Optical diode based on the one-way light-speed anisotropy

We report that a triangular Fabry-Perot resonator filled with a parity-odd linear anisotropic medium exhibiting the one-way light speed anisotropy acts as a perfect diode. A Linear crystal such as the nematic liquid crystals whose molecular structures break parity can exhibit the one-way light speed anisotropy. The one-way light speed anisotropy also can be induced in a non-linear medium in the presence of constant electric and magnetic field strengths.

physics.optics↗

arXiv2011

Cosmological birefringent constraints on light

We calculate the birefringent in the vacuum for light at the leading and sub-leading orders for the CPT-even part of the SME. We report that all the LIV coefficients absent in the leading order, but the isotropic one, contributes to the sub-leading order birefringent. We consider models free of the first order birefringent. We then show that infrared, optical, and ultraviolet spectropolarimetry of cosmological sources bound the LIV coefficients to less than $ 10^{-16}$. This improves the best current bound on the parity-odd coefficients by two orders of magnitude and establishes the isotropy of the one-way light speed with the precision of $41 \frac{nm}{s}$.

gr-qc↗

arXiv2010

Matrix Model for membrane and dynamics of D-Particles in a curved space-time geometry and presence of form fields

We study dynamics of a membrane and its matrix regularisation. We present the matrix regularisation for a membrane propagating in a curved space-time geometry in the presence of an arbitrary 3-form field. In the matrix regularisation, we then study the dynamics of D-particles. We show how the Riemann curvature of the target space-time geometry, or any other form fields can polarise the D-Particles, cause entanglement among them and create fuzzy solutions. We review the fuzzy sphere and we present fuzzy hyperbolic and ellipsoid solutions.

hep-th↗