arXiv subjects

John Moffat

Publications and source records attributed to John Moffat.

8 recordsLinked to original sources

arXiv2025

Void and Density Walls Inhomogeneous Cosmic Web Cosmology

An approach to cosmological modelling is presented that incorporates the inhomogeneous structure of the Cosmic Web, specifically focusing on the interplay between cosmic voids and density walls. We extend the standard homogeneous and isotropic cosmological model to account for the observed large-scale structure of the universe. By modifying the Friedmann equations to include inhomogeneity terms representing voids and walls, we develop a more realistic description of cosmic evolution. Our model demonstrates how the presence of these structures affects the overall expansion rate of the universe and the growth of perturbations. We find that accounting for this inhomogeneous distribution leads to significant deviations from the predictions of standard $\Lambda$CDM cosmology in the late-time universe. The Hubble and $\sigma_8$ structure growth tensions are addressed in the void-density wall model, leading to a resolution of these tensions. These results have important implications for the interpretation of cosmological observations when including the void and density wall Cosmic Web inhomogeneities.

astro-ph.CO↗

arXiv2024

Formation and Growth of the First Supermassive Black Holes in MOG

The emergence of supermassive black holes (SMBHs) in the early universe remains a topic of profound interest and debate. In this paper, we investigate the formation and growth of the first SMBHs within the framework of Modified Gravity (MOG), where gravity exhibits increased strength. We explore how MOG, as an alternative to the standard model, may offer novel insights into the emergence of SMBHs and potentially reconcile the discrepancies observed in the accretion and growth processes. We examine the dynamics of gas and matter in this modified gravitational framework, shedding light on the unique interplay between gravity and the formation of SMBHs.

astro-ph.GA↗

arXiv2024

Nonlocal Quantum Field Theory and Quantum Entanglement

We discuss the nonlocal nature of quantum mechanics and the link with relativistic quantum mechanics such as formulated by quantum field theory. We use here a nonlocal quantum field theory (NLQFT) which is finite, satisfies Poincaré invariance, unitarity and microscopic causality. This nonlocal quantum field theory associates infinite derivative entire functions with propagators and vertices. We focus on proving causality and discussing its importance when constructing a relativistic field theory. We formulate scalar field theory using the functional integral in order to characterize quantum entanglement and the entanglement entropy of the theory. Using the replica trick, we compute the entanglement entropy for the theory in 3 + 1 dimensions on a cone. The result is free of UV divergences and we recover the area law.

hep-th↗

arXiv2018

Quasinormal Modes of Modified Gravity (MOG) Black Holes

The Quasinormal modes (QNMs) for gravitational and electromagnetic perturbations are calculated in a Scalar-Tensor-Vector (Modified Gravity) spacetime, which was initially proposed to obtain correct dynamics of galaxies and galaxy clusters without the need for dark matter. It is found that for the increasing model parameter $α$, both the real and imaginary parts of the QNMs decrease compared to those for a standard Schwarzschild black hole. On the other hand, when taking into account the $1/(1+α)$ mass re-scaling factor present in MOG, Im($ω$) matches almost identically that of GR, while Re($ω$) is higher. These results can be identified in the ringdown phase of massive compact object mergers, and are thus timely in light of the recent gravitational wave detections by LIGO.

gr-qc↗

arXiv2012

Fundamental quantum optics experiments conceivable with satellites -- reaching relativistic distances and velocities

Physical theories are developed to describe phenomena in particular regimes, and generally are valid only within a limited range of scales. For example, general relativity provides an effective description of the Universe at large length scales, and has been tested from the cosmic scale down to distances as small as 10 meters. In contrast, quantum theory provides an effective description of physics at small length scales. Direct tests of quantum theory have been performed at the smallest probeable scales at the Large Hadron Collider, ${\sim} 10^{-20}$ meters, up to that of hundreds of kilometers. Yet, such tests fall short of the scales required to investigate potentially significant physics that arises at the intersection of quantum and relativistic regimes. We propose to push direct tests of quantum theory to larger and larger length scales, approaching that of the radius of curvature of spacetime, where we begin to probe the interaction between gravity and quantum phenomena. In particular, we review a wide variety of potential tests of fundamental physics that are conceivable with artificial satellites in Earth orbit and elsewhere in the solar system, and attempt to sketch the magnitudes of potentially observable effects. The tests have the potential to determine the applicability of quantum theory at larger length scales, eliminate various alternative physical theories, and place bounds on phenomenological models motivated by ideas about spacetime microstructure from quantum gravity. From a more pragmatic perspective, as quantum communication technologies such as quantum key distribution advance into Space towards large distances, some of the fundamental physical effects discussed here may need to be taken into account to make such schemes viable.

quant-ph↗

arXiv2012

Identification of the 125 GeV Resonance as a Pseudoscalar Quarkonium Meson

The 125 GeV resonance discovered at the LHC could be a heavy quarkonium pseudoscalar meson. The diagonalization of the mass matrix of the isoscalar quarkonium states $|ζ>$ and $|ζ^{0'}>$ produces the states identified with the pseudoscalar heavy quarkonium mesons $ζ^0$ and $ζ^{0'}$. For a mixing angle $ϕ\sim 36\,^{\circ}$ the mass of the bound state pseudoscalar resonance $ζ^0$ is $m_{ζ^0}\sim 125$ GeV. The decay rates of the quarkonium $ζ^0$ meson are estimated and compared to the standard model Higgs boson predictions. The importance of determining the spin-parity of the 125 GeV resonance is discussed. Criteria for experimentally discriminating between the pseudoscalar, $J^{PC}=0^{-+}$, $ζ^0$ quarkonium meson and the scalar $J^{PC}=0^{++}$ Higgs boson are investigated.

hep-ph↗

arXiv2011

Ultraviolet Complete Electroweak Model Without a Higgs Particle

An electroweak model with running coupling constants described by an energy dependent entire function is utraviolet complete and avoids unitarity violations for energies above 1 TeV. The action contains no physical scalar fields and no Higgs particle and the physical electroweak model fields are local and satisfy microcausality. The $W$ and $Z$ masses are compatible with a symmetry breaking $SU(2)_L\times U(1)_Y \rightarrow U(1)_{\rm em}$, which retains a massless photon. The vertex couplings possess an energy scale $Λ_W > 1$ TeV predicting scattering amplitudes that can be tested at the LHC.

hep-ph↗

arXiv2004

The Gravitational Instability of the Vacuum: Insight into the Cosmological Constant Problem

A mechanism for suppressing the cosmological constant is developed, based on an analogy with a superconducting phaseshift in which free fermions coupled perturbatively to a weak gravitational field are in an unstable false vacuum state. The coupling of the fermions to the gravitational field generates fermion condensates with zero momentum and a phase transition induces a nonperturbative transition to a true vacuum state by producing a positive energy gap $Δ$ in the vacuum energy, identified with $\sqrtΛ$, where $Λ$ is the cosmological constant. In the strong coupling limit a large cosmological constant induces a period of inflation in the early universe, followed by a weak coupling limit in which $\sqrtΛ$ vanishes exponentially fast as the universe expands due to the dependence of the energy gap on the density of Fermi surface fermions, $D(ε)$, predicting a small cosmological constant in the present universe.

hep-th↗