A mechanism to generate varying speed of light via Higgs-dilaton coupling: Theory and cosmological applications

TL;DR

This paper proposes a novel mechanism where the Higgs-dilaton coupling causes fundamental constants like the speed of light and Planck's constant to vary with the dilaton field, leading to new cosmological phenomena and potential solutions to dark energy and Hubble tension issues.

Contribution

It introduces an alternative way to link the Higgs field with fundamental constants, enabling their variation across spacetime and impacting cosmological models.

Findings

Variation of c and ħ can explain supernova observations without dark energy

Modified redshift and Hubble law accommodate CMB data without dark energy

Potential resolution of H_0 tension through variable speed of light

Abstract

We allow the Higgs field $\Phi$ to interact with a dilaton field $\chi$ of the background spacetime via the coupling $\chi^2\,\Phi^\dagger\Phi$. Upon spontaneous gauge symmetry breaking, the Higgs VEV becomes proportional to $\chi$. While traditionally this linkage is employed to make the Planck mass and particle masses dependent on $\chi$, we present an $\textit alternative$ mechanism: the Higgs VEV will be used to construct Planck's constant $\hbar$ and speed of light $c$. Specifically, each open set vicinity of a given point $x^*$ on the spacetime manifold is equipped with a replica of the Glashow-Weinberg-Salam action operating with its own effective values of $\hbar_*$ and $c_*$ per $\hbar_*\propto\chi^{-1/2}(x^*)$ and $c_*\propto\chi^{1/2}(x^*)$, causing these ``fundamental constants'' to vary alongside the dynamical field $\chi$. Moreover, in each open set around $x^*$, the prevailing value $\chi(x^*)$ determines the length and time scales for physical processes occurring in this region as $l\propto\chi^{-1}(x^*)$ and $\tau\propto\chi^{-3/2}(x^*)$. This leads to an $\textit anisotropic$ relation $\tau^{-1}\propto l^{-3/2}$ between the rate of clocks and the length of rods, resulting in a distinct set of novel physical phenomena. For late-time cosmology, the variation of $c$ along the trajectory of light waves from distant supernovae towards the Earth-based observer necessitates modifications to the Lema\^itre redshift relation and the Hubble law. These modifications are capable of: (1) Accounting for the Pantheon Catalog of SNeIa $\textit{through a declining speed of light in an expanding Einstein--de Sitter universe}$, thus avoiding the need for dark energy; (2) Revitalizing Blanchard-Douspis-Rowan-Robinson-Sarkar's CMB power spectrum analysis that bypassed dark energy [A&A 412, 35 (2003)]; and (3) Resolving the $H_0$ tension without requiring a dynamical dark energy component.