String-inspired running-vacuum cosmology, quantum corrections and the current cosmological tensions

TL;DR

This paper explores quantum corrections in a string-inspired running vacuum model of cosmology, showing they can help resolve current tensions in measurements of the Hubble constant and structure growth, especially in supergravity-based scenarios.

Contribution

It introduces quantum corrections to the running vacuum model from graviton loops and matter fields, highlighting their potential to address cosmological tensions.

Findings

Quantum corrections depend logarithmically on the Hubble parameter.

In modern eras, these corrections may alleviate H0 and structure-growth tensions.

Graviton corrections dominate matter field effects in supergravity-based models.

Abstract

In the context of a string-inspired running vacuum model (RVM) of cosmology with anomalies and torsion-induced axion-like fields, we discuss quantum corrections to the corresponding energy density, in approximately de Sitter eras, during which the Hubble parameter $H(t)$ varies very slowly with the cosmic time $t$. Such corrections arise either from graviton loops in the corresponding gravitational theory, or from path integration of massive quantum matter fields. They depend logarithmically on $H(t)$, in the form $H^n\, {\rm ln}(H^2)$, $n \in 2Z^+$. In the modern eras, for which the $n=2$ terns are dominant, such corrections may contribute to an alleviation of the currently observed cosmological $H_0$ and structure-growth tensions. In particular, we argue that such an effect is accomplished for a (dynamically-broken) supergravity-based RVM cosmological model. In the current de-Sitter era, for this case, rather surprisingly, the quantum graviton corrections dominate those due to matter fields, provided the scale of the primordial (pre-RVM inflation) dynamical breaking of local supersymmetry lies near the reduced Planck scale, which is a natural assumption in the context of the model.