In the realm of the Hubble tension—a review of solutions

E Di Valentino, O Mena, S Pan, L Visinelli… - … and Quantum Gravity, 2021 - iopscience.iop.org
The simplest ΛCDM model provides a good fit to a large span of cosmological data but
harbors large areas of phenomenology and ignorance. With the improvement of the number …

The cosmological constant problem and running vacuum in the expanding universe

J Sola Peracaula - … Transactions of the Royal Society A, 2022 - royalsocietypublishing.org
It is well known that quantum field theory (QFT) induces a huge value of the cosmological
constant (CC), Λ, which is outrageously inconsistent with cosmological observations. We …

The case for a positive cosmological Λ-term

V Sahni, A Starobinsky - International Journal of Modern Physics D, 2000 - World Scientific
Recent observations of Type 1a supernovae indicating an accelerating universe have once
more drawn attention to the possible existence, at the present epoch, of a small positive Λ …

Cosmological constant and vacuum energy: old and new ideas

J Sola - Journal of Physics: Conference Series, 2013 - iopscience.iop.org
The cosmological constant (CC) term in Einstein's equations, Λ, was first associated to the
idea of vacuum energy density. Notwithstanding, it is well-known that there is a huge, in fact …

The cosmon model for an asymptotically vanishing time-dependent cosmological``constant''

C Wetterich - arXiv preprint hep-th/9408025, 1994 - arxiv.org
We investigate the coupled system of gravity and a scalar with exponential potential. The
energy momentum tensor of the scalar field induces a time-dependent cosmological`` …

Bouncing cosmologies

M Novello, SEP Bergliaffa - Physics reports, 2008 - Elsevier
We review the general features of nonsingular universes (ie those that go from an era of
accelerated collapse to an expanding era without displaying a singularity) as well as cyclic …

Indications of a late-time interaction in the dark sector

V Salvatelli, N Said, M Bruni, A Melchiorri, D Wands - Physical Review Letters, 2014 - APS
We show that a general late-time interaction between cold dark matter and vacuum energy
is favored by current cosmological data sets. We characterize the strength of the coupling by …

Running Vacuum in the Universe: Phenomenological Status in Light of the Latest Observations, and Its Impact on the σ8 and H0 Tensions

J Solà Peracaula, A Gómez-Valent, J de Cruz Pérez… - Universe, 2023 - mdpi.com
A substantial body of phenomenological and theoretical work over the last few years
strengthens the possibility that the vacuum energy density (VED) of the universe is …

Evolution of the scale factor with a variable cosmological term

JM Overduin, FI Cooperstock - Physical Review D, 1998 - APS
The evolution of the scale factor a (t) in Friedmann models (those with zero pressure and a
constant cosmological term Λ) is well understood, and elegantly summarized in the review of …

First evidence of running cosmic vacuum: challenging the concordance model

J Solà, A Gómez-Valent… - The Astrophysical …, 2017 - iopscience.iop.org
Despite the fact that a rigid ${\rm {\Lambda}} $-term is a fundamental building block of the
concordance ΛCDM model, we show that a large class of cosmological scenarios with …