A number of challenges to the standard Λ CDM model have been emerging during the past
few years as the accuracy of cosmological observations improves. In this review we discuss …

We present a brief, and to a great extent, pedagogical, review on renormalization in curved
spacetime and some recent results on the derivation and better understanding of quantum …

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 …

Abstract The\(\Lambda\)-term in Einstein's equations is a fundamental building block of the
'concordance'\(\Lambda\) CDM model of cosmology. Even though the model is not free of …

Despite the many outstanding cosmological observations leading to a strong evidence for a
non-vanishing cosmological constant (CC) term Λ in the gravitational field equations, the …

We use big bang nucleosynthesis (BBN) data in order to impose constraints on higher-order
modified gravity and, in particular, on (i) f (G) Gauss-Bonnet gravity and f (P) cubic gravities …

We investigate the properties of the FLRW flat cosmological models in which the vacuum
energy density evolves with time, Λ (t). Using different versions of the Λ (t) model, namely …

In previous works, we have derived a Running Vacuum Model (RVM) for a string Universe,
which provides an effective description of the evolution of 4-dimensional string-inspired …

We present a model for the Universe in which quantum anomalies are argued to play an
important dual role: they are responsible for generating matter-antimatter asymmetry in the …

Despite the many efforts, our theoretical understanding of the ultimate nature of the dark
energy component of the universe still lags well behind the astounding experimental …