Gravitational baryogenesis in running vacuum models

Abstract

We study the gravitational baryogenesis mechanism for generating baryon asymmetry in the context of running vacuum models. Regardless if these models can produce a viable cosmological evolution, we demonstrate that they produce a non-zero baryon-to-entropy ratio even if the universe is filled with conformal matter. This is a sound difference between the running vacuum gravitational baryogenesis and the Einstein-Hilbert one, since in the latter case, the predicted baryon-to-entropy ratio is zero. We consider two well known and most used running vacuum models and show that the resulting baryon-to-entropy ratio is compatible with the observational data. Moreover, we also show that the mechanism of gravitational baryogenesis may constrain the running vacuum models. 95.36.+x, 95.35.+d * Electronic address: v.k.oikonomou1979@gmail.com † Electronic address: span@iiserkol.ac.in ‡ Electronic address: rafadcnunes@gmail.com 1 However, it deserves to be mentioned that the theory of gravitational modifications has also been found to explain the late time accelerated expansion without any need of dark energy [2][3][4][5][6][7][8][9][10][11].

Matter–antimatter asymmetry induced by a running vacuum coupling

“…It also alleviates the cosmic coincidence and problems, and, last but not least, we have found the its decay products, through the derivative coupling with the (t) term given in (4), is also capable of generating the observed baryon asymmetry. It is worth noticing that the new mechanism proposed here is different from spontaneous baryogenesis as discussed by several authors [22][23][24][25], as well as from gravitationally induced B-asymmetry powered by the Ricci scalar [26,33,40], a Gauss-Bonnet term [41] or other higher order curvature invariants. Probably, the closest approach is the gravitational baryogenesis driven by the Ricci scalar in the presence of a running vacuum [40].…”

Dynamics of Einstein–Aether scalar field cosmology

“…which looks like the particle creation, bulk viscosity or varying vacuum theories [60][61][62][63][64][65][66]. Positive values of B φ indicate particle annihilation while negative values of B φ indicate particle creation.…”

Exact solutions, finite time singularities and non-singular universe models from a variety of Λ(t) cosmologies

“…This theory became more popular at recent time when the rigid cosmological constant was questioned by recent observations. Thus so far, along with other alternative cosmological models, the theory of Λ(t) gained much attention in the scientific community [10,11,12,13,14,15,16,17,18,19,20,21,22] (also see [31]). A quantum field theoretic development in this direction [29,30,31,32] fueled such investigations and inspired many cosmologists to extract information out of the phenomenological Λ(t) models.…”

“…However, the field equations for this theory do not follow from any covariant action. Nevertheless, in the last several years, a series of works towards this direction has been performed with several interesting results [10,11,12,13,14,15,16,17,18,19,20,21,22] and very recently another series of works [23,24,25,26,27,28] showing that the current astronomical data from different independent sources favor the Λ(t) class of models in compared to the concordance ΛCDM cosmology. In view of the observational data, Λ(t) models could be an emerging class of cosmological models, for instance a suitable choice of some models belonging to this class can describe the entire cosmic histroy [16,17,18].…”