f(T,Θ) gravity and generalized gravitational baryogenesis

Abstract

Where is the anti-matter in our universe? This is the most significant open problem of the modern era. This paper is devoted to the study of cosmological impact of gravitational baryogenesis and its generalized case driven by [Davoudiasl et al., Phys. Rev. Lett. 93, 201301 (2004)]. In this class of baryogenesis, the Ricci scalar [Formula: see text] is derivatively coupled to the baryon current [Formula: see text] as [Formula: see text]. We examine the imbalance of baryon and anti-baryon of the universe in the context of [Formula: see text] gravity, where [Formula: see text] and [Formula: see text] are the torsion scalar and the trace of the energy–momentum tensor, respectively. We assume two [Formula: see text] models in which the first one contains the sum of second-order torsion tensors and the trace of energy–momentum tensor while the second one is the product of these terms. For all cases, we find the ratio of baryon number to entropy by considering the power-law scale factor. Finally, we compare our results with the observational value of baryon-number-density-to-entropy ratio. The baryon-to-entropy ratio against the first model lies in the range [Formula: see text] while for the second model it contains [Formula: see text]. For generalized case of gravitational baryogenesis, we also obtain results that are compatible with the observation limit.