Gravitational mechanism for baryogenesis in the cosmological QCD phase transition

Abstract

One of the biggest puzzles in modern cosmology is the observed baryon asymmetry in the universe. In current models of baryogenesis gravity plays a secondary role, although the process is believed to have happened in the early universe, under the influence of an intense gravitational field. In the present work we resume Sakharov's original program for baryogenesis and propose a central role for gravity in the process. This is achieved through a non-minimal coupling (NMC) between the gravitational field and both the strong interaction field and the quark fields. When in action, the present mechanism leads to baryon number non-conservation and CP violation. Moreover, the NMC induces reduced effective quark masses, which favours a first order QCD phase transition. As a consequence, a baryon asymmetry can be attained in the transition from the quark epoch to the hadron epoch.

Fermion production in bouncing cosmologies

“…The functions α k (η) and β k (η) are exactly the same as the ones defined in Eq. (23). In order to see this, we must invert z using Eq.…”

“…Another possibility is to consider new different couplings between the fermionic fields and gravity (see Refs. [23,24] as examples), not only to yield an overproduction of particles on anti-particles, but also to enhance the fermionic production with respect to the standard minimal coupling case. This paper is divided as follows: in Sec.…”