Matter\u2013antimatter asymmetry induced by a running vacuum coupling

J A S Lima,D Singleton

doi:10.1140/epjc/s10052-017-5429-x

Abstract

We show that a CP-violating interaction induced by a derivative coupling between the running vacuum and a non-conserving baryon current may dynamically break CPT and trigger baryogenesis through an effective chemical potential. By assuming a non-singular class of running vacuum cosmologies which provides a complete cosmic history (from an early inflationary de Sitter stage to the present day quasi-de Sitter acceleration), it is found that an acceptable baryon asymmetry is generated for many different choices of the model parameters. It is interesting that the same ingredient (running vacuum energy density) addresses several open cosmological questions/problems: avoids the initial singularity, provides a smooth exit for primordial inflation, alleviates both the coincidence and the cosmological constant problems, and, finally, is also capable of explaining the generation of matter-antimatter asymmetry in the very early Universe.

Highlights

There is a growing body of work on running vacuum cosmologies or an effective dynamical -term [1,2,3,4,5,6]. These models are motivated by the cosmological constant problem (CCP)—the absence of a satisfactory mechanism whereby the vacuum energy density from all fields can be canceled by the fixed cosmological constant
We do not know how the current, extremely small value of the effective vacuum energy density can be predicted from first principles
The question arises as to what is the total expression of E? The vacuum state of all existing fields can be represented by an energymomentum tensor (EMT) which reflects the Lorentz invariance of its energy density and pressure

Summary

Introduction

There is a growing body of work on running vacuum cosmologies or an effective dynamical -term [1,2,3,4,5,6] These models are motivated by the cosmological constant problem (CCP)—the absence of a satisfactory mechanism whereby the vacuum energy density from all fields can be canceled (or almost canceled) by the fixed cosmological constant. Given the possibility of a running vacuum cosmology, it is essential to investigate how the baryogenesis problem, i.e. the observed matter-(anti)matter asymmetry, can be handled in this context This old problem becomes more intriguing in the light of the novel running vacuum scenario where the space-time emerges from a pure non-singular de Sitter stage smoothly evolving into radiation, matter and 0CDM, thereby avoiding the initial singularity and providing a complete description of the expansion history [17,18]. The predicted matter– (anti)matter asymmetry is in good agreement with the observations for many different choices of the relevant cosmic energy scales

Running vacuum baryogenesis

Running vacuum cosmology

Baryogenesis constraints

Final remarks