Probing gravitational baryogenesis phenomenon in specific modified gravity

Abstract

In this research, we investigate the phenomenon of gravitational baryogenesis and generalized gravitational baryogenesis within the framework of $f(Q,B)$ gravity where $Q$ expresses the non-metricity scalar and $B$ is the boundary term. To explore this mechanism, we utilize four distinct minimal and non-minimal $f(Q,B)$ models and analyze the evolution of the baryon to entropy ratio in relation to a scale factor in the form of a power-law ( $a={\rm Y}{t}^{\gamma }$, where ${\rm Y}$ and $\gamma$ are nonzero constants). By studying the CP-violating interaction terms ${\partial }_{\mu }(Q+B)$ and ${\partial }_{\mu }f(Q+B)$, we derive expressions for the baryon asymmetry and examine its behavior across different cosmological epochs. The results obtained from all four models demonstrate compatibility with current observational data on baryon asymmetry, suggesting that $f(Q,B)$ gravity offer a robust explanation for the matter–antimatter imbalance in the universe. Our findings reinforce the potential of this modified gravity theory to extend the understanding of baryogenesis beyond the scope of standard models, offering new insights into early universe cosmology and the mechanisms driving the generation of baryon asymmetry.