Baryogenesis in $f(P)$ Gravity

TL;DR

This paper explores gravitational baryogenesis within $f(P)$ gravity, analyzing how modifications involving the cubic term $P$ influence baryon asymmetry and identifying parameter ranges that match observational data.

Contribution

It introduces a novel analysis of baryogenesis in $f(P)$ gravity, considering both linear and generalized CP-violating interactions, expanding understanding of modified gravity's role in baryon asymmetry.

Findings

Baryon-to-entropy ratio depends on derivatives of $R$ and $P$.

Rational values of parameters produce ratios compatible with observations.

Generalized interaction proportional to $f(P)$ affects the baryon asymmetry expression.

Abstract

In this work, we investigate gravitational baryogenesis in the framework of $f(P)$ gravity to understand the applicability of this class of modified gravity in addressing the baryon asymmetry of the Universe. For the analysis, we set $f(P) = \alpha P$ where $\alpha$ is the model parameter. We found that in $f(P)$ gravity, the CP-violating interaction acquires a modification through the addition of the nontopological cubic term $P$ in addition to the Ricci scalar $R$ and the mathematical expression of the baryon-to-entropy ratio depends not only on the time derivative of $R$ but also the time derivative of $P$. Additionally, we also investigate the consequences of a more complete and generalized CP-violating interaction proportional to $f(P)$ instead of $P$ in addressing the baryon asymmetry of the Universe. For this type of interaction, we report that the baryon-to-entropy ratio is proportional to $\dot{R}$, $\dot{P}$ and $f^{'}(P)$. We report that for both of these cases, rational values of $\alpha$ and $\chi$ generate acceptable baryon-to-entropy ratios compatible with observations.