Intrinsic problems of gravitational baryogenesis

TL;DR

This paper analyzes the issues in gravitational baryogenesis involving curvature-dependent modifications to gravity, revealing that such modifications lead to unstable higher-order equations and potentially distort standard cosmology.

Contribution

It demonstrates that curvature-dependent terms in gravitational baryogenesis cause fourth-order equations and instability, challenging the viability of these models.

Findings

Fourth order differential equations replace algebraic relations in modified gravity.

Instability of solutions due to higher-order equations.

Non-linear terms can stabilize but distort standard cosmology.

Abstract

Modification of gravity due to the curvature dependent term in the gravitational baryogenesis scenario is considered. It is shown that this term leads to the fourth order differential equation of motion for the curvature scalar instead of the algebraic one of General Relativity (GR). The fourth order gravitational equations are generically unstable with respect to small perturbations. Non-linear in curvature terms may stabilize the solution but the magnitude of the stabilized curvature scalar would be much larger than that dictated by GR, so the standard cosmology would be strongly distorted.