Gravitational Baryogenesis from Entropy Production and Parity Violation: A Unified Framework

TL;DR

This paper proposes a unified gravitational baryogenesis framework combining entropy production and CP violation via a gravitational theta term, predicting baryon asymmetry and gravitational wave polarization potentially testable by future detectors.

Contribution

It introduces a novel combined mechanism for baryogenesis that links entropy production, CP violation, and gravitational wave polarization, with a minimal UV completion and testable predictions.

Findings

Quantifies entropy-clock evasion of adiabatic suppression using a universal transfer function.

Provides an analytic expression for gravitational wave polarization in Loop Quantum Cosmology bounces.

Predicts baryon asymmetry dependence on reheating temperature, theta angle, and entropy history.

Abstract

We present a unified framework for gravitational baryogenesis combining two mechanisms: (i) an entropy-clock source that generates a sign-definite baryon chemical potential mu_B proportional to d ln S/dt during irreversible entropy production, and (ii) CP violation from a gravitational theta term theta R Rtilde analogous to the QCD vacuum angle. The entropy-clock evades adiabatic cancellation that suppresses purely oscillatory chemical potentials under smooth freeze-out; we quantify this with a universal low-pass transfer function F(x)=1/sqrt(1+x^2), where x=omega*tau_off. A minimal UV completion via a dilaton coupled to the conformal anomaly yields the entropy-clock coupling with decay constant f_sigma ~ 10^17-10^18 GeV. The theta term provides CP violation through interference between topologically distinct gravitational configurations; we estimate an instanton suppression factor kappa_inst ~ 10^-2-10^-1. The combined mechanism predicts Y_B ~ c*kappa*Pi_eff*epsilon_eff, linking the baryon asymmetry to the reheating temperature, the theta angle, and the entropy-production history. For Loop Quantum Cosmology bounces we derive an analytic expression for the circular polarization of the stochastic gravitational-wave background, with |Pi| ~ pi*|theta| for horizon-crossing modes, potentially testable by future space-based detectors.