Axino LSP Baryogenesis and Dark Matter

TL;DR

This paper proposes a novel baryogenesis mechanism involving the decay of the axino LSP with baryonic R-parity violation, linking it to dark matter composition and setting constraints on superpartner masses.

Contribution

It introduces a new baryogenesis scenario with specific predictions for supersymmetric particle masses and explores its implications for axion and gravitino dark matter.

Findings

Upper squark mass limits between 15 and 130 TeV

Both axion and gravitino can account for dark matter

Reheating temperature constraints linked to PQ scale

Abstract

We discuss a new mechanism for baryogenesis, in which the baryon asymmetry is generated by the lightest particle in another sector, for example the supersymmetric particle (LSP), decaying to quarks via baryonic-number-violating interactions. As a specific example, we use a supersymmetric axion model with an axino LSP and baryonic $R$-parity violation. This scenario predicts large $R$-parity violation for the stop, and an upper limit on the squark masses between {15 and 130 TeV}, for different choices of the Peccei-Quinn scale and the soft $X_t$ terms. We discuss the implications for the nature of dark matter in light of the axino baryogenesis mechanism, and find that both the axion and a metastable gravitino can provide the correct dark matter density. In the axion dark matter scenario, the initial misalignment angle is restricted to be ${\cal O}(1)$. On the other hand, the reheating temperature is linked to the PQ scale and should be higher than $10^4-10^5$ GeV in the gravitino dark matter scenario.