The Supersymmetric R-Parity Violating Dine-Fischler-Srednicki-Zhitnitsky Axion Model

TL;DR

This paper introduces a supersymmetric model with R-parity violation incorporating an axion as a dark matter candidate, analyzing its cosmological viability, decay modes, and potential explanations for astrophysical signals.

Contribution

It presents a complete R-parity violating supersymmetric axion model with detailed analysis of axino decay modes and cosmological implications, including constraints from astrophysical observations.

Findings

Axino can be a warm dark matter candidate with keV mass.

Astrophysical constraints limit certain R-parity violating couplings.

Decays of relic axinos could explain the 3.5 keV X-ray line.

Abstract

We propose a complete R-parity violating supersymmetric model with baryon triality that contains a Dine-Fischler-Srednicki-Zhitnitsky axion chiral superfield. We parametrize supersymmetry breaking with soft terms, and determine under which conditions the model is cosmologically viable. As expected we always find a region of parameter space in which the axion is a cold dark matter candidate. The mass of the axino, the fermionic partner of the axion, is controlled by a Yukawa coupling. When heavy [${\mathcal O}$(TeV)], the axino decays early and poses no cosmological problems. When light [$\mathcal{O}$(keV)] it can be long lived and a warm dark matter candidate. We concentrate on the latter case and study in detail the decay modes of the axino. We find that constraints from astrophysical X- and gamma rays on the decay into photon and neutrino can set new bounds on some trilinear supersymmetric R-parity violating Yukawa couplings. In some corners of the parameter space the decays of a relic axino can also explain a putative 3.5 keV line.