Reshuffled Strongly Interacting Massive Particle Dark Matter

TL;DR

This paper introduces the reshuffled SIMP (rSIMP) dark matter scenario, analyzing how an induced 2→2 process affects relic abundance and mass degeneracy, with implications for dark matter self-interactions.

Contribution

It presents a novel reshuffled SIMP model incorporating 2→2 processes, providing a detailed numerical analysis of relic abundance and mass degeneracy.

Findings

Masses of rSIMP DM must be nearly degenerate.

Reshuffled mechanism is sensitive to DM self-interaction cross section.

Effective operators connect dark and visible sectors via vector portal.

Abstract

In this work, we reanalyze the multi-component strongly interacting massive particle (mSIMP) scenario using an effective operator approach. As in the single-component SIMP case, the total relic abundance of mSIMP dark matter (DM) is determined by the coupling strengths of $3 \to 2$ processes achieved by a five-point effective operator. Intriguingly, we notice that there is an irreducible $2 \to 2$ process induced by the corresponding five-point interaction in the dark sector, which would reshuffle the mass densities of SIMP DM after the chemical freeze-out. We dub this DM scenario as reshuffled SIMP ($r$SIMP). Given this observation, we then numerically solve the coupled Boltzmann equations including the $3 \to 2$ and $2 \to 2$ processes to get the correct yields of $r$SIMP DM. It turns out that the masses of $r$SIMP DM must be nearly degenerate for them to contribute sizable abundances. On the other hand, we also introduce effective operators to bridge the dark sector and visible sector via a vector portal coupling. Notably, we find that the reshuffled mechanism in the $r$SIMP scenario is sensitive to the size of the DM self-interacting cross section.