Communication with SIMP dark mesons via [formula omitted]-portal

Hyun Min Lee,Min-Seok Seo

doi:10.1016/j.physletb.2015.07.013

Abstract

We consider a consistent extension of the SIMP models with dark mesons by including a dark U(1)D gauge symmetry. Dark matter density is determined by a thermal freeze-out of the 3→2 self-annihilation process, thanks to the Wess–Zumino–Witten term. In the presence of a gauge kinetic mixing between the dark photon and the SM hypercharge gauge boson, dark mesons can undergo a sufficient scattering off the Standard Model particles and keep in kinetic equilibrium until freeze-out in this SIMP scenario. Taking the SU(Nf)×SU(Nf)/SU(Nf) flavor symmetry under the SU(Nc) confining group, we show how much complementary the SIMP constraints on the parameters of the dark photon are for current experimental searches for dark photon.

Highlights

Various evidences of dark matter (DM) imply that fundamental particles and interactions need to be extended beyond the Standard Model (SM) [1]
The Strongly Interacting Massive Particle (SIMP) scenario requires the interaction between dark and SM sectors in the form of scattering for dark matter to be in kinetic equilibrium with the SM particles, without altering the structure formation [8]
We have considered an extension of the models with SIMP dark mesons by including a dark local U(1)D symmetry under which dark quarks are vector-like

Summary

Introduction

Various evidences of dark matter (DM) imply that fundamental particles and interactions need to be extended beyond the Standard Model (SM) [1]. Since WIMP mass is of order weak scale for the effective coupling of αeff ∼ O(10−2), ‘WIMP miracle’ has been the mainstream for thermal DM studies, corroborating the expectation of finding new physics at the weak scale in the solutions for gauge hierarchy problem Another interesting proposal for thermal (pseudo-)scalar DM has been recently made under the name of Strongly Interacting Massive Particle (SIMP) [2,3,4], explaining DM relic density through the freeze-out of 3 → 2 self-annihilation. The SIMP scenario requires the interaction between dark and SM sectors in the form of scattering for dark matter to be in kinetic equilibrium with the SM particles, without altering the structure formation [8] Since such an inter-sector interaction leads to the DM annihilation into SM particles, the inter-sector interaction strength is bounded from above for the dominance of 3 → 2 self-annihilation, if combined, resulting in nDM σ v ann < n2DM σ v2 3→2 < nSM σ v scatt, at the freeze-out temperature.

SIMP dark mesons and the WZW term

Findings

Conclusion