Dark matter in Hidden Valley models with stable and unstable light dark mesons

TL;DR

This paper explores Hidden Valley models with both stable and unstable dark mesons, analyzing their potential to produce correct dark matter relic abundance and unique collider signatures like displaced vertices and jets.

Contribution

It maps the parameter space of such models, demonstrating how stable and unstable dark mesons can account for dark matter and produce distinctive collider signals.

Findings

Bounds from detection experiments can be avoided in most parameter space.

Relic density is mainly set by stable mesons annihilating to unstable ones.

Collider signatures include displaced vertices and emerging jets.

Abstract

It is a distinct possibility that a Hidden Valley sector would have a spectrum of light particles consisting of both stable and unstable dark mesons. The simultaneous presence of these two types of particles can lead to novel mechanisms for generating the correct dark matter relic abundance, which in turn can reflect themselves into new exotic signatures at colliders. We study the viability of such sectors for various Hidden Valley models and map the valid parameter space to possible collider signatures. Mediators studied include various scalar bifundamentals and a heavy $Z'$. It is shown that in general bounds from direct and indirect detection can easily be avoided. In most of the allowed parameter space, the relic density is determined by stable mesons annihilating to unstable ones which in turn decay quickly to Standard Model particles. Dark mesons that decay mainly to heavier Standard Model fermions allow for more valid parameter space, though dark mesons are still allowed to decay exclusively to some of the lighter fermions. Possible exotic collider signatures include displaced vertices, emerging jets and semivisible jets.