Collider phenomenology of Hidden Valley mediators of spin 0 or 1/2 with semivisible jets

TL;DR

This paper explores the collider signatures of spin 0 or 1/2 mediators connecting Standard Model particles with a Hidden Valley sector, focusing on semivisible jets and how current searches can be improved to detect them.

Contribution

It provides a classification of collider phenomenology for mediators with mixed gauge charges and proposes modifications to search strategies for better detection.

Findings

Large regions of parameter space are already excluded.

Some scenarios remain unconstrained by current searches.

Modifying search strategies can improve detection of semivisible jets.

Abstract

Many models of Beyond the Standard Model physics contain particles that are charged under both Standard Model and Hidden Valley gauge groups, yet very little effort has been put into establishing their experimental signatures. We provide a general overview of the collider phenomenology of spin 0 or 1/2 mediators with non-trivial gauge numbers under both the Standard Model and a single new confining group. Due to the possibility of many unconventional signatures, the focus is on direct production with semivisible jets. For the mediators to be able to decay, a global $U(1)$ symmetry must be broken. This is best done by introducing a set of operators explicitly violating this symmetry. We find that there is only a finite number of such renormalizable operators and that the phenomenology can be classified into five distinct categories. We show that large regions of the parameter space are already excluded, while others are unconstrained by current search strategies. We also discuss how searches could be modified to better probe these unconstrained regions by exploiting special properties of semivisible jets.