A Real Triplet-Singlet Extended Standard Model: Dark Matter and Collider Phenomenology

TL;DR

This paper explores an extended Standard Model with a triplet and singlet scalar, analyzing its implications for dark matter, collider signals, electroweak phase transitions, and potential gravitational wave signatures.

Contribution

It introduces a model with a triplet and singlet scalar charged under a Z2 symmetry, showing its viability for dark matter and altered collider phenomenology.

Findings

The model can produce the observed dark matter density.

Lower bounds on triplet mass are reduced compared to minimal models.

Permitted lower triplet masses are relevant for electroweak baryogenesis and gravitational waves.

Abstract

We examine the collider and dark matter phenomenology of the Standard Model extended by a hypercharge-zero SU(2) triplet scalar and gauge singlet scalar. In particular, we study the scenario where the singlet and triplet are both charged under a single $\mathbb{Z}_2$ symmetry. We find that such an extension is capable of generating the observed dark matter density, while also modifying the collider phenomenology such that the lower bound on the mass of the triplet is smaller than in minimal triplet scalar extensions to the Standard Model. A high triplet mass is in tension with the parameter space that leads to novel electroweak phase transitions in the early universe. Therefore, the lower triplet masses that are permitted in this extended model are of particular importance for the prospects of successful electroweak baryogenesis and the generation of gravitational waves from early universe phase transitions.