Investigating the Electroweak Phase Transition with a Real Scalar Singlet at a Muon Collider

TL;DR

This paper explores how a 3 TeV muon collider can detect signs of a strong first-order electroweak phase transition in an extended Standard Model with a scalar singlet, aiding understanding of baryogenesis and gravitational waves.

Contribution

It provides a detailed analysis of the collider's potential to directly observe scalar particles indicative of SFOEWPT in the xSM model, considering decay modes and theoretical uncertainties.

Findings

A 3 TeV muon collider can effectively detect scalar particles related to SFOEWPT.

The study constrains the parameter space for SFOEWPT using decay mode analysis.

Collider sensitivity complements gravitational wave constraints.

Abstract

A strong first-order electroweak phase transition (SFOEWPT) is essential for explaining baryogenesis and for potentially generating observable gravitational waves. This study investigates the potential of a high-energy muon collider to examine the occurrence of SFOEWPT within the context of a Standard Model extended by a real scalar singlet (xSM). We analyzed all possible decay modes of the singlet to constrain the valid parameter space of SFOEWPT, which was extracted numerically at different renormalization scales to account for theoretical uncertainties, thereby determining the sensitivity of a muon collider to the production and decay channels of novel heavy scalar particles that emerge in the xSM. The findings demonstrate that a 3 TeV muon collider can directly examine the nature of electroweak symmetry breaking by efficiently detecting novel scalar particles associated with a first-order electroweak phase transition through jet-rich final states, thus complementing the indirect constraints from gravitational wave experiments.