17–18 Sept 2026
Lund University, Physics Department
Europe/Stockholm timezone

Exploring phase transitions and gravitational waves in the conformal two-Higgs-doublet model (C2HDM).

17 Sept 2026, 16:00
15m
A-salen (L317) (Lund University, Physics Department)

A-salen (L317)

Lund University, Physics Department

Sölvegatan 14, Lund

Speaker

Mårten Bertenstam (Lund University)

Description

The mechanism behind the observed baryon asymmetry in the Universe remains an open problem that motivates the search for physics beyond the Standard Model. Indeed, within the Standard Model, the smooth crossover electroweak phase transition does not provide the required departure from thermal equilibrium, nor is there a sufficient amount of CP-violation.

In this talk, I will present our ongoing work with a model that seeks to address these shortcomings. This is a two-Higgs-doublet model with classical scale invariance (hence conformal at the classical level) and (potential) explicit CP-violation.

We explore the parameter space of the model and restrict ourselves to viable scenarios constrained by collider data. Using dimensional reduction, we construct the effective potential, and explore the phase structure and the phase transitions. For the strongly first-order ones, we also calculate the contribution to the stochastic gravitational wave background, sourced by the energy released in the transition. Such a signal could potentially be observed by future space-based gravitational-wave detectors, and thereby provide insight into the nature of phase transitions in the early Universe.

Authors

Hanxiao Pu Johan Rathsman (Lund University) Mårten Bertenstam (Lund University) Roman Pasechnik (Lund university)

Presentation materials