Thermodynamics of a two-step electroweak phase transition

TL;DR

This paper investigates the thermodynamics of a two-step electroweak phase transition in a triplet-extended Standard Model using nonperturbative lattice simulations, revealing a narrow parameter space with first-order transitions and discrepancies with perturbative methods.

Contribution

It provides the first nonperturbative lattice analysis of a two-step electroweak phase transition in a triplet extension, highlighting the limitations of perturbative calculations.

Findings

Two-step transition occurs in a narrow parameter space.

Second transition is always first order.

Significant discrepancies with perturbative results.

Abstract

New field content beyond that of the Standard Model of particle physics can alter the thermal history of electroweak symmetry breaking in the early universe. In particular, the symmetry breaking may have occurred through a sequence of successive phase transitions. We study the thermodynamics of such scenario in a real triplet extension of the Standard Model, using nonperturbative lattice simulations. Two-step electroweak phase transition is found to occur in a narrow region of allowed parameter space with the second transition always being first order. The first transition into the phase of non-vanishing triplet vacuum expectation value is first order in a non-negligible portion of the two-step parameter space. A comparison with 2-loop perturbative calculation is provided and significant discrepancies with the nonperturbative results are identified.