BSMPT v2 a tool for the electroweak phase transition and the baryon asymmetry of the universe in extended Higgs Sectors

Abstract

We present the C++ code BSMPT v2 which is an extension of the previous code BSMPT for the calculation of the strength of the electroweak phase transition in extended Higgs sectors. The new version BSMPT v2 includes the features of BSMPT and extends the already implemented models (the 2-Higgs-Doublet model (2HDM) in its CP-conserving and CP-violating versions and the Next-to-2HDM) by the Complex Singlet Extension of the Standard Model (CxSM). The major upgrade is the implementation of the computation of the baryon asymmetry of the Universe for the CP-violating 2HDM (C2HDM), which is performed in two different approximations. These changes and further smaller modifications are described in this manual. Additionally, a detailed explanation of the procedure for the implementation of new models is given, which has also changed with respect to the previous version. Program summaryProgram Title:BSMPTCPC Library link to program files:https://doi.org/10.17632/sjtp7bb33t.1Licensing provisions: GPL-3.0 LicenseProgramming Language:C++14Nature of problem: Non-minimal extended Higgs sector models provide non-trivial vacuum structures which allow for a strong first order electroweak phase transition. Such a phase transition is one of the three Sakharov conditions that are required for a dynamical generation of the observed baryon asymmetry of the universe (BAU) through an electroweak phase transition. The actual calculation of the electroweak baryogenesis requires the solution of the quantum transport equation system describing the non-thermal equilibrium state of the early universe during the phase transition. BSMPT v2 provides a numerical tool to investigate the vacuum structure of the one-loop effective potential at finite temperature including thermal masses, for an arbitrary extended Higgs sector. It allows for the computation of the strength of the electroweak phase transition for the implemented models. For the CP-violating 2HDM (C2HDM) also the generated BAU is calculated. For the latter task BSMPT v2 has two different approaches implemented for the formulation of the quantum transport equations, given by the FH approach based on the semi-classical force and the vacuum expectation value insertion method VIA.Solution Method: Numerical minimization of the one-loop effective potential including thermal masses, at finite temperature with three different numerical minimizers, GSL, cmaes and NLopt, in order to determine the relevant parameters required for the phase transition dynamics at the critical temperature and the criticial field configuration. Furthermore, with the updated version BSMPT v2 it is possible to numerically solve for the C2HDM the system of coupled differential transport equations and calculate the BAU for this model.Additional comments including restrictions and unusual features: The BSM extensions are restricted to the Higgs sectors. New gauge bosons and fermions would require an adaption in the thermal corrections of the one-loop potential, which is not implemented in BSMPT v2. At present, the BAU is only calculated for the C2HDM. In the computation of the BAU the wall velocity is an input parameter and assumed to be small, for the VEV configuration a kink profile is assumed, the nucleation temperature is approximated by the critical temperature.