HDECAY: Twenty++ Years After

TL;DR

HDECAY is a comprehensive program for calculating Higgs boson decay properties across various models, incorporating higher-order effects and updates over twenty years.

Contribution

This paper presents an updated overview of HDECAY, including new developments and features added since its initial release.

Findings

Includes decay widths and branching ratios for multiple Higgs models

Incorporates radiative corrections and multi-body decay channels

Supports extensions like the two-Higgs doublet model and MSSM

Abstract

The program HDECAY determines the partial decay widths and branching ratios of the Higgs bosons within the Standard Model with three and four generations of fermions, including the case when the Higgs couplings are rescaled, a general two--Higgs doublet model where the Higgs sector is extended and incorporates five physical states and its most studied incarnation, the minimal supersymmetric Standard Model (MSSM). The program addresses all decay channels including the dominant higher-order effects such as radiative corrections and multi-body channels. Since the first launch of the program, more than twenty years ago, important aspects and new ingredients have been incorporated. In this update of the program description, some of the developments are summarized while others are discussed in some detail.