HDECAY: a Program for Higgs Boson Decays in the Standard Model and its Supersymmetric Extension

TL;DR

HDECAY presents a self-contained Fortran program that computes Higgs decay widths and branching ratios in both the Standard Model and the MSSM, integrating major decay channels with current QCD and electroweak corrections. It handles threshold effects, off-shell and three-body decays, and includes SUSY decay channels when kinematically allowed, producing detailed and organized output files. The paper details the implemented decay modes, input/output structure, and test-run results, and discusses limitations and potential improvements for future versions. This tool enables precise, accessible predictions essential for interpreting Higgs searches and SUSY scenarios at current and future colliders.

Abstract

We describe the Fortran code HDECAY which calculates the decay widths and the branching ratios of the Standard Model Higgs boson, and of the neutral and charged Higgs particles of the Minimal Supersymmetric extension of the Standard Model. The program is self-contained (with all subroutines included), easy to run, fast and calculates the decay widths and branching ratios according to the current theoretical knowledge.

Figures (4)

• Figure 1: Interpolation between the full massive NLO expression (dashed line) for the $b\bar{b}$ decay width of the Standard Higgs boson and the renormalization group improved NNNLO result (dotted line). The interpolated curve is presented by the full line.
• Figure 2: Total decay width $\Gamma(H)$ in GeV and the main branching ratios $BR(H)$ of the Standard Model Higgs decay channels, using the inputs of Tab. 2.
• Figure 3: Branching ratios of the MSSM Higgs bosons $h, A (a), H (b), H^\pm (c)$ and their total decay widths $\Gamma(\Phi) (c)$, using the inputs of Tab. 2.
• Figure 3: Continued.