NMHDECAY: A Fortran Code for the Higgs Masses, Couplings and Decay Widths in the NMSSM

TL;DR

NMHDECAY delivers a self-contained Fortran framework to compute the NMSSM Higgs sector, including masses, mixings and decays, from parameters defined at the SUSY-breaking scale. It combines full one-loop and leading two-loop radiative corrections with RG-improved running, uses an on-shell scheme for decay widths, and enforces LEP-based phenomenological constraints via LEPCON data. The package supports SLHA-like input/output (with NMSSM extensions) and includes a scanning mode to explore parameter space and detect novel decays such as $h_1\to a_1a_1$, highlighting regions with distinctive LHC phenomenology. Overall, NMHDECAY enables precise NMSSM Higgs phenomenology studies, including unconventional decay channels and interplay with experimental bounds, aiding both theory and collider analyses.

Abstract

The Fortran code NMHDECAY computes the masses, couplings and decay widths of all Higgs bosons of the NMSSM in terms of its parameters at the electroweak (SUSY breaking) scale: the Yukawa couplings lambda and kappa, the soft trilinear terms A_lambda and A_kappa, and tan(beta) and mu_eff = lambda*<S>. The computation of the spectrum includes leading two loop terms, electroweak corrections and propagator corrections. The computation of the decay widths is carried out as in HDECAY, but (for the moment) without three body decays. Each point in parameter space is checked against negative Higgs bosons searches at LEP, including unconventional channels relevant for the NMSSM. One version of the program uses generalized SLHA conventions for input and output.

Figures (3)

• Figure 1: Branching ratios of $h_1$ as a function of $A_{\lambda}$ for $\lambda=\kappa= 0.3$, $\tan\beta=5$, $\mu_\mathrm{eff} = 180~{\rm GeV}$, $A_{\kappa}$ = 0, $m_\mathrm{squark} =1~{\rm TeV}$, and $A_t=1.5~{\rm TeV}$.
• Figure 3: Branching ratios of $h_1$ as a function of $A_{\kappa}$ for $\lambda=0.5$, $\kappa=-0.15$, $\tan\beta$ = 3.5, $\mu_\mathrm{eff}$ = 200 GeV, $A_{\lambda}=780~{\rm GeV}$, $m_\mathrm{squark} =1~{\rm TeV}$, and $A_t=1.5~{\rm TeV}$.
• Figure 5: $m_{h_1}$ and $m_{h_1}$ as a function of $A_{\kappa}$ for the same parameters as in fig. \ref{['nmhfig3']}.