CPsuperH: a Computational Tool for Higgs Phenomenology in the Minimal Supersymmetric Standard Model with Explicit CP Violation

TL;DR

This work introduces CPsuperH, a self-contained Fortran package designed to compute the Higgs mass spectrum and decay widths in the MSSM with explicit CP violation, using RG-improved diagrammatic calculations that include dominant higher-order logs, threshold corrections, and Higgs pole-mass shifts. It provides a detailed framework for neutral and charged Higgs masses, a $3\times3$ neutral-Higgs mixing matrix $O$, and extensive Higgs couplings and decay channels, incorporating $\tan\beta$-enhanced resummations and loop-induced processes such as $\gamma\gamma$ and $gg$ decays. The program is structured for fast execution and easy extension, making it a valuable tool for phenomenological studies at Tevatron, LHC, and future linear colliders, and it remains applicable to the CP-conserving MSSM limit. The paper also discusses conventions, input/output structures, and practical usage, while outlining potential enhancements and broader implications of radiative CP violation in Higgs phenomenology, including connections to EDMs and baryogenesis.

Abstract

We provide a detailed description of the Fortran code CPsuperH, a newly--developed computational package that calculates the mass spectrum and decay widths of the neutral and charged Higgs bosons in the Minimal Supersymmetric Standard Model with explicit CP violation. The program is based on recent renormalization-group-improved diagrammatic calculations that include dominant higher--order logarithmic and threshold corrections, b-quark Yukawa-coupling resummation effects and Higgs-boson pole-mass shifts. The code CPsuperH is self--contained (with all subroutines included), is easy and fast to run, and is organized to allow further theoretical developments to be easily implemented. The fact that the masses and couplings of the charged and neutral Higgs bosons are computed at a similar high-precision level makes it an attractive tool for Tevatron, LHC and LC studies, also in the CP-conserving case.

Figures (4)

• Figure 1: The branching ratios and total decay widths of the MSSM Higgs bosons, taking into account only the decays into SM particles. All the CP phases are set to zero and $\tan\beta=1.5$ is taken. For the comparison with HDECAY, the threshold corrections are not included and we assume the 'maximal mixing' scenario: $|A_{t,b,\tau}|=\sqrt{6}M_{\rm SUSY}$ with the common SUSY scale $M_{\rm SUSY}=M_{\tilde{Q}_3}=M_{\tilde{U}_3}=M_{\tilde{D}_3} =M_{\tilde{L}_3}=M_{\tilde{E}_3}=1$ TeV and $|\mu|=100$ GeV. The results are consistent with those from the code HDECAY.
• Figure 2: The branching ratios and total decay widths of the MSSM Higgs bosons, taking into account only the decays into SM particles. All the CP phases are set to zero and $\tan\beta=4$ is taken. We assume the CPX scenario: $|M_3|=1$ TeV, $|\mu|=4M_{\rm SUSY}$ and $|A_{t,b,\tau}|=2M_{\rm SUSY}$ with the common SUSY scale $M_{\rm SUSY}=M_{\tilde{Q}_3}=M_{\tilde{U}_3}=M_{\tilde{D}_3}= M_{\tilde{L}_3}=M_{\tilde{E}_3}=0.5$ TeV.
• Figure 3: The same as in Fig. \ref{['fig:cpx0']}, but with non--trivial CP phases: $\Phi_{A_t}=\Phi_{A_b}=\Phi_{A_\tau}=\Phi_3=90^{\rm o}$.
• Figure 4: The dependence of the branching ratios of Higgs bosons into superparticles on the phase $\phi_\mu$, for $\tan\beta = 5, \, M_{H^+}^{\rm pole} = 0.3$ TeV, $M_{\tilde{Q}_3} = M_{\tilde{U}_3} = M_{\tilde{D}_3} = M_{\tilde{L}_3} = M_{\tilde{E}_3} = 0.5$ TeV, $|\mu| = 250$ GeV, $|M_1| = 50$ GeV, $|M_2| = 150$ GeV, $|M_3| = 0.5$ TeV, $|A_t| = |A_b| = |A_\tau| = 1.2$ TeV, $\Phi_2 = \Phi_3 = 0$, and $\Phi_{A_t} = \Phi_{A_b} = \Phi_{A_\tau} = - \Phi_\mu$. The left frame shows results for $H_1$ for several choices of $\Phi_1$; in this case the only contributing final state is $\tilde{\chi}_1^0 \tilde{\chi}_1^0$. The right frame shows results for the heavier Higgs bosons, where the solid (dotted) lines are for $\Phi_1 = 0 \ (180^\circ)$; in this case heavier neutralinos and charginos contribute, but no sfermions.