Pair Production of a 125 GeV Higgs Boson in MSSM and NMSSM at the LHC

TL;DR

This study investigates Higgs pair production for a SM-like 125 GeV Higgs within the MSSM and NMSSM under current LHC constraints. By scanning SUSY parameter spaces with experimental bounds and computing the hh cross section primarily via gluon fusion (with subleading bb→hh contributions), the authors quantify how stop/squark loops and Higgs mixing alter the rate. They find gluon fusion can enhance the SM hh rate by up to about 10×, with realistic TeV-scale stops still providing sizable gains; the most favored regions yield approximately 1.45× enhancement in the MSSM and a NMSSM range of 0.7–2.4×, with NMSSM1 typically larger than the NMSSM2 case. These results demonstrate that Higgs self-coupling-ssi sensitive Higgs pair production can serve as a meaningful test of SUSY scenarios at the LHC.

Abstract

In light of the recent LHC Higgs search data, we investigate the pair production of a SM-like Higgs boson around 125 GeV in the MSSM and NMSSM. We first scan the parameter space of each model by considering various experimental constraints, and then calculate the Higgs pair production rate in the allowed parameter space. We find that in most cases the dominant contribution to the Higgs pair production comes from the gluon fusion process and the production rate can be greatly enhanced, maximally 10 times larger than the SM prediction (even for a TeV-scale stop the production rate can still be enhanced by a factor of 1.3). We also calculate the chi-square value with the current Higgs data and find that in the most favored parameter region the production rate is enhanced by a factor of 1.45 in the MSSM, while in the NMSSM the production rate can be enhanced or suppressed (σ_{SUSY}/σ_{SM} varies from 0.7 to 2.4).

Figures (5)

• Figure 1: Feynman diagrams for the pair production of the SM-like Higgs boson via gluon fusion in the MSSM and NMSSM with $H_I$ denoting a CP-even Higgs ($I=1,2$ for the MSSM and $I=1,2,3$ for the NMSSM) and $\tilde{q}_{i,j}$ ($i,j=1,2$) for a squark. The diagrams with initial gluons or final Higgs bosons interchanged are not shown here. For the quarks and squarks we only consider the third generation due to their large Yukawa couplings.
• Figure 2: Feynman diagrams for the parton process $b\bar{b}\to hh$ in the MSSM and NMSSM.
• Figure 3: The scatter plots of the surviving samples, showing $\sigma_{SUSY}/\sigma_{SM}$ versus the SM-like Higgs boson mass. The plus '+' (blue) denote the results with only the gluon fusion contribution, while the circles '$\circ$' (pink) are for the total results.
• Figure 4: Same as Fig \ref{['fig-ratio-mh']}, but showing $A_t/m_{\tilde{t}_1}$ versus $m_{\tilde{t}_1}$. The samples are classified according to the value of $R=\sigma_{SUSY}(gg\to hh)/\sigma_{SM}(gg\to hh)$ with $\sigma$ denoting the hadronic cross section via $gg\to hh$.
• Figure 5: Same as Fig. \ref{['fig-ratio-mh']}, but showing $\sigma_{SUSY}/\sigma_{SM}$ versus $\chi^2$. Here only the samples satisfying 125 GeV $\le m_h \leq 126$ GeV are plotted.