Constraining the light Higgs bosons in the GNMSSM with recent Higgs data

TL;DR

This work analyzes exotic decays of the 125 GeV SM-like Higgs into pairs of light Higgs bosons within the GNMSSM to probe beyond-SM scenarios and assess implications for a strong electroweak phase transition and baryogenesis. It employs a MultiNest parameter scan constrained by HiggsSignals, HiggsBounds, and ATLAS searches across two SM-like assignment cases ($h_1=h_{ m SM}$ or $h_2=h_{ m SM}$), showing HiggsBounds typically yields the strongest exclusions while HiggsSignals provides complementary indirect constraints, especially in the $h_2$-SM case. The analysis requires the observed Higgs to be highly SM-like with $V_h^{ m SM} earrow 0.93$ and limited singlet mixing $V_h^{ m S} earrow 0.32$, and finds that $h_s$ must be highly singlet in the $h_2$ scenario. Dark matter can be Singlino- or Higgsino-dominated in the $h_1$ case and Higgsino-dominated in the $h_2$ case, with distinct annihilation channels and benchmark points illustrating viable DM within current constraints. The results link the extended Higgs sector to DM phenomenology and EWPT dynamics, suggesting potential gravitational-wave signatures and guiding future explorations of their cosmological implications.

Abstract

The search for light scalar and pseudoscalar particles not only provides a promising avenue for probing physics beyond the Standard Model, but also enables a strong first-order electroweak phase transition, thereby offering a viable mechanism to explain the observed baryon asymmetry of the universe. In this study, we investigate exotic decay channels of the 125 GeV SM-like Higgs boson into pairs of light CP-odd or CP-even Higgs bosons within the framework of GNMSSM. A comprehensive parameter space scan is performed using the MultiNest algorithm, incorporating constraints from HiggsSignals-2.6.2, HiggsBounds-5.10.2 and ATLAS experimental searches, under two distinct scenarios(one in which the observed Higgs boson corresponds to the lighter CP-even state, and another where it is identified with the heavier state). Our results demonstrate that HiggsBounds imposes the most stringent exclusion limits due to its sensitivity to direct searches for non-Standard Model Higgs bosons. Furthermore, dark matter phenomenology indicates that Singlino- or Higgsino-dominated DM is viable in the h_1 scenario, whereas the $h_2$ scenario favors Higgsino-dominated DM.

Figures (6)

• Figure 1: Surviving parameter samples after we applied the basic constraints in Sec. 3.1 were projected onto the plane of $\sigma(h)/\sigma_{SM}(h)Br(h \to a_1 a_1\to bb \tau \tau)$ versus $m_{a_1}$. The blue points represent the surviving samples after further constraints by HiggsTools (HT); the black solid line denotes the ATLAS exclusion limit for the $h \to a_1 a_1 \to bb \tau\tau$ channel ATLAS2024. The left and right panels correspond to the $h_1$ and $h_2$ scenarios, respectively.
• Figure 2: Parameter samples excluded by HiggsTools in Figure \ref{['fig1']} are color-coded based on the exclusion source. The red diamond points denote samples that only HiggsSignals (HS) excludes, the orange square points denote samples that only HiggsBounds (HB) excludes, and the magenta pentagon points denote samples that both HB and HS exclude.
• Figure 3: Similar to the right plot in Figure \ref{['fig2']}, the label of the horizontal axis is $\text{Br}(h_2 \to h_1h_1\to \tau\tau bb)$.
• Figure 4: Relationship between parameters $\lambda$ and $\kappa$, similar to Figure \ref{['fig1']}.
• Figure 5: SM-like Higgs boson component in the $h_1$ scenario, similar to Figure \ref{['fig1']}.