Probing the Higgs Portal at the LHC Through Resonant di-Higgs Production

TL;DR

This work studies resonant di-Higgs production in Higgs portal scenarios featuring a real singlet, yielding two mixed scalars h1 and h2 with m1=125 GeV and m2>2m1. Using the xSM as a minimal portal model and gluon-fusion production, the authors quantify the LHC discovery potential in the bbττ final state, mapping the results onto the NMSSM decoupling limit and cosmological motivations such as a strong first order EWPT. They perform detailed collider analyses across four tau/jet final states, showing that a 5-sigma discovery could be achieved with O(100) fb^-1 in several channels, particularly the bbττ leptonic/hadronic combinations, while noting systematic uncertainties in purely hadronic backgrounds. Overall, the study highlights resonant h2 decays as a viable probe of extended scalar sectors with significant implications for electroweak symmetry breaking, baryogenesis, and dark matter phenomenology, and it outlines directions for exploring additional final states and improved background treatment.

Abstract

We investigate resonant di-Higgs production as a means of probing extended scalar sectors that include a 125 GeV Standard Model-like Higgs boson. For concreteness, we consider a gauge singlet Higgs portal scenario leading to two mixed doublet-singlet states, h_1,2. For m_h_2 > 2 m_h_1, the resonant di-Higgs production process p p -> h_2 -> h_1 h_1 will lead to final states associated with the decaying pair of Standard Model-like Higgs scalars. We focus on h_2 production via gluon fusion and on the b b tau^+ tau^- final state. We find that discovery of the h_2 at the LHC may be achieved with ~ 100 fb^-1 of integrated luminosity for benchmark parameter choices relevant to cosmology. Our analysis directly maps onto the decoupling limits of the Next-to-Minimal Supersymmetric Standard Model (NMSSM) and more generically onto extensions of the Standard Model Higgs sector in which a heavy scalar produced through gluon fusion decays to a pair of Standard Model-like Higgs bosons.

Figures (10)

• Figure 1: Absolute stability region for the EW vacuum in the $(a_2, b_3)$ plane for $b_4 = 1$, $c_\theta = 0.812404$ and $m_2 = 270$ GeV (solid-black), $m_2 = 370$ GeV (dashed-red). The black dots correspond to the benchmark scenarios used in the analysis (see section IV).
• Figure 2: Normalized $|{\vec{P}}_T|$ distribution for the $b \bar{b}$ system, for both signal and the dominant backgrounds.
• Figure 3: Normalized $\Delta R_{bb}$ distribution after event selection (before cuts) for signal and background ('' $\tau_\mathrm{lep}\tau_\mathrm{lep}$").
• Figure 4: Normalized $m_{bb}$ distribution after event selection (before cuts) for signal and background ('' $\tau_\mathrm{lep}\tau_\mathrm{lep}$").
• Figure 5: Normalized $P_{T,b_1}$ distribution after event selection (before cuts) for signal and background ('' $\tau_\mathrm{lep}\tau_\mathrm{lep}$").