Discovering Higgs Bosons of the MSSM using Jet Substructure

TL;DR

The paper proposes a novel strategy to discover MSSM Higgs bosons at the LHC by exploiting boosted Higgs decays produced in superpartner cascades. It introduces a dedicated jet-substructure algorithm to identify h→bb within complex SUSY events and demonstrates its effectiveness across multiple Supersymmetric Higgs Study Points, including both high- and low-m_A regimes and a relic-density–motivated point. The results indicate that, with modest luminosity, the lightest MSSM Higgs could be observed via its bb decay mode, potentially outperforming conventional search channels in certain regions of parameter space. The work highlights the strong interplay between Higgs phenomenology, SUSY cascades, and dark matter considerations, and calls for full detector-level studies to realize these prospects.

Abstract

We present a qualitatively new approach to discover Higgs bosons of the MSSM at the LHC using jet substructure techniques applied to boosted Higgs decays. These techniques are ideally suited to the MSSM, since the lightest Higgs boson overwhelmingly decays to $b\bar{b}$ throughout the entire parameter space, while the heavier neutral Higgs bosons, if light enough to be produced in a cascade, also predominantly decay to $b\bar{b}$. The Higgs production we consider arises from superpartner production where superpartners cascade decay into Higgs bosons. We study this mode of Higgs production for several superpartner hierarchies: $m_{\tilde{q}}, m_{\tilde g} > m_{\tilde{W},\tilde{B}} > m_h + μ$; $m_{\tilde{q}}, m_{\tilde g} > m_{\tilde{W},\tilde{B}} > m_{h,H,A} + μ$; and $m_{\tilde{q}}, m_{\tilde g} > m_{\tilde{W}} > m_h + μ$ with $m_{\tilde{B}} \simeq μ$. In these cascades, the Higgs bosons are boosted, with $p_T > 200$ GeV a large fraction of the time. Since Higgs bosons appear in cascades originating from squarks and/or gluinos, the cross section for events with at least one Higgs boson can be the same order as squark/gluino production. Given 10 fb$^{-1}$ of 14 TeV LHC data, with $m_{\tilde{q}} \lsim 1$ TeV, and one of the above superpartner mass hierarchies, our estimate of $S/\sqrt{B}$ of the Higgs signal is sufficiently high that the $b\bar{b}$ mode can become the discovery mode of the lightest Higgs boson of the MSSM.

Figures (11)

• Figure 1: The branching ratios of heavier gaugino-like neutralinos and charginos into lighter Higgsino-like ones plus the lightest Higgs boson is shown for the following parameters: We take $100 \; \mathrm{GeV} \; < M_1 = M_2/2 < 400$ GeV for all Figures, $\left|\mu\right| = 150~\text{GeV}$ in plots I and III and $\left|\mu\right| = 200~\text{GeV}$ in plots II. Plots I and II have heavier sleptons, $m_{\tilde{l}} > 800$ GeV, so that two-body decays are kinematically forbidden. In plot III, we take $m_{\tilde{l}} = 500$ GeV, which allows the wino to decay to left-handed sleptons once $M_2 > 500$ GeV. This is why the branching ratios of $\chi^0_4$, $\chi^\pm_2$ decrease above $M_1/|\mu| > 1.7$.
• Figure 2: The branching ratios for decays to the lightest Higgs boson as a function of $M_1/\mu$. The MSSM parameters for each plot are the same as the three rows in Fig. \ref{['fig:br1a']}. Here $\tilde{q}_L$ refers to the sum of $\tilde{u}_L$ and $\tilde{d}_L$ (both components of the electroweak doublet), while $\tilde{q}_R$ refers to either $\tilde{u}_R$ or $\tilde{d}_R$.
• Figure 3: The fraction (in %) of boosted Higgs bosons as a function of $M_1/\mu$ with $M_2 = 2 M_1$, $\mu = 150~\text{GeV}$ and $\tan\beta = 10$ in samples of events generated by PYTHIA. In the plots the red and dotted lines represent the percentages of Higgs bosons with $p_T > 200~\text{GeV}$ and the green dot-dashed lines represent the fraction of Higgs with $p_T > 300~\text{GeV}$. In the left Figure the squark masses are $1~\text{TeV}$, while in the right Figure the squark masses are $750$ GeV. All other relevant soft supersymmetric breaking masses are kept at or above $1$ TeV.
• Figure 4: The branching ratio for decays to a Higgs boson is shown as a function of $M_1/\mu$ for $m_A = 150~\text{GeV}$, $\left|\mu\right| = 150~\text{GeV}$, and $\tan\beta = 4$. The upper plot shows the decay rates of heavy gauginos into the lightest Higgs boson, while the lower plot shows the summed decay rates to the heavier Higgs bosons $H/A$. The squark and slepton masses are taken to be $1$ TeV.
• Figure 5: The branching ratio for squark decays to a Higgs boson as a function of $M_1/\mu$ for $m_A = 150~\text{GeV}$, $\left|\mu\right| = 150~\text{GeV}$, and $\tan\beta = 4$. The upper plot shows the decay rate to the lightest Higgs boson, while the lower plot shows the summed decay rate to the heavier Higgs bosons $H/A$. As in Figure. \ref{['fig:br1b']}, $\tilde{q}_L$ refers to the sum of $\tilde{u}_L$ and $\tilde{d}_L$, while $\tilde{q}_R$ refers to either $\tilde{u}_R$ or $\tilde{d}_R$.The squark and slepton masses are taken to be $1$ TeV.