Shedding Light on Dark Matter via the Higgs Portal

TL;DR

This work reports CMS Run-2 results testing Higgs-portal dark matter scenarios at $\sqrt{s}=13$ TeV by searching for DM produced in association with the SM Higgs and a dark Higgs. It combines three analyses—mono-Higgs with $h\to b\bar{b}$ and $h\to \tau\tau$, plus a mono dark Higgs search with $H_D\to b\bar{b}$—employing both resolved and boosted jet strategies and state-of-the-art tagging (DeepJet, ParticleNet, DeepTau, DeepAK15) along with data-driven background estimation. No significant deviations from SM expectations are observed, leading to 95% CL limits on mediator and dark-sector parameters across the explored spaces: $(m_{Z'}, m_\chi)$ and $(m_a, m_A, \sin\theta, \tan\beta)$, with some interpretations fixing $m_\chi=10$ GeV. These results tighten Higgs-portal dark matter constraints and illustrate the ongoing potential for Run-3 and HL-LHC to further probe Higgs-mediated couplings to dark matter.

Abstract

A selection of new results from the CMS experiment that probe Higgs-portal frameworks are presented. These searches target scenarios in which dark matter particles are produced in association with the Standard Model Higgs boson. No significant deviations from the Standard Model predictions are observed, and new limits are set using the Run-2 proton-proton collision dataset at $\sqrt{s} = 13$ TeV.

Figures (3)

• Figure 1: The 95% CL upper limit on signal strength $\mu$ for baryonic-$\textrm{Z}^{\prime}$ (left) in the ($m_{\textrm{Z}^{\prime}}$, $m_{\chi}$) plane and for 2HDM+a (right) as a function of model parameters: $m_{\textrm{a}}\xspace$, $m_{\textrm{A}}\xspace$, $\sin\theta\xspace$, and $\tan\beta\xspace$ while fixing the values of other parameters, as indicated in the figures pas-sus-24-007.
• Figure 2: The 95% CL upper limit on signal strength $\mu$ for baryonic-$\textrm{Z}^{\prime}$ (left) in the ($m_{\textrm{Z}^{\prime}}$, $m_{\chi}$) plane and for 2HDM+a (right) as a function of model parameters: $m_{\textrm{a}}\xspace$, $m_{\textrm{A}}\xspace$, $\sin\theta\xspace$, and $\tan\beta\xspace$ while fixing the values of other parameters, as indicated in the figures pas-sus-23-012.
• Figure 3: The expected and observed exclusion limits at the 95% CL on the signal strength $\mu=\sigma/\sigma_{theory}$ as a function of $m_{\textrm{Z}^{\prime}}$ and $m_{\chi}$ for $m_{\textrm{H}_{\textrm{D}}}$ hypotheses of 50, 70, 90, 110, 130, and 150 GeV. Only scenarios with $m_{\chi} > m_{\textrm{H}_{\textrm{D}}}$ are considered. The black solid line indicates the observed exclusion boundary corresponding to $\mu=1$. The black dashed and dotted lines represent the expected exclusion and the 68 and 95% CL intervals around the expected boundary, respectively. Parameter combinations corresponding to larger values of $\mu$ are excluded pas-sus-23-013.