Top-squarks (stops) play a crucial role for the naturalness of supersymmetry (SUSY). However, searching for the stops is a tough task at the LHC. To dig the stops out of the huge LHC data, various expert-constructed kinematic variables or cutting-edge analysis techniques have been invented. In this paper, we propose to represent collision events as event graphs and use the message passing neutral network (MPNN) to analyze the events. As a proof-of-concept, we use our method in the search of the stop pair production at the LHC, and find that our MPNN can efficiently discriminate the signal and back-ground events. In comparison with other machine learning methods (e.g. DNN), MPNN can enhance the mass reach of stop mass by several tens of GeV to over a hundred GeV.

Given that the LHC experiment has produced strong constraints on the colored supersymmetric particles (sparticles), testing the electroweak supersymmetry (EWSUSY) will be the next crucial task at the LHC. On the other hand, the light electroweakinos and sleptons in the EWSUSY can also contribute to the dark matter (DM) and low energy lepton observables. The precision measurements of them will provide the indirect evidence of SUSY. In this work, we confront the EWSUSY with the muon g − 2 anomaly, the DM relic density, the direct detection limits and the latest LHC Run-2 data. We find that the sneutrino DM or the neutralino DM with sizable higgsino component has been excluded by the direct detections. Then two viable scenarios are pinned down: one has the light compressed bino and sleptons but heavy higgsinos, and the other has the light compressed bino, winos and sleptons. In the former case, the LSP and slepton masses have to be smaller than about 350 GeV. While in the latter case, the LSP and slepton masses have to be smaller than about 700 GeV and 800 GeV, respectively. From investigating the observability of these sparticles in both scenarios at future colliders, it turns out that the HE-LHC with a luminosity of 15 ab⁻¹ can exclude the whole BHL and most part of BWL scenarios at 2σ level. The precision measurement of the Higgs couplings at the lepton colliders could play a complementary role of probing the BWL scenario.

Measuring the triple Higgs boson coupling is a crucial task in the LHC and future collider experiments. We apply the message passing neural network (MPNN) to the study of nonresonant Higgs pair production process $pp\to hh$ in the final state with $2b+2\ell +E_{\mathrm{T}}^{\mathrm{miss}}$ at the LHC. Although the MPNN can improve the signal significance, it is still challenging to observe such a process at the LHC. We find that a $2\sigma$ upper bound (including a 10% systematic uncertainty) on the production cross section of the Higgs pair is 3.7 times the predicted Standard Model cross section at the LHC with the luminosity of $3000{\mathrm{fb}}^{-1}$, which will limit the triple Higgs boson coupling to the range of $[-3,11.5]$.

We study the decay of $B^{+}$ meson into $K^{+}$ plus a light mediator $\varphi$, which subsequently decays into a dark matter pair, $\overline{\chi }\chi$. Integrating constraints from DM relic density, direct detection, collider data and $B$-physics, alongside the recently reported results form Belle II experiment, we analyze the couplings between the mediator, standard model fermions, and the dark matter particles. Our results indicate that if the decay process $\varphi \to \overline{\chi }\chi$ is kinematically allowed, i.e., $m_{\varphi }>2m_{\chi }$, then the mediator mass must be constrained within $0.35\mathrm{GeV}\lesssim m_{\varphi }\lesssim 3\mathrm{GeV}$. Conversely, if $m_{\varphi }<2m_{\chi }$, the mediator $m_{\varphi }$ is long-lived relative to the detector size, and the only allowed decay channel is $\varphi \to e^{+}{e}^{-}$.

The Galactic center gamma-ray excess (GCE) is a long-standing unsolved problem. One of candidate solutions, the dark matter (DM) annihilation, has been recently tested with other astrophysical observations, such as AMS-02 electron-positron spectra, Fermi Dwarf spheroidal galaxies gamma-ray data, and so on. By assuming that the DM particles annihilate purely into a normal charged fermion pair, Di Mauro and Winkle (2021) claimed that only a muon-pair is compatible with the null detection of all the corresponding astrophysical measurements and can explain GCE simultaneously. On the other hand, a muonphilic DM model may also lead to a signal in the recent Fermilab muon g − 2 measurement or be constrained by the latest PandaX-4T limit. In this work, we comprehensively study interactions between DM and muon, including various combinations of DM and mediator spins. In agreement with GCE (not only 2μ but also 4μ final states), we test these interactions against all the thermal DM constraints. Our results show that only the parameter space near the resonance region of mediator can explain GCE and relic density simultaneously, and larger parameter spaces are still allowed if other poorly-known systematic uncertainties are included. Regardless of the DM spin, only the interactions with the spin-0 mediator can explain the recent muon g − 2 excess on top of GCE, relic density, and other DM and mediator constraints.

In the minimal supersymmetric standard model (MSSM) the lightest superparticle (LSP) can be a TeV neutralino (mainly dominated by higgsino or wino) which serves as a dark matter candidate with...