A search for charginos and neutralinos at the Large Hadron Collider using fully hadronic final states and missing transverse momentum is reported. Pair-produced charginos or neutralinos are explored, each decaying into a high-p T Standard Model weak boson. Fully hadronic final states are studied to exploit the advantage of the large branching ratio, and the efficient rejection of backgrounds by identifying the high-p T bosons using large-radius jets and jet substructure information. An integrated luminosity of 139 fb −1 of proton-proton collision data collected by the ATLAS detector at a center-of-mass energy of 13 TeV is used. No significant excess is found beyond the Standard Model expectation. Exclusion limits at the 95% confidence level are set on wino or higgsino production with various assumptions about the decay branching ratios and the type of lightest supersymmetric particle. A wino (higgsino) mass up to 1060 (900) GeV is excluded when the lightest supersymmetry particle mass is below 400 (240) GeV and the mass splitting is larger than 400 (450) GeV. The sensitivity to high-mass winos and higgsinos is significantly extended relative to previous LHC searches using other final states.

The ATLAS Collaboration A search is made for a vector-like 𝑇 quark decaying into a Higgs boson and a top quark in 13 TeV proton-proton collisions using the ATLAS detector at the Large Hadron Collider with a data sample corresponding to an integrated luminosity of 139 fb −1. The Higgs-boson and top-quark candidates are identified in the all-hadronic decay mode, where 𝐻 → 𝑏 b and 𝑡 → 𝑏𝑊 → 𝑏𝑞 q are reconstructed as large-radius jets. The candidate Higgs boson, top quark, and associated B-hadrons are identified using tagging algorithms. No significant excess is observed above the background, so limits are set on the production cross-section of a singlet 𝑇 quark at 95% confidence level, depending on the mass, 𝑚 𝑇 , and coupling, 𝜅 𝑇 , of the vector-like 𝑇 quark to Standard Model particles. In the considered mass range between 1.0 and 2.3 TeV, the upper limit on the allowed coupling values increases with 𝑚 𝑇 from a minimum value of 0.35 for 1.07 < 𝑚 𝑇 < 1.4 TeV to 1.6 for 𝑚 𝑇 = 2.3 TeV.

Charged Higgs boson is a crucial prediction of new physics beyond the SM. In this work, we perform a comprehensive scan over the parameter space of NMSSM considering various experimental constraints including the direct search limits from the 13 TeV LHC, and consider the scenario that the next-to-lightest CP-even Higgs boson is SM-like. We find that the masses of charged Higgs bosons can be as light as 350 GeV, the lightest CP-even Higgs boson h 1 is predominantly singlet and can be as light as 48 GeV, and the lightest CP-odd Higgs boson a 1 is also singlet-dominated and can be as light as 82 GeV. The charged Higgs bosons mainly decay to tb ortb, but the branching ratio of the exotic decays H ± → W ± h 1 and H ± → W ± a 1 can maximally reach to 20% and 11%, respectively, which can be used to distinguish the NMSSM from MSSM. Such a heavy charged Higgs boson is unaccessible at the 13 TeV LHC with a luminosity of 36.1 fb −1 and its detection needs higher energy and/or higher luminosity. Both the ATLAS [1] and CMS [2] collaborations at the large Hadron Collider (LHC)announced the discovery of a Higgs boson with mass about 125 GeV in 2012, which implies that the standard model (SM) of elementary particles is fully established. However, many new physics models beyond the SM with extended Higgs sectors, such as the Minimal Supersymmetric Standard Model (MSSM) [3], can also accommodate a 125 GeV Higgs boson.The MSSM consists of two Higgs doublet fields, which generate the masses of up-and downtype fermions. To realize a 125 GeV Higgs, the MSSM needs large radiative corrections from the third generation squark loops [4][5][6][7], which makes the MSSM unnatural. And the MSSM also suffers from the µ-problem. However, these problems can be remedied in the Next-to-MSSM (NMSSM) [8], which extends the Higgs sector with an additional Higgs singlet field S. The effective µ-term can be generated whenŜ acquires vacuum expectation value (vev).The coupling between the singlet and doublet Higgs fields can easily enhance the mass of the Higgs boson to be 125 GeV without large radiative corrections [9][10][11][12][13][14][15][16][17][18][19][20]. In contrast to the MSSM, the NMSSM has richer Higgs spectrum, which contains three CP-even Higgs bosons, two CP-odd Higgs bosons and a pair of charged Higgs bosons H ± . Needless to say, the discovery of extra Higgs bosons along with the SM-like Higgs boson will clearly confirm the existence of new physics beyond the SM.Because of the different interactions and decay modes from neutral Higgs bosons, the studies of charged Higgs bosons have been received more and more attentions [21][22][23][24][25]. For charged Higgs bosons lighter than top-quark, they are mainly produced through top quark decay t → bH + , and primarily decay to τ ν and sc. For charged Higgs bosons heavier than top-quark, they are produced at the LHC directly through the processes pp → tbH ± , the pair production process pp → H + H − and also the associated production with a neutral Higgs boson, then they may be searched via th...

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