|
ATLAS Collaboration(Aad, G. et al), Aikot, A., Amos, K. R., Aparisi Pozo, J. A., Bailey, A. J., Bouchhar, N., et al. (2024). Studies of new Higgs boson interactions through nonresonant HH production in the b(b)over-barγγ final state in pp collisions at √s=13 TeV with the ATLAS detector. J. High Energy Phys., 01(1), 066–48pp.
Abstract: A search for nonresonant Higgs boson pair production in the b (b) over bar gamma gamma final state is performed using 140 fb(-1) of proton-proton collisions at a centre-of-mass energy of 13 TeV recorded by the ATLAS detector at the CERN Large Hadron Collider. This analysis supersedes and expands upon the previous nonresonant ATLAS results in this final state based on the same data sample. The analysis strategy is optimised to probe anomalous values not only of the Higgs (H) boson self-coupling modifier kappa(lambda) but also of the quartic HHVV (V = W, Z) coupling modifier kappa(2V). No significant excess above the expected background from Standard Model processes is observed. An observed upper limit mu(HH) < 4.0 is set at 95% confidence level on the Higgs boson pair production cross-section normalised to its Standard Model prediction. The 95% confidence intervals for the coupling modifiers are -1.4 < kappa(lambda) < 6.9 and -0.5 < kappa(2V) < 2.7, assuming all other Higgs boson couplings except the one under study are fixed to the Standard Model predictions. The results are interpreted in the Standard Model effective field theory and Higgs effective field theory frameworks in terms of constraints on the couplings of anomalous Higgs boson (self-)interactions.
|
|
|
Botella, F. J., Branco, G. C., Nebot, M., & Rebelo, M. N. (2011). Two-Higgs leptonic minimal flavour violation. J. High Energy Phys., 10(10), 037–21pp.
Abstract: We construct extensions of the Standard Model with two Higgs doublets, where there are flavour changing neutral currents both in the quark and leptonic sectors, with their strength fixed by the fermion mixing matrices V(CKM) and V(PMNS). These models are an extension to the leptonic sector of the class of models previously considered by Branco, Grimus and Lavoura, for the quark sector. We consider both the cases of Dirac and Majorana neutrinos and identify the minimal discrete symmetry required in order to implement the models in a natural way.
|
|
|
Fidalgo, J., Lopez-Fogliani, D. E., Muñoz, C., & Ruiz de Austri, R. (2011). The Higgs sector of the μnu SSM and collider physics. J. High Energy Phys., 10(10), 020–33pp.
Abstract: The μnu SSM is a supersymmetric standard model that accounts for light neutrino masses and solves the μproblem of the MSSM by simply using right-handed neutrino superfields. Since this mechanism breaks R-parity, a peculiar structure for the mass matrices is generated. The neutral Higgses are mixed with the right- and left-handed sneutrinos producing 8x8 neutral scalar mass matrices. We analyse the Higgs sector of the μnu SSM in detail, with special emphasis in possible signals at colliders. After studying in general the decays of the Higges, we focus on those processes that are genuine of the μnu SSM, and could serve to distinguish it form other supersymmetric models. In particular, we present viable benchmark points for LHC searches. For example, we find decays of a MSSM-like Higgs into two lightest neutralinos, with the latter decaying inside the detector leading to displaced vertices, and producing final states with 4 and 8 b-jets plus missing energy. Final states with leptons and missing energy are also found.
|
|
|
Jung, M., Li, X. Q., & Pich, A. (2012). Exclusive radiative B-meson decays within the aligned two-Higgs-doublet model. J. High Energy Phys., 10(10), 063–33pp.
Abstract: In the aligned two-Higgs-doublet model, the alignment of Yukawa matrices in flavour space guarantees the absence of tree-level flavour-changing neutral currents, while allowing at the same time for new sources of CP violation, implying potentially large effects in many low-energy processes. In this work we study the constraints from exclusive radiative B -> V gamma decays, where V denotes a light vector meson. The current experimental data on the CP-averaged branching ratios and the direct CP and isospin asymmetries are analyzed. It is found that, while the branching ratios and direct CP asymmetries do not constrain the parameter space much further compared to the inclusive B -> X-s,X-d gamma decays, complementary constraints can be obtained from the isospin asymmetries Delta(K*gamma) and Delta(rho gamma). In addition, correlations between the various observables in exclusive B -> V gamma and inclusive B -> X-s,X-d gamma decays are investigated in detail, and predictions are made for several so far unmeasured observables.
|
|
|
ATLAS Collaboration(Aaboud, M. et al), Alvarez Piqueras, D., Barranco Navarro, L., Cabrera Urban, S., Castillo Gimenez, V., Cerda Alberich, L., et al. (2017). Searches for the Z gamma decay mode of the Higgs boson and for new high-mass resonances in pp collisions at root s=13 TeV with the ATLAS detector. J. High Energy Phys., 10(10), 112–51pp.
Abstract: This article presents searches for the Z gamma decay of the Higgs boson and for narrow high-mass resonances decaying to Z gamma, exploiting Z boson decays to pairs of electrons or muons. The data analysis uses 36.1 fb(-1) of pp collisions at root s = 13 recorded by the ATLAS detector at the CERN Large Hadron Collider. The data are found to be consistent with the expected Standard Model background. The observed (expected – assuming Standard Model pp -> H -> Z gamma production and decay) upper limit on the production cross section times the branching ratio for pp -> H -> Z gamma is 6.6. (5.2) times the Standard Model prediction at the 95% confidence level for a Higgs boson mass of 125.09 GeV. In addition, upper limits are set on the production cross section times the branching ratio as a function of the mass of a narrow resonance between 250 GeV and 2.4 TeV, assuming spin-0 resonances produced via gluon-gluon fusion, and spin-2 resonances produced via gluon-gluon or quark-antiquark initial states. For high-mass spin-0 resonances, the observed (expected) limits vary between 88 fb (61 fb) and 2.8 fb (2.7 fb) for the mass range from 250 GeV to 2.4 TeV at the 95% confidence level.
|
|