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ATLAS Collaboration(Aad, G. et al), Amos, K. R., Aparisi Pozo, J. A., Bailey, A. J., Bouchhar, N., Cabrera Urban, S., et al. (2023). Search for heavy long-lived multi-charged particles in the full LHC Run 2 pp collision data at √s=13 TeV using the ATLAS detector. Phys. Lett. B, 847, 138316–25pp.
Abstract: A search for heavy long-lived multi-charged particles is performed using the ATLAS detector at the LHC. Data collected in 2015-2018 at root s = 13 TeV from pp collisions corresponding to an integrated luminosity of 139 fb(-1) are examined. Particles producing anomalously high ionization, consistent with long-lived spin-1/2 massive particles with electric charges from |q| = 2e to |q| = 7e are searched for. No statistically significant evidence of such particles is observed, and 95% confidence level cross-section upper limits are calculated and interpreted as the lower mass limits for a Drell-Yan plus photon-fusion production mode. The least stringent limit, 1060 GeV, is obtained for |q| = 2e particles, and the most stringent one, 1600 GeV, is for |q| = 6e particles.
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ATLAS Collaboration(Aad, G. et al), Aparisi Pozo, J. A., Bailey, A. J., Cabrera Urban, S., Castillo, F. L., Castillo Gimenez, V., et al. (2020). Search for Heavy Higgs Bosons Decaying into Two Tau Leptons with the ATLAS Detector Using pp Collisions at root s=13 TeV. Phys. Rev. Lett., 125(5), 051801–22pp.
Abstract: A search for heavy neutral Higgs bosons is performed using the LHC Run 2 data, corresponding to an integrated luminosity of 139 fb(-1) of proton-proton collisions at root s = 13 TeV recorded with the ATLAS detector. The search for heavy resonances is performed over the mass range 0.2-2.5 TeV for the tau(+)tau(-) decay with at least one tau-lepton decaying into final states with hadrons. The data are in good agreement with the background prediction of the standard model. In the M-h(125) scenario of the minimal supersymmetric standard model, values of tan beta > 8 and tan beta > 21 are excluded at the 95% confidence level for neutral Higgs boson masses of 1.0 and 1.5 TeV, respectively, where tan beta is the ratio of the vacuum expectation values of the two Higgs doublets.
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ATLAS Collaboration(Aad, G. et al), Alvarez Piqueras, D., Aparisi Pozo, J. A., Bailey, A. J., Cabrera Urban, S., Castillo, F. L., et al. (2020). Search for heavy neutral Higgs bosons produced in association with b-quarks and decaying into b-quarks at root s=13 TeV with the ATLAS detector. Phys. Rev. D, 102(3), 032004–31pp.
Abstract: A search for heavy neutral Higgs bosons produced in association with one or two b-quarks and decaying to b-quark pairs is presented using 27.8 fb(-1) of root s=13 TeV proton-proton collision data recorded by the ATLAS detector at the Large Hadron Collider during 2015 and 2016. No evidence of a signal is found. Upper limits on the heavy neutral Higgs boson production cross section times its branching ratio to b (b) over bar are set, ranging from 4.0 to 0.6 pb at 95% confidence level over a Higgs boson mass range of 450 to 1400 GeV. Results are interpreted within the two-Higgs-doublet model and the minimal supersymmetric Standard Model.
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ATLAS Collaboration(Aad, G. et al), Aparisi Pozo, J. A., Bailey, A. J., Cabrera Urban, S., Cardillo, F., Castillo, F. L., et al. (2021). Search for heavy resonances decaying into a pair of Z bosons in the l+ l- l '+ l '- and l+ l-nu barnu final states using 139 fb-1 of proton-proton collisions at root s = 13 TeV with the ATLAS detector. Eur. Phys. J. C, 81(4), 332–39pp.
Abstract: A search for heavy resonances decaying into a pair of Z bosons leading to l+l-l ' +l '- and l+l-nu nu <overbar></mml:mover> final states, where l stands for either an electron or a muon, is presented. The search uses proton-proton collision data at a centre-of-mass energy of 13 TeV collected from 2015 to 2018 that corresponds to the integrated luminosity of 139 fb<mml:mo>-1 recorded by the ATLAS detector during Run 2 of the Large Hadron Collider. Different mass ranges spanning 200 GeV to 2000 GeV for the hypothetical resonances are considered, depending on the final state and model. In the absence of a significant observed excess, the results are interpreted as upper limits on the production cross section of a spin-0 or spin-2 resonance. The upper limits for the spin-0 resonance are translated to exclusion contours in the context of Type-I and Type-II two-Higgs-doublet models, and the limits for the spin-2 resonance are used to constrain the Randall-Sundrum model with an extra dimension giving rise to spin-2 graviton excitations.
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ATLAS Collaboration(Aad, G. et al), Aparisi Pozo, J. A., Bailey, A. J., Cabrera Urban, S., Castillo, F. L., Castillo Gimenez, V., et al. (2020). Search for resonances decaying into a weak vector boson and a Higgs boson in the fully hadronic final state produced in proton – proton collisions at root s=13 TeV with the ATLAS detector. Phys. Rev. D, 102(11), 112008–27pp.
Abstract: A search for heavy resonances decaying into a W or Z boson and a Higgs boson produced in proton – proton collisions at the Large Hadron Collider at root s = 13 TeV is presented. The analysis utilizes the dominant W -> q (q) over bar' or Z -> q (q) over bar and H -> b (b) over bar decays with substructure techniques applied to large-radius jets. A sample corresponding to an integrated luminosity of 139 fb(-1) collected with the ATLAS detector is analyzed and no significant excess of data is observed over the background prediction. The results are interpreted in the context of the heavy vector triplet model with spin-1 W' and Z' bosons. Upper limits on the cross section are set for resonances with mass between 1.5 and 5.0 TeV, ranging from 6.8 to 0.53 fb for W' -> WH and from 8.7 to 0.53 fb for Z' -> ZH at the 95% confidence level.
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