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ATLAS Collaboration(Aad, G. et al), Aikot, A., Amos, K. R., Bouchhar, N., Cabrera Urban, S., Cantero, J., et al. (2025). Combination of searches for singly and doubly charged Higgs bosons pvroduced via vector-boson fusion in proton-proton collisions at √s=13 TeV with the ATLAS detector. Phys. Lett. B, 860, 139137–21pp.
Abstract: A combination of searches for singly and doubly charged Higgs bosons, H-+/- and H-+/-+/-, produced via vector-boson fusion is performed using 140 fb(-1) of proton-proton collisions at a centre-of-mass energy of 13 TeV, collected with the ATLAS detector during Run 2 of the Large Hadron Collider. Searches targeting decays to massive vector bosons in leptonic final states (electrons or muons) are considered. New constraints are reported on the production cross section times branching fraction for charged Higgs boson masses between 200 GeV and 3000 GeV. The results are interpreted in the context of the Georgi-Machacek model for which the most stringent constraints to date are set for the masses considered in the combination.
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IceCube Collaboration(Abbasi, R. et al), & Garcia, A. (2024). Search for an eV-Scale Sterile Neutrino Using Improved High-Energy νμ Event Reconstruction in IceCube. Phys. Rev. Lett., 133(20), 201804–10pp.
Abstract: This Letter presents the result of a 3 + 1 sterile neutrino search using 10.7 yr of IceCube data. We analyze atmospheric muon neutrinos that traverse the Earth with energies ranging from 0.5 to 100 TeV, incorporating significant improvements in modeling neutrino flux and detector response compared to earlier studies. Notably, for the first time, we categorize data into starting and throughgoing events, distinguishing neutrino interactions with vertices inside or outside the instrumented volume, to improve energy resolution. The best-fit point for a 3 + 1 model is found to be at sin(2)(2 theta(24)) = 0.16 and Delta m(41)(2) = 3.5 eV(2), which agrees with previous iterations of this Letter. The result is consistent with the null hypothesis of no sterile neutrinos with a p value of 3.1%.
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ATLAS Collaboration(Aad, G. et al), Aikot, A., Amos, K. R., Bouchhar, N., Cabrera Urban, S., Cantero, J., et al. (2024). Calibration of a soft secondary vertex tagger using proton-proton collisions at √s=13 TeV with the ATLAS detector. Phys. Rev. D, 110(3), 032015–30pp.
Abstract: Several processes studied by the ATLAS experiment at the Large Hadron Collider produce low-momentum b-flavored hadrons in the final state. This paper describes the calibration of a dedicated tagging algorithm that identifies b-flavored hadrons outside of hadronic jets by reconstructing the soft secondary vertices originating from their decays. The calibration is based on a proton-proton collision dataset at a center-of-mass energy of 13 TeV corresponding to an integrated luminosity of 140 fb(-1). Scale factors used to correct the algorithm's performance in simulated events are extracted for the b-tagging efficiency and the mistag rate of the algorithm using a data sample enriched in t (t) over bar events. Several orthogonal measurement regions are defined, binned as a function of the multiplicities of soft secondary vertices and jets containing a b-flavored hadron in the event. The mistag rate scale factors are estimated separately for events with low and high average numbers of interactions per bunch crossing. The results, which are derived from events with low missing transverse momentum, are successfully validated in a phase space characterized by high missing transverse momentum and therefore are applicable to new physics searches carried out in either phase space regime.
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LHCb Collaboration(Aaij, R. et al), Fernandez Casani, A., Jaimes Elles, S. J., Jashal, B. K., Libralon, S., Martinez-Vidal, F., et al. (2024). Observation of muonic Dalitz decays of chib mesons and precise spectroscopy of hidden-beauty states. J. High Energy Phys., 10(10), 122–28pp.
Abstract: The decays of the chi(b1)(1P), chi(b2)(1P), chi(b1)(2P) and chi(b2)(2P) mesons into the Upsilon(1S)mu(+)mu(-) final state are observed with a high significance using proton-proton collision data collected with the LHCb detector and corresponding to an integrated luminosity of 9 fb(-1). The newly observed decays together with the Upsilon(2S) -> Upsilon(1S)pi(+)pi(-) and Upsilon(3S) -> Upsilon(2S)pi(+)pi(-) decay modes are used for precision measurements of the mass and mass splittings for the hidden-beauty states.
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ATLAS Collaboration(Aad, G. et al), Aikot, A., Amos, K. R., Bouchhar, N., Cabrera Urban, S., Cantero, J., et al. (2024). Combination of Searches for Higgs Boson Pair Production in pp Collisions at √s=13 TeV with the ATLAS Detector. Phys. Rev. Lett., 133(10), 101801–22pp.
Abstract: This Letter presents results from a combination of searches for Higgs boson pair production using 126-140 fb(-1) of proton-proton collision data at root s = 13 TeV recorded with the ATLAS detector. At 95% confidence level (CL), the upper limit on the production rate is 2.9 times the standard model (SM) prediction, with an expected limit of 2.4 assuming no Higgs boson pair production. Constraints on the Higgs boson self-coupling modifier kappa(lambda) =lambda(HHH) /lambda(SM)(HHH), and the quartic HHVV coupling modifier kappa(2V) = g(HHVV)/g(HHVV)(SM), are derived individually, fixing the other parameter to its SM value. The observed 95% CL intervals are -1.2 <kappa(lambda)< 7.2 and 0.6 <kappa(2V) < 1.5, respectively, while the expected intervals are -1.6 <kappa(lambda)< 7.2 and 0.4 <kappa(2V) < 1.6 in the SM case. Constraints obtained for several interaction parameters within Higgs effective field theory are the strongest to date, offering insights into potential deviations from SM predictions.
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