Search for a heavy charged Higgs boson decaying into a $W$ boson and a Higgs boson in final states with leptons and $b$-jets in $\sqrt{s} = 13$ TeV $pp$ collisions with the ATLAS detector
ArXiv 2411.03969 (2024)
Search for neutral long-lived particles that decay into displaced jets in the ATLAS calorimeter in association with leptons or jets using pp collisions at s = 13 TeV
Journal of High Energy Physics Springer 2024:11 (2024) 36
Abstract:
A search for neutral long-lived particles (LLPs) decaying in the ATLAS hadronic calorimeter using 140 fb−1 of proton-proton collisions at s = 13 TeV delivered by the LHC is presented. The analysis is composed of three channels. The first targets pair-produced LLPs, where at least one LLP is produced with sufficiently low boost that its decay products can be resolved as separate jets. The second and third channels target LLPs respectively produced in association with a W or Z boson that decays leptonically. In each channel, different search regions target different kinematic regimes, to cover a broad range of LLP mass hypotheses and models. No excesses of events relative to the background predictions are observed. Higgs boson branching fractions to pairs of hadronically decaying neutral LLPs larger than 1% are excluded at 95% confidence level for proper decay lengths in the range of 30 cm to 4.5 m depending on the LLP mass, a factor of three improvement on previous searches in the hadronic calorimeter. The production of long-lived dark photons in association with a Z boson with cross-sections above 0.1 pb is excluded for dark photon mean proper decay lengths in the range of 20 cm to 50 m, improving previous ATLAS results by an order of magnitude. Finally, long-lived photo-phobic axion-like particle models are probed for the first time by ATLAS, with production cross-sections above 0.1 pb excluded in the 0.1 mm to 10 m range.
A search for triple Higgs boson production in the 6b final state using pp collisions at s√=13 TeV with the ATLAS detector
Phys. Rev. D 111, 032006 – Published 13 February, 2025 - arXiv:2411.02040
Abstract:
A search for the production of three Higgs bosons (HHH) in the bb¯bb¯bb¯ final state is presented. The search uses 126 fb−1 of proton-proton collision data at s√=13 TeV collected with the ATLAS detector at the Large Hadron Collider. The analysis targets both non-resonant and resonant production of HHH. The resonant interpretations primarily consider a cascade decay topology of X→SH→HHH with masses of the new scalars X and S up to 1.5 TeV and 1 TeV, respectively. In addition to scenarios where S is off-shell, the non-resonant interpretation includes a search for standard model (SM) HHH production, with limits on the tri-linear and quartic Higgs self-coupling set. No evidence for HHH production is observed. An upper limit of 59 fb is set, at 95% confidence level, on the cross-section for Standard-Model HHH production.
A search for triple Higgs boson production in the $6b$ final state using $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
(2024)
Characterisation of the Effects of Radiation Damage on Low Gain Avalanche Diodes for Low-LET Microdosimetry
Institute of Electrical and Electronics Engineers (IEEE) 00 (2024) 1-1