2,361 research outputs found
Search for Majorana neutrinos in same-sign WW scattering events from pp collisions at √s=13 TeV
A search for Majorana neutrinos in same-sign WW scattering events is presented. The analysis uses √s=13 TeV proton–proton collision data with an integrated luminosity of 140 fb⁻¹ recorded during 2015–2018 by the ATLAS detector at the Large Hadron Collider. The analysis targets final states including exactly two same-sign muons and at least two hadronic jets well separated in rapidity. The modelling of the main backgrounds, from Standard Model same-sign WW scattering and WZ production, is constrained with data in dedicated signal-depleted control regions. The distribution of the transverse momentum of the second-hardest muon is used to search for signals originating from a heavy Majorana neutrino with a mass between 50 GeV and 20 TeV. No significant excess is observed over the background expectation. The results are interpreted in a benchmark scenario of the Phenomenological Type-I Seesaw model. In addition, the sensitivity to the Weinberg operator is investigated. Upper limits at the 95% confidence level are placed on the squared muon-neutrino–heavy-neutrino mass-mixing matrix element |Vμₙ|² as a function of the heavy Majorana neutrino’s mass mN, and on the effective μμ Majorana neutrino mass |mμμ|
Process evaluation of TeamUp: a movement-based psychosocial intervention for refugee children in the Netherlands
Fast b-tagging at the high-level trigger of the ATLAS experiment in LHC Run 3
The ATLAS experiment relies on real-time hadronic jet reconstruction and b-tagging to record fully hadronic events containing b-jets. These algorithms require track reconstruction, which is computationally expensive and could overwhelm the high-level-trigger farm, even at the reduced event rate that passes the ATLAS first stage hardware-based trigger. In LHC Run 3, ATLAS has mitigated these computational demands by introducing a fast neural-network-based b-tagger, which acts as a low-precision filter using input from hadronic jets and tracks. It runs after a hardware trigger and before the remaining high-level-trigger reconstruction. This design relies on the negligible cost of neural-network inference as compared to track reconstruction, and the cost reduction from limiting tracking to specific regions of the detector. In the case of Standard Model HH → bb̅bb̅, a key signature relying on b-jet triggers, the filter lowers the input rate to the remaining high-level trigger by a factor of five at the small cost of reducing the overall signal efficiency by roughly 2%
Search for type-III seesaw heavy leptons in leptonic final states in pp collisions at √s=13TeV with the ATLAS detector
Search for dark matter produced in association with a single top quark in vs=13 TeV pp collisions with the ATLAS detector
Search for Heavy Higgs Bosons Decaying into Two Tau Leptons with the ATLAS Detector Using pp Collisions at root s=13 TeV
Measurements of the Higgs boson inclusive and differential fiducial cross sections in the 4 ℓ decay channel at √s = 13 TeV
Higgs boson production cross-section measurements and their EFT interpretation in the 4 ℓ decay channel at √s= 13 TeV with the ATLAS detector
Search for a heavy Higgs boson decaying into a Z boson and another heavy Higgs boson in the llbb and llWW final states in pp collisions at vs=13 TeV with the ATLAS detector
Observation of the associated production of a top quark and a Z boson in pp collisions at √s = 13 TeV with the ATLAS detector
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