Evidence for Higgs boson decays to a low-mass dilepton system and a photon in pp collisions at √s = 13 TeV with the ATLAS detector
Aad, Georges; Abbott, Brad; Abbott, Dale C.; Abed Abud, Adam; Abeling, Kira; Abhayasinghe, Deshan Kavishka; Abidi, Syed Haider; AbouZeid, Ossama Sherif Alexander; Abraham, Nadine L.; Abramowicz, Halina; Bjørke, Kristian; Bugge, Magnar Kopangen; Cameron, David Gordon; Catmore, James Richard; Garonne, Vincent; Gramstad, Eirik; Heggelund, Andreas; Hellesund, Simen; Håland, Even Simonsen; Morisbak, Vanja; Oppen, Henrik; Ould-Saada, Farid; Pedersen, Maiken; Read, Alexander Lincoln; Rye, Eli Bæverfjord; Røhne, Ole Myren; Sandaker, Heidi; Vadla, Knut Oddvar Høie; Buanes, Trygve; Djuvsland, Julia Isabell; Eigen, Gerald; Fomin, Nikolai; Latour, Bertrand Pascal Christian; Lee, Graham Richard; Lipniacka, Anna; Stugu, Bjarne Sandvik; Træet, Are Sivertsen; Abreu, Henso; Abulaiti, Yiming; Abusleme Hoffman, Angel C.; Acharya, Bobby S.; Achkar, Baida; Adam, Lennart; Adam-Bourdarios, Claire; Adamczyk, Leszek; Adamek, Lukas; Adelman, Jareed; Adigüzel, Aytül; Adorni, Sofia; Adye, Tim; ATLAS, Collaboration
Journal article, Peer reviewed
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Original versionPhysics Letters B. 2021, 819, 136412. 10.1016/j.physletb.2021.136412
A search for the Higgs boson decaying into a photon and a pair of electrons or muons with an invariant mass mℓℓ<30 GeV is presented. The analysis is performed using 139 fb−1 of proton–proton collision data, produced by the LHC at a centre-of-mass energy of 13 TeV and collected by the ATLAS experiment. Evidence for the H→ℓℓγ process is found with a significance of 3.2 over the background-only hypothesis, compared to an expected significance of 2.1 for the Standard Model prediction. The best-fit value of the signal-strength parameter, defined as the ratio of the observed signal yield to the one expected in the Standard Model, is μ=1.5±0.5. The Higgs boson production cross-section times the H→ℓℓγ branching ratio for mℓℓ<30 GeV is determined to be 8.7−2.7+2.8 fb.