Evidence for Higgs boson decays to a low-mass dilepton system and a photon in pp collisions at √<i>s</i>=13 TeV with the ATLAS detector



Aad, G, Abbott, B, Abbott, DC, Abud, A Abed, Abeling, K, Abhayasinghe, DK, Abidi, SH, AbouZeid, OS, Abraham, NL, Abramowicz, H
et al (show 2869 more authors) (2021) Evidence for Higgs boson decays to a low-mass dilepton system and a photon in pp collisions at √<i>s</i>=13 TeV with the ATLAS detector. PHYSICS LETTERS B, 819. 136412-.

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Abstract

A search for the Higgs boson decaying into a photon and a pair of electrons or muons with an invariant mass $m_{\ell\ell} < 30$ 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 $H \rightarrow \ell \ell \gamma$ process is found with a significance of 3.2$\sigma$ over the background-only hypothesis, compared to an expected significance of 2.1$\sigma$. 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 $\mu = 1.5 \pm 0.5$. The Higgs boson production cross-section times the $H \rightarrow\ell\ell\gamma$ branching ratio for $m_{\ell\ell} <$ 30 GeV is determined to be 8.7 $^{+2.8}_{-2.7}$ fb.

Item Type: Article
Additional Information: 39 pages in total, author list starting page 23, 5 figures, 1 table, submitted to PLB, All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HIGG-2018-43/
Uncontrolled Keywords: hep-ex, hep-ex
Divisions: Faculty of Science and Engineering > School of Physical Sciences
Depositing User: Symplectic Admin
Date Deposited: 09 Aug 2021 08:02
Last Modified: 19 Oct 2023 09:05
DOI: 10.1016/j.physletb.2021.136412
Open Access URL: https://www.sciencedirect.com/science/article/pii/...
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URI: https://livrepository.liverpool.ac.uk/id/eprint/3132826