| ATLAS Note | |
| Report number | ATLAS-CONF-2021-002 |
| Title | Evidence for Higgs boson decays to a low-mass dilepton system and a photon in $pp$ collisions at $\sqrt{s}$ = 13 TeV with the ATLAS detector |
| Corporate Author(s) | The ATLAS collaboration |
| Collaboration | ATLAS Collaboration |
| Publication | 2021 |
| Imprint | 02 Feb 2021 |
| Number of pages | mult. |
| Note | All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/CONFNOTES/ATLAS-CONF-2021-002 |
| Subject category | Particle Physics - Experiment |
| Accelerator/Facility, Experiment | CERN LHC ; ATLAS |
| 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 $H\to\ell\ell\gamma$ 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 $8.7 ^{+2.8}_{-2.7} \text{fb}$. |
| Related document | superseded by: CERN-EP-2021-035 |
Corresponding record in: Inspire
Record created 2021-02-02, last modified 2021-04-19
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