Search for light neutral particles decaying promptly into collimated pairs of electrons or muons in pp collisions at s = 13 TeV with the ATLAS detector

Summary, in English

A search for a dark photon, a new light neutral particle, which decays promptly into collimated pairs of electrons or muons is presented. The search targets dark photons resulting from the exotic decay of the Standard Model Higgs boson, assuming its production via the dominant gluon-gluon fusion mode. The analysis is based on 140fb-1 of data collected with the ATLAS detector at the Large Hadron Collider from proton-proton collisions at a center-of-mass energy of 13 TeV. Events with collimated pairs of electrons or muons are analysed and background contributions are estimated using data-driven techniques. No significant excess in the data above the Standard Model background is observed. Upper limits are set at 95% confidence level on the branching ratio of the Higgs boson decay into dark photons between 0.001% and 5%, depending on the assumed dark photon mass and signal model. © The Author(s) 2025.

• Author: G. Aad; T.P.A. Åkesson; K.S.V. Astrand; C. Doglioni; P.A. Ekman; V. Hedberg; H. Herde; B. Konya; E. Lytken; R. Poettgen; O. Smirnova; E.J. Wallin; L. Zwalinski
• Department/s: Particle and nuclear physics; eSSENCE: The e-Science Collaboration; Department of Physics
• Publishing year: 2025
• Language: English
• Publication/Series: European Physical Journal C
• Volume: 85
• Issue: 3
• Links: http://dx.doi.org/10.1140/epjc/s10052-025-13916-5
• Document type: Journal article
• Publisher: Springer Nature
• Topic: Subatomic Physics
• Keywords: Colliding beam accelerators; Electrons; Hadrons; Linear accelerators; Photons; Positive ions; A-center; ATLAS detectors; Center-of-mass energies; Exotic decay; Large Hadron Collider; Large-hadron colliders; Neutral particles; Proton proton collisions; Standard-model Higgs bosons; The standard model; Bosons
• Status: Published
• ISBN/ISSN/Other: ISSN: 1434-6044