Search for short- and long-lived axion-like particles in $H\to aa\to 4\gamma$ decays with the ATLAS experiment at the LHC

Abstract

Presented is the search for anomalous Higgs boson decays into two axion-like particles (ALPs) using the full Run 2 data set of 140 fb${}^{-1}$ of proton-proton collisions at a centre-of-mass energy of 13 TeV recorded by the ATLAS experiment. The ALPs are assumed to decay into two photons, providing sensitivity to recently proposed models that could explain the $(g-2{)}_{\mu }$ discrepancy. This analysis covers an ALP mass range from 100 MeV to 62 GeV and ALP-photon couplings in the range $10^{-5}{\text{TeV}}^{-1}<C_{a\gamma \gamma }/\Lambda <1{\text{TeV}}^{-1}$, and therefore includes signatures with significantly displaced vertices and highly collinear photons. No significant excess of events above the Standard Model background is observed. Upper limits at 95% confidence level are placed on the branching ratio of the Higgs boson to two ALPs in the four-photon final state, and are in the range of $10^{-5}$ to $3\times 10^{-2}$, depending on the hypothesized ALP mass and ALP-photon coupling strength.

45 pages in total, author list starting page 28, 9 figures, 2 tables, published in EPJc. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HDBS-2019-19/

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Cited by in corpus (10)

• Rare and exclusive few-body decays of the Higgs, Z, W bosons, and the top quark
• The Muon Magnetic Moment and Physics Beyond the Standard Model
• Leptophilic Axion-like Particles at Forward Detectors
• Search for new resonances decaying to pairs of merged diphotons in proton-proton collisions at $\sqrt{s}$ = 13 TeV
• The LHC as an Axion-Photon Collider
• Concurrent Exploration of Axion-Like Particle Interactions with Gauge Bosons at the LHC
• Rare few-body decays of the Standard Model Higgs boson
• Search for Higgs boson decays into a $Z$ boson and a light hadronically decaying resonance in $pp$ collisions at $\sqrt{s}$=13 TeV with the ATLAS detector
• Search for Higgs boson exotic decays into Lorentz-boosted light bosons in the four-$\tau$ final state at $\sqrt{s}=13$ TeV with the ATLAS detector
• Di-decay signature of new physics particles at intensity frontier experiments