Search for Higgs boson decays into a pair of pseudoscalar particles in the γγτhadτhad final state using pp collisions at s = 13 TeV with the ATLAS detector


Aad G., Aakvaag E., Abbott B., Abdelhameed S., Abeling K., Abicht N., ...More

Journal of High Energy Physics, vol.2025, no.3, 2025 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 2025 Issue: 3
  • Publication Date: 2025
  • Doi Number: 10.1007/jhep03(2025)190
  • Journal Name: Journal of High Energy Physics
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, INSPEC, zbMATH, Directory of Open Access Journals, Nature Index
  • Keywords: Hadron-Hadron Scattering
  • Istanbul University Affiliated: Yes

Abstract

A search for exotic decays of the 125 GeV Higgs boson into a pair of new spin-0 particles, H → aa, where one decays into a photon pair and the other into a τ-lepton pair, is presented. Hadronic decays of the τ-leptons are considered and reconstructed using a dedicated tagger for collimated τ-lepton pairs. The search uses 140 fb−1 of proton-proton collision data at a centre-of-mass energy of s = 13 TeV recorded between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider. The search is performed in the mass range of the a boson between 10 GeV and 60 GeV. No significant excess of events is observed above the Standard Model background expectation. Model-independent upper limits at 95% confidence level are set on the branching ratio of the Higgs boson to the γγττ final state, B(H → aa → γγττ), ranging from 0.2% to 2%, depending on the a-boson mass hypothesis.