Karlsruhe 2024 – scientific programme

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T: Fachverband Teilchenphysik

T 20: Higgs 1 (boson final states)

T 20.8: Talk

Monday, March 4, 2024, 17:45–18:00, Geb. 30.41: HS 2

Searches for Exclusive Higgs and Vector Boson Decays to a Meson and a Photon at ATLAS — •Robert Ward — Universität Hamburg

In the Standard Model (SM) the mass generation of fermions is implemented through Yukawa couplings to the Higgs boson. Experimental evidence exists for the Higgs boson couplings to second and third generation leptons through its decay to muon and tau pairs, but for quarks direct evidence exists only for the third-generation couplings. Direct searches for inclusive decays of the Higgs boson to lighter quarks are challenging due to large QCD backgrounds at the LHC.

With their distinct experimental signature, radiative decays of the Higgs boson to a meson and a photon may offer an alternative probe of quark Yukawa couplings. Moreover, these decays provide an opportunity to investigate physics beyond-the-SM, where significantly modified branching fractions from the SM expectation are predicted, as well as the existence of potential quark-flavour-violating couplings of the Higgs and Z bosons. This talk will summarise searches for rare exclusive Higgs boson decays to a meson and a photon performed by the ATLAS experiment using the √s = 13 TeV dataset, along with searches for related decays of the massive vector bosons. These searches use dedicated triggers which were in operation throughout Run 2 of the LHC, as well as novel non-parametric data-driven techniques to model the backgrounds.

Keywords: Higgs boson; Vector boson; Rare decays; ATLAS