Particle Physics in Birmingham

Particle Physics Seminar

Wednesday 19th April 2023 at 13:30

(coffee served at 1315)

Exclusive decays of the Higgs and Z bosons to a meson and a photon at ATLAS

Robert Ward (Birmingham University)


In the Standard Model (SM) the mass generation of fermions is implemented through Yukawa couplings to the Higgs boson. For quarks, direct evidence exists only for the third-generation couplings, and direct searches for inclusive decays of the Higgs boson to lighter generations are challenging due to large QCD backgrounds at the LHC. With their distinct experimental signature, exclusive radiative decays of the Higgs boson to a meson and a photon, complemented by searches for analogous decays of the Z boson, offer an alternative probe of quark Yukawa couplings. Moreover, these decays provide an opportunity to investigate physics beyond-the-SM, as many such theories predict branching fractions significantly modified from the SM expectation. This seminar will cover the results of the latest searches from the ATLAS experiment, including for the Higgs and Z boson decays to a quarkonium state and a photon, an omega meson and a photon, and the flavour-changing Higgs boson decay to a K* meson and a photon.