Search for exclusive Higgs and Z boson decays to ωγ and Higgs boson decays to K⁎γ with the ATLAS detector
Abstract
Searches for the exclusive decays of the Higgs boson to an ω meson and a photon or a K⁎ meson and a photon can probe flavour-conserving and flavour-violating Higgs boson couplings to light quarks, respectively. Searches for these decays, along with the analogous Z boson decay to an ω meson and a photon, are performed with a pp collision data sample corresponding to integrated luminosities of up to 134 fb-1 collected at s=13 TeV with the ATLAS detector at the CERN Large Hadron Collider.
The obtained 95% confidence-level upper limits on the respective branching fractions are B(HRIGHTWARDS ARROWωγ)<5.5x10-4, B(HRIGHTWARDS ARROWK⁎γ)<2.2x10-4 and B(ZRIGHTWARDS ARROWωγ)<3.9x10-6. The limits for HRIGHTWARDS ARROWωγ and ZRIGHTWARDS ARROWωγ are 370 times and 140 times the Standard Model expected values, respectively.
The result for ZRIGHTWARDS ARROWωγ corresponds to a two-orders-of-magnitude improvement over the limit obtained by the DELPHI experiment at LEP.