Abstract
Searches for the exclusive decays of the Higgs boson into D∗γ and of the Z boson into D0γ and K0sγ can probe flavour-violating Higgs and Z boson couplings to light quarks. Searches for these decays are performed with a pp collision data sample corresponding to an integrated luminosity of 136.3 fb−1 collected at s√=13 TeV between 2016-2018 with the ATLAS detector at the CERN Large Hadron Collider. In the D∗γ and D0γ channels, the observed (expected) 95% confidence-level upper limits on the respective branching fractions are B(H→D∗γ)<1.0(1.2)×10−3, B(Z→D0γ)<4.0(3.4)×10−6, while the corresponding results in the K0sγ channel are B(Z→K0sγ)<3.1(3.0)×10−6.