Evidence for the dimuon decay of the Higgs boson in pp collisions with the ATLAS detector

A search for the dimuon decay of the Higgs boson is presented based on pp collision data recorded by ATLAS during Run 3 of the Large Hadron Collider, corresponding to an integrated luminosity of 165 fb${}^{-1}$ at $\sqrt{s}=13.6$ TeV. To enhance the sensitivity, the results are combined with those from Run 2. An excess of events over the background is observed with a significance of $3.4\sigma$ ($2.5\sigma$ expected). The best-fit signal strength is $\mu =1.4\pm 0.4$. This result provides evidence for the $H\to \mu \mu$ decay with ATLAS data and offers a direct probe of the Higgs-boson Yukawa coupling to second-generation fermions.