Observation of collider muon neutrinos with the SND@LHC experiment

Abstract: We report the direct observation of muon neutrino interactions with the SND@LHC detector at the Large Hadron Collider. A data set of proton-proton collisions at $\sqrt{s} = 13.6\,$TeV collected by SND@LHC in 2022 is used, corresponding to an integrated luminosity of 36.8$\,\rm{fb}^{-1}$. The search is based on information from the active electronic components of the SND@LHC detector, which covers the pseudo-rapidity region of $7.2 < \eta < 8.4$, inaccessible to the other experiments at the collider. Muon neutrino candidates are identified through their charged-current interaction topology, with a track propagating through the entire length of the muon detector. After selection cuts, 8 $\nu_\mu$ interaction candidate events remain with an estimated background of 0.076 events, yielding a significance of seven standard deviations for the observed $\nu_\mu$ signal.