Observation of collider neutrinos without final state muons with the SND@LHC experiment

Abstract: We report the observation of neutrino interactions without final state muons at the LHC, with a significance of 6.4$ \sigma$. A data set of proton-proton collisions at $\sqrt{s}= 13.6$ TeV collected by SND@LHC in 2022 and 2023 is used, corresponding to an integrated luminosity of 68.6 fb$^{-1}$. Neutrino interactions without a reconstructed muon are selected, resulting in an event sample consisting mainly of neutral-current and electron neutrino charged-current interactions in the detector. After selection cuts, 9 neutrino interaction candidate events are observed with an estimated background of 0.32 events.