First Direct Observation of Collider Neutrinos with FASER at the LHC
H. Abreu, J. K. Anders, C. Antel, A. Ariga, T. Ariga, Jeremy Atkinson, F. U. Bernlochner, Tobias Blesgen, Tobias Boeckh, Jamie Boyd, L. Brenner, F. Cadoux, D. Casper, Charlotte Cavanagh, X. Chen, A. Coccaro, Ansh Desai, Sergey Dmitrievsky, M. D’Onofrio, Yannick Favre, D. E. Fellers, Jonathan L. Feng, Carlo Alberto Fenoglio, D. Ferrère, S. M. Gibson, S. González-Sevilla, Y. Gornushkin, C. B. Gwilliam, D. Hayakawa, S.‐C. Hsu, Z. Hu, G. Iacobucci, Tomohiro Inada, S. Jakobsen, Hans Ludwig Joos, E. Kajomovitz, H. Kawahara, Alex Keyken, Felix Kling, Daniela Köck, U. Köse, Rafaella Kotitsa, S. Kuehn, H. P. Lefebvre, L. J. Levinson, K. Li, Jinfeng Liu, J. C. MacDonald, Chiara Magliocca, Fulvio Martinelli, J. A. Mcfayden, Matteo Milanesio, D. Mladenov, Théo Moretti, Magdalena Münker, Mitsuhiro Nakamura, Toshiyuki Nakano, M. Nessi, F. Neuhaus, Laurie Nevay, H. Otono, Hao Pang, L. Paolozzi, Brian Petersen, F. Pietropaolo, M. T. Prim, M. Queitsch-Maitland, F. Resnati, Hiroki Rokujo, Elisa Ruiz-Chóliz, Jorge Sabater-Iglesias, Osamu Sato, P. Scampoli, K. Schmieden, M. Schott, A. Sfyrla, Savannah Shively, Y. Takubo, Noshin Tarannum, O. Theiner, E. Torrence, S. Tufanli, S. Vasina, B. Vormwald, D. Wang, Eli Welch, S. Zambito
Abstract
We report the first direct observation of neutrino interactions at a particle collider experiment. Neutrino candidate events are identified in a 13.6 TeV center-of-mass energy pp collision dataset of 35.4 fb^{-1} using the active electronic components of the FASER detector at the Large Hadron Collider. The candidates are required to have a track propagating through the entire length of the FASER detector and be consistent with a muon neutrino charged-current interaction. We infer 153_{-13}^{+12} neutrino interactions with a significance of 16 standard deviations above the background-only hypothesis. These events are consistent with the characteristics expected from neutrino interactions in terms of secondary particle production and spatial distribution, and they imply the observation of both neutrinos and anti-neutrinos with an incident neutrino energy of significantly above 200 GeV.