Search for dark photons with the FASER detector at the LHC
H. Abreu, J. K. Anders, C. Antel, A. Ariga, T. Ariga, Jeremy Atkinson, F. U. Bernlochner, Tobias Boeckh, Jamie Boyd, L. Brenner, F. Cadoux, D. Casper, Charlotte Cavanagh, X. Chen, A. Coccaro, M. D’Onofrio, Ansh Desai, Sergey Dmitrievsky, C. Dozen, Yannick Favre, D. E. Fellers, Jonathan L. Feng, Carlo Alberto Fenoglio, D. Ferrère, Iftah Galon, 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, Sam Meehan, Matteo Milanesio, Théo Moretti, Magdalena Münker, Mitsuhiro Nakamura, Toshiyuki Nakano, F. Neuhaus, Laurie Nevay, K. Ohashi, H. Otono, Hao Pang, L. Paolozzi, Brian Petersen, M. T. Prim, M. Queitsch-Maitland, Hiroki Rokujo, Elisa Ruiz-Chóliz, Jorge Sabater-Iglesias, Jakob Salfeld-Nebgen, Osamu Sato, P. Scampoli, K. Schmieden, M. Schott, A. Sfyrla, Savannah Shively, Y. Takubo, Noshin Tarannum, O. Theiner, E. Torrence, Sebastian Trojanowski, S. Vasina, B. Vormwald, D. Wang, Eli Welch, Samuel Zahorec, S. Zambito
Abstract
The FASER experiment at the LHC is designed to search for light, weakly-interacting particles produced in proton-proton collisions at the ATLAS interaction point that travel in the far-forward direction. The first results from a search for dark photons decaying to an electron-positron pair, using a dataset corresponding to an integrated luminosity of 27.0 fb−1 collected at center-of-mass energy s=13.6 TeV in 2022 in LHC Run 3, are presented. No events are seen in an almost background-free analysis, yielding world-leading constraints on dark photons with couplings ϵ∼2×10−5−1×10−4 and masses ∼17MeV−70MeV. The analysis is also used to probe the parameter space of a massive gauge boson from a U(1)B−L model, with couplings gB−L∼5×10−6−2×10−5 and masses ∼15MeV−40MeV excluded for the first time.