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arXiv · 2410.10363

Shining Light on the Dark Sector: Search for Axion-like Particles and Other New Physics in Photonic Final States with FASER

FASER collaboration·Roshan Mammen Abraham·Xiaocong Ai·John Anders·Claire Antel·Akitaka Ariga·Tomoko Ariga·Jeremy Atkinson·Florian U. Bernlochner·Emma Bianchi·Tobias Boeckh·Jamie Boyd·Lydia Brenner·Angela Burger·Franck Cadoux·Roberto Cardella·David W. Casper·Charlotte Cavanagh·Xin Chen·Eunhyung Cho·Dhruv Chouhan·Andrea Coccaro·Stephane Débieux·Monica D'Onofrio·Ansh Desai·Sergey Dmitrievsky·Radu Dobre·Sinead Eley·Yannick Favre·Deion Fellers·Jonathan L. Feng·Carlo Alberto Fenoglio·Didier Ferrere·Max Fieg·Wissal Filali·Elena Firu·Edward Galantay·Ali Garabaglu·Stephen Gibson·Sergio Gonzalez-Sevilla·Yuri Gornushkin·Carl Gwilliam·Daiki Hayakawa·Michael Holzbock·Shih-Chieh Hsu·Zhen Hu·Giuseppe Iacobucci·Tomohiro Inada·Luca Iodice·Sune Jakobsen·Hans Joos·Enrique Kajomovitz·Hiroaki Kawahara·Alex Keyken·Felix Kling·Daniela Köck·Pantelis Kontaxakis·Umut Kose·Rafaella Kotitsa·Susanne Kuehn·Thanushan Kugathasan·Lorne Levinson·Ke Li·Jinfeng Liu·Yi Liu·Margaret S. Lutz·Jack MacDonald·Chiara Magliocca·Toni Mäkelä·Lawson McCoy·Josh McFayden·Andrea Pizarro Medina·Matteo Milanesio·Théo Moretti·Mitsuhiro Nakamura·Toshiyuki Nakano·Laurie Nevay·Ken Ohashi·Hidetoshi Otono·Lorenzo Paolozzi·Brian Petersen·Titi Preda·Markus Prim·Michaela Queitsch-Maitland·Hiroki Rokujo·André Rubbia·Jorge Sabater-Iglesias·Osamu Sato·Paola Scampoli·Kristof Schmieden·Matthias Schott·Anna Sfyrla·Davide Sgalaberna·Mansoora Shamim·Savannah Shively·Yosuke Takubo·Noshin Tarannum·Ondrej Theiner·Eric Torrence·Oscar Ivan Valdes Martinez

Abstract

The first FASER search for a light, long-lived particle decaying into a pair of photons is reported. The search uses LHC proton-proton collision data at $\sqrt{s}=13.6~\text{TeV}$ collected in 2022 and 2023, corresponding to an integrated luminosity of $57.7\text{fb}^{-1}$. A model with axion-like particles (ALPs) dominantly coupled to weak gauge bosons is the primary target. Signal events are characterised by high-energy deposits in the electromagnetic calorimeter and no signal in the veto scintillators. One event is observed, compared to a background expectation of $0.44 \pm 0.39$ events, which is entirely dominated by neutrino interactions. World-leading constraints on ALPs are obtained for masses up to $300~\text{MeV}$ and couplings to the Standard Model W gauge boson, $g_{aWW}$, around $10^{-4}$ GeV$^{-1}$, testing a previously unexplored region of parameter space. Other new particle models that lead to the same experimental signature, including ALPs coupled to gluons or photons, U(1)$_B$ gauge bosons, up-philic scalars, and a Type-I two-Higgs doublet model, are also considered for interpretation, and new constraints on previously viable parameter space are presented in this paper.

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FASER collaboration, Roshan Mammen Abraham, Xiaocong Ai, John Anders, Claire Antel, Akitaka Ariga, Tomoko Ariga, Jeremy Atkinson, Florian U. Bernlochner, Emma Bianchi, Tobias Boeckh, Jamie Boyd, Lydia Brenner, Angela Burger, Franck Cadoux, Roberto Cardella, David W. Casper, Charlotte Cavanagh, Xin Chen, Eunhyung Cho, Dhruv Chouhan, Andrea Coccaro, Stephane Débieux, Monica D'Onofrio, Ansh Desai, Sergey Dmitrievsky, Radu Dobre, Sinead Eley, Yannick Favre, Deion Fellers, Jonathan L. Feng, Carlo Alberto Fenoglio, Didier Ferrere, Max Fieg, Wissal Filali, Elena Firu, Edward Galantay, Ali Garabaglu, Stephen Gibson, Sergio Gonzalez-Sevilla, Yuri Gornushkin, Carl Gwilliam, Daiki Hayakawa, Michael Holzbock, Shih-Chieh Hsu, Zhen Hu, Giuseppe Iacobucci, Tomohiro Inada, Luca Iodice, Sune Jakobsen, Hans Joos, Enrique Kajomovitz, Hiroaki Kawahara, Alex Keyken, Felix Kling, Daniela Köck, Pantelis Kontaxakis, Umut Kose, Rafaella Kotitsa, Susanne Kuehn, Thanushan Kugathasan, Lorne Levinson, Ke Li, Jinfeng Liu, Yi Liu, Margaret S. Lutz, Jack MacDonald, Chiara Magliocca, Toni Mäkelä, Lawson McCoy, Josh McFayden, Andrea Pizarro Medina, Matteo Milanesio, Théo Moretti, Mitsuhiro Nakamura, Toshiyuki Nakano, Laurie Nevay, Ken Ohashi, Hidetoshi Otono, Lorenzo Paolozzi, Brian Petersen, Titi Preda, Markus Prim, Michaela Queitsch-Maitland, Hiroki Rokujo, André Rubbia, Jorge Sabater-Iglesias, Osamu Sato, Paola Scampoli, Kristof Schmieden, Matthias Schott, Anna Sfyrla, Davide Sgalaberna, Mansoora Shamim, Savannah Shively, Yosuke Takubo, Noshin Tarannum, Ondrej Theiner, Eric Torrence, Oscar Ivan Valdes Martinez. 2024-10-14. Shining Light on the Dark Sector: Search for Axion-like Particles and Other New Physics in Photonic Final States with FASER. https://arxiv.org/abs/2410.10363

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