Open Access

First Search for Quirks at the LHC with FASER

Roshan Mammen Abraham¹, Xiaocong Ai ², Saul Alonso Monsalve³, John Anders ⁴, Emma Kate Anderson⁵, Akitaka Ariga ^6,7, Tomoko Ariga ⁸, Jeremy Atkinson ⁶, Florian U. Bernlochner ⁹ et al. (FASER Collaboration)

Florian U. Bernlochner ⁹, Jianming Bian ¹, Tobias Boeckh ⁹, Eliot Bornand ¹⁰, Jamie Boyd ⁵, Lydia Brenner ¹¹, Angela Burger ¹², Franck Cadoux¹⁰, Haichuan Cao ¹³, Roberto Cardella ¹⁰, David W. Casper ¹, Charlotte Cavanagh ³, Shiyang Chen ¹³, Xin Chen ¹³, Xing Cheng ¹³, Dhruv Chouhan ⁹, Andrea Coccaro ¹⁴, Fabio Cufino ³, Stephane Débieux¹⁰, Ansh Desai ¹⁵, Sergey Dmitrievsky ¹⁶, Radu Dobre ¹⁷, Monica D’Onofrio⁴, Sinead Eley ⁴, Yannick Favre¹⁰, Jonathan L. Feng ¹, Carlo Alberto Fenoglio¹⁰, Didier Ferrere ¹⁰, Max Fieg ¹⁸, Wissal Filali ⁹, Elena Firu ¹⁷, Haruhi Fujimori ⁷, Edward Galantay ^10,5, Stephen Gibson ¹⁹, Sergio Gonzalez-Sevilla ¹⁰, Yuri Gornushkin ¹⁶, Yotam Granov ²⁰, Jinjing Gu ¹³, Carl Gwilliam ⁴, Elie Hammou ¹¹, Daiki Hayakawa ⁷, Michael Holzbock ⁵, Shih-Chieh Hsu ²¹, Zhen Hu ¹³, Giuseppe Iacobucci ¹⁰, Tomohiro Inada ⁸, Luca Iodice ¹⁰, Sune Jakobsen ⁵, Cesar Jesus-Valls ⁵, Arash Jofrehei ¹⁰, Hans Joos ⁵, Enrique Kajomovitz ²⁰, Alex Keyken ¹⁹, Felix Kling ⁹, Daniela Köck¹⁵, Pantelis Kontaxakis ¹⁰, Jelle Koorn ¹¹, Umut Kose ³, Peter Krack ¹¹, Susanne Kuehn ⁵, Thanushan Kugathasan ¹⁰, Sebastian Laudage ⁹, Lorne Levinson ²², Botao Li ³, Jinmian Li ²³, Jiaxi Liu ¹, Jinfeng Liu ¹³, Yi Liu ², Margaret S. Lutz ⁵, Joern Mahlstedt ⁹, Toni Mäkelä¹, Yasuhiro Maruya ⁸, Anna Mascellani ³, Lawson McCoy ¹, Josh McFayden ²⁴, Andrea Pizarro Medina¹⁰, Hiroaki Menjo ²⁵, Théo Moretti ¹⁰, Toshiyuki Nakano ²⁵, Laurie Nevay ⁵, Ken Ohashi ⁷, Hidetoshi Otono ⁸, Lorenzo Paolozzi ^10,5, Annabelle Parry ^4,5, Pawan Pawan ⁴, Junle Pei ²⁶, Brian Petersen ⁵, Titi Preda ¹⁷, Markus Prim ⁹, Junkai Qin ¹³, Michaela Queitsch-Maitland ²⁷, Juan Rojo ¹¹, Hiroki Rokujo ⁸, André Rubbia ³, Osamu Sato ²⁵, Paola Scampoli ^28,6, Kristof Schmieden ⁹, Matthias Schott ⁹, Cristiano Sebastiani ⁵, Anna Sfyrla ¹⁰, Davide Sgalaberna ³, Mansoora Shamim ⁵, Yosuke Takubo ²⁹, Kakeru Tanaka ⁸, Simon Thor ³, Eric Torrence ¹⁵, Serhan Tufanli ⁶, Oscar Ivan Valdes Martinez²⁷, Svetlana Vasina ¹⁶, Emanuele Villa ³, Benedikt Vormwald ⁵, Chi Wang ¹³, Yuxiao Wang ¹³, Eli Welch ¹, Aaron White ⁵, Monika Wielers ³⁰, Benjamin James Wilson²⁷, Zhongyi Wu ¹, Yue Xu ²¹, Heng Yang ¹³, Lekai Yao ¹³, Daichi Yoshikawa ⁸, Stefano Zambito ¹⁰, Shunliang Zhang ¹³, Yuxuan Zhang ¹³, Xingyu Zhao ³, and Zijian Zhao ¹³ (FASER Collaboration)

¹Department of Physics and Astronomy, University of California, Irvine, California 92697-4575, USA
²School of Physics, Zhengzhou University, Zhengzhou 450001, China
³Institute for Particle Physics, ETH Zürich, Zürich 8093, Switzerland
⁴University of Liverpool, Liverpool L69 3BX, United Kingdom
⁵CERN, CH-1211 Geneva 23, Switzerland
⁶Albert Einstein Center for Fundamental Physics, Laboratory for High Energy Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
⁷Department of Physics, Chiba University, 1-33 Yayoi-cho Inage-ku, 263-8522 Chiba, Japan
⁸Kyushu University, 744 Motooka, Nishi-ku, 819-0395 Fukuoka, Japan
⁹Universität Bonn, Regina-Pacis-Weg 3, D-53113 Bonn, Germany
¹⁰Département de Physique Nucléaire et Corpusculaire, University of Geneva, CH-1211 Geneva 4, Switzerland
¹¹Nikhef National Institute for Subatomic Physics, Science Park 105, 1098 XG Amsterdam, Netherlands
¹²L2IT, Université de Toulouse, CNRS/IN2P3, UPS, Toulouse, France
¹³Department of Physics, Tsinghua University, Beijing, China
¹⁴INFN Sezione di Genova, Via Dodecaneso, 33–16146, Genova, Italy
¹⁵University of Oregon, Eugene, Oregon 97403, USA
¹⁶Affiliated with an international laboratory covered by a cooperation agreement with CERN
¹⁷Institute of Space Science—INFLPR Subsidiary, Bucharest, Romania
¹⁸Theoretical Physics Division, Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA
¹⁹Royal Holloway, University of London, Egham, TW20 0EX, United Kingdom
²⁰Department of Physics and Astronomy, Technion—Israel Institute of Technology, Haifa 32000, Israel
²¹Department of Physics, University of Washington, PO Box 351560, Seattle, Washington 98195-1460, USA
²²Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Rehovot 76100, Israel
²³College of Physics, Sichuan University, Chengdu 610065, China
²⁴Department of Physics and Astronomy, University of Sussex, Sussex House, Falmer, Brighton, BN1 9RH, United Kingdom
²⁵Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
²⁶Institute of Physics, Henan Academy of Sciences, Zhengzhou 450046, China
²⁷University of Manchester, School of Physics and Astronomy, Schuster Building, Oxford Rd, Manchester M13 9PL, United Kingdom
²⁸Dipartimento di Fisica “Ettore Pancini,” Università di Napoli Federico II, Complesso Universitario di Monte S. Angelo, I-80126 Napoli, Italy
²⁹National Institute of Technology (KOSEN), Niihama College, 7-1, Yakumo-cho Niihama, 792-0805 Ehime, Japan
³⁰Particle Physics Department, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot, OX11 0QX, United Kingdom

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Phys. Rev. Lett. 137, 181802 – Published 30 October, 2026

DOI: https://doi.org/10.1103/z156-xk5y

Abstract

We present the first LHC search for quirks, particles with standard model and QCD-like infracolor (IC) interactions. The analysis uses data collected in 2022–2024 by FASER, with a $186 {fb}^{- 1}$ integrated luminosity of proton-proton collisions at a center-of-mass energy $\sqrt{s} = 13.6 TeV$ . Scintillator charge and timing information are used to search for slow pairs of quirks with no QCD color and electric charge $\pm 1$ . No events are seen in this nearly background-free search, resulting in the first exclusion of quirks with masses above the weak scale for IC confinement scales in the broad range of $300 eV < Λ < 100 keV$ .

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Phys. Rev. Lett. 137, 181802– Published 30 October, 2026

Vol. 137, Iss. 18 — 30 October 2026

Received 28 July 2026
Accepted 23 September 2026

DOI: https://doi.org/10.1103/z156-xk5y

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP³.

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First Search for Quirks at the LHC with FASER

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