Long-Lived Particles at the Energy Frontier: The MATHUSLA Physics Case
Creators: name: Curtin, David
name: Drewes, Marco
name: McCullough, Matthew
name: Meade, Patrick
name: Mohapatra, Rabindra N.
name: Shelton, Jessie
name: Shuve, Brian
name: Accomando, Elena
name: Alpigiani, Cristiano
name: Antusch, Stefan
name: Arteaga-Velázquez, Juan Carlos
name: Batell, Brian
name: Bauer, Martin
name: Blinov, Nikita
name: Caballero-Mora, Karen Salomé
name: Chang, Jae Hyeok
name: Chun, Eung Jin
name: Co, Raymond T.
name: Cohen, Timothy
name: Cox, Peter
name: Craig, Nathaniel
name: Csáki, Csaba
name: Cui, Yanou
name: D'Eramo, Francesco
name: Rose, Luigi Delle
name: Dev, P. S. Bhupal
name: Dienes, Keith R.
name: Dror, Jeff A.
name: Essig, Rouven
name: Evans, Jared A.
name: Evans, Jason L.
name: Tellez, Arturo Fernández
name: Fischer, Oliver
name: Flacke, Thomas
name: Fradette, Anthony
name: Frugiuele, Claudia
name: Fuchs, Elina
name: Gherghetta, Tony
name: Giudice, Gian F.
name: Gorbunov, Dmitry
name: Gupta, Rick S.
name: Hagedorn, Claudia
name: Hall, Lawrence J.
name: Harris, Philip
name: Helo, Juan Carlos
name: Hirsch, Martin
name: Hochberg, Yonit
name: Hook, Anson
name: Ibarra, Alejandro
name: Ipek, Seyda
name: Jung, Sunghoon
name: Knapen, Simon
name: Kuflik, Eric
name: Liu, Zhen
name: Lombardo, Salvator
name: Lubatti, H. J.
name: McKeen, David
name: Molinaro, Emiliano
name: Moretti, Stefano
name: Nagata, Natsumi
name: Neubert, Matthias
name: No, Jose Miguel
name: Olaiya, Emmanuel
name: Perez, Gilad
name: Peskin, Michael E.
name: Pinner, David
name: Pospelov, Maxim
name: Reece, Matthew
name: Robinson, Dean J.
name: Cahuantzi, Mario Rodríguez
name: Santonico, Rinaldo
name: Schlaffer, Matthias
name: Shepherd-Themistocleous, Claire H.
name: Spray, Andrew
name: Stolarski, Daniel
name: Vasquez, Martin A. Subieta
name: Sundrum, Raman
name: Thamm, Andrea
name: Thomas, Brooks
name: Tsai, Yuhsin
name: Tweedie, Brock
name: West, Stephen M.
name: Young, Charles
name: Yu, Felix
name: Zaldivar, Bryan
name: Zhang, Yongchao
name: Zurek, Kathryn
name: Zurita, José
Publisher: name: arXiv
Year: 2018
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: We examine the theoretical motivations for long-lived particle (LLP) signals at the LHC in a comprehensive survey of Standard Model (SM) extensions. LLPs are a common prediction of a wide range of theories that address unsolved fundamental mysteries such as naturalness, dark matter, baryogenesis and neutrino masses, and represent a natural and generic possibility for physics beyond the SM (BSM). In most cases the LLP lifetime can be treated as a free parameter from the $μ$m scale up to the Big Bang Nucleosynthesis limit of $\sim 10^7$m. Neutral LLPs with lifetimes above $\sim$ 100m are particularly difficult to probe, as the sensitivity of the LHC main detectors is limited by challenging backgrounds, triggers, and small acceptances. MATHUSLA is a proposal for a minimally instrumented, large-volume surface detector near ATLAS or CMS. It would search for neutral LLPs produced in HL-LHC collisions by reconstructing displaced vertices (DVs) in a low-background environment, extending the sensitivity of the main detectors by orders of magnitude in the long-lifetime regime. In this white paper we study the LLP physics opportunities afforded by a MATHUSLA-like detector at the HL-LHC. We develop a model-independent approach to describe the sensitivity of MATHUSLA to BSM LLP signals, and compare it to DV and missing energy searches at ATLAS or CMS. We then explore the BSM motivations for LLPs in considerable detail, presenting a large number of new sensitivity studies. While our discussion is especially oriented towards the long-lifetime regime at MATHUSLA, this survey underlines the importance of a varied LLP search program at the LHC in general. By synthesizing these results into a general discussion of the top-down and bottom-up motivations for LLP searches, it is our aim to demonstrate the exceptional strength and breadth of the physics case for the construction of the MATHUSLA detector.
description: 213 pages, 73 figures. Extended Section 2 to add more detailed discussion of LLP reconstruction and analysis, and background rejection. Updated comparison of MATHUSLA RH neutrino sensitivity to other experiments. Updated analysis of long-lived ALPs produced in weak-scale processes and decaying to jets. Various clarifications, fixed typos, and added references. Results and conclusions unchanged