This document presents the physics case and ancillary studies for the proposed CODEX-b long-lived particle (LLP) detector, as well as for a smaller proof-of-concept demonstrator detector, CODEX-β, to be operated during Run 3 of the LHC. Our development of the CODEX-b physics case synthesizes ‘top-down’ and ‘bottom-up’ theoretical approaches, providing a detailed survey of both minimal and complete models featuring LLPs. Several of these models have not been studied previously, and for some others we amend studies from previous literature: In particular, for gluon and fermion-coupled axion-like particles. We moreover present updated simulations of expected backgrounds in CODEX-b’s actively shielded environment, including the effects of shielding propagation uncertainties, high-energy tails and variation in the shielding design. Initial results are also included from a background measurement and calibration campaign. A design overview is presented for the CODEX-β demonstrator detector, which will enable background calibration and detector design studies. Finally, we lay out brief studies of various design drivers of the CODEX-b experiment and potential extensions of the baseline design, including the physics case for a calorimeter element, precision timing, event tagging within LHCb, and precision low-momentum tracking.
Bibliographical noteFunding Information:
The work of XCV is supported by MINECO (Spain) through the Ramon y Cajal program RYC-2016-20073 and by XuntaGal under the ED431F 2018/01 project. JAE is supported by U.S. Department of Energy (DOE) grant DE-SC0011784. VVG is partially supported by ERC CoG “RECEPT” GA number 724777 within the H2020 framework programme. SK is supported by U.S. DOE grant DE-SC0009988 and the Paul Dirac fund at the Institute for Advanced Study. MP, DR and BN are supported by the U.S. DOE under contract DE-AC02-05CH11231. HR is supported in part by the U.S. DOE under contract DE-AC02-05CH11231. MW is supported by NSF grant PHY-1912836.
Significant parts of this work were performed at: the Aspen Center for Physics, supported by National Science Foundation grant PHY-1607611; the Munich Institute for Astro- and Particle Physics (MIAPP); and the Galileo Galilei Institute for Theoretical Physics. We thank all these institutions for their support and hospitality.
This research used resources of the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility operated under Contract No. DE-AC02-05CH11231. This work has received nancial support from Xunta de Galicia (Centro singular de investigaciòn de Galicia accreditation 2019–2022), by European Union ERDF, and by the “Mara de Maeztu” Units of Excellence program MDM-2016-0692 and the Spanish Research State Agency.
ASJC Scopus subject areas
- Engineering (miscellaneous)
- Physics and Astronomy (miscellaneous)