Expression of interest for the CODEX-b detector
Giulio Aielli, Eli Ben-Haim, Roberto Cardarelli, Matthew John Charles, Xabier Cid Vidal, Victor Coco, Biplab Dey, Raphael Dumps, Jared A. Evans, George Gibbons, Olivier Le Dortz, Vladimir V. Gligorov, Philip Ilten, Simon Knapen, Jongho Lee, Saul López Soliño, Benjamin Nachman, Michele Papucci, Francesco Polci, Robin Quessard, Harikrishnan Ramani, Dean J. Robinson, Heinrich Schindler, Michael D. Sokoloff, Paul Swallow, Riccardo Vari, Nigel Watson, Mike Williams
Abstract
Abstract 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- $$\beta $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>β</mml:mi> </mml:math> , 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- $$\beta $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>β</mml:mi> </mml:math> 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.