Enabling searches for long-lived particles at a future 10 TeV Muon Collider

TL;DR

This paper explores the detection of long-lived particles at a future 10 TeV Muon Collider, highlighting the need to relax timing constraints to improve sensitivity to new physics signals.

Contribution

It demonstrates that loosening hit-timing requirements can enhance detection of long-lived particles, providing design recommendations for future collider detectors.

Findings

Looser timing cuts recover sensitivity to particles near half the collision energy.

Expanding time acceptance improves detection of slow-moving, long-lived particles.

Recommendations for tracker design to optimize long-lived particle searches.

Abstract

Muon Colliders offer fantastic opportunities to explore new phenomena at the energy frontier. However, beam-induced-backgrounds from muon decays pose significant challenges for detector design, readout, and reconstruction. Previous detector studies have employed stringent hit-timing requirements to reduce occupancy to manageable levels with negligible efficiency loss for prompt Standard Model particles. In the spirit of maximizing discovery potential, we investigate the capability of detecting meta-stable charged long-lived particles at a 10 TeV Muon Collider. As a benchmark, we consider a Gauge Mediated Supersymmetry Breaking (GMSB) model in which the stau is long-lived and can be identified as a high momentum, slowly moving track. We find that nominal hit-timing selections are too restrictive, and investigate the impact of looser requirements. We demonstrate that it is possible to recover sensitivity to particles with masses close to $\sqrt{s}/2$ by expanding time acceptance, and provide recommendations to further improve tracker design and track reconstruction.