Potential for probing three-body decays of Long-Lived Particles with MATHUSLA

TL;DR

This paper evaluates MATHUSLA's potential to detect and analyze three-body decays of long-lived neutral particles at the LHC, focusing on distinguishing decay types and reconstructing model parameters.

Contribution

It provides a detailed analysis of MATHUSLA's capabilities to identify three-body LLNP decays and differentiate them from two-body decays, advancing detection strategies for new physics.

Findings

MATHUSLA can effectively discriminate between two- and three-body decays.

The detector has potential to reconstruct underlying model parameters.

Analysis enhances understanding of LLNP decay signatures.

Abstract

Several extensions of the Standard Model predict the existence of Long-Lived Neutral Particles (LLNPs) with masses in the multi-GeV range and decay lengths of O(100 m) or longer. These particles could be copiously produced at the LHC, but the decay products cannot be detected with the ATLAS or CMS detectors. MATHUSLA is a proposed large-volume surface detector installed near ATLAS or CMS aimed to probe scenarios with LLNPs which offers good prospects for disentangling the physics underlying two-body decays into visible particles. In this work we focus on LLNP decays into three particles with one of them being invisible, which are relevant for scenarios with low scale supersymmetry breaking, feebly interacting dark matter or sterile neutrinos, among others. We analyze the MATHUSLA prospects to discriminate between two- and three-body LLNP decays, as well as the prospects for reconstructing the underlying model parameters.