Long-Lived Neutralino NLSPs

TL;DR

This paper explores collider signatures of long-lived neutralino NLSPs decaying to Z bosons and gravitinos, proposing detection strategies at LHC and Tevatron, and enabling precise mass and lifetime measurements.

Contribution

It introduces methods for detecting and analyzing long-lived neutralino NLSPs at colliders, including event reconstruction and parameter space exploration.

Findings

Potential early LHC discovery across a wide lifetime range

Event reconstruction enables accurate neutralino mass and lifetime measurement

Tevatron could discover new physics in delayed Z+MET channel

Abstract

We investigate the collider signatures of heavy, long-lived, neutral particles that decay to charged particles plus missing energy. Specifically, we focus on the case of a neutralino NLSP decaying to Z and gravitino within the context of General Gauge Mediation. We show that a combination of searches using the inner detector and the muon spectrometer yields a wide range of potential early LHC discoveries for NLSP lifetimes ranging from 10^(-1)-10^5 mm. We further show that events from Z(l+l-) can be used for detailed kinematic reconstruction, leading to accurate determinations of the neutralino mass and lifetime. In particular, we examine the prospects for detailed event study at ATLAS using the ECAL (making use of its timing and pointing capabilities) together with the TRT, or using the muon spectrometer alone. Finally, we also demonstrate that there is a region in parameter space where the Tevatron could potentially discover new physics in the delayed Z(l+l-)+MET channel. While our discussion centers on gauge mediation, many of the results apply to any scenario with a long-lived neutral particle decaying to charged particles.