# Search for long-lived stopped R-hadrons decaying out-of-time with pp collisions using the ATLAS detector

## TL;DR

This paper reports an updated search for long-lived R-hadrons that stop in the ATLAS detector and decay out-of-time, setting new mass limits for gluinos, top squarks, and bottom squarks based on collision data at 7 and 8 TeV.

## Contribution

It introduces an improved method for detecting out-of-time R-hadron decays and provides new exclusion limits on their masses and lifetimes using LHC data.

## Key findings

- Excluded gluino masses below 832 GeV for certain lifetimes and neutralino mass.
- Excluded top squark and bottom squark masses below 379 GeV and 344 GeV, respectively.
- Set new limits on R-hadron properties based on non-observation of decay events.

## Abstract

An updated search is performed for gluino, top squark, or bottom squark R-hadrons that have come to rest within the ATLAS calorimeter, and decay at some later time to hadronic jets and a neutralino, using 5.0 and 22.9 fb-1 of pp collisions at 7 and 8 TeV, respectively. Candidate decay events are triggered in selected empty bunch crossings of the LHC in order to remove pp collision backgrounds. Selections based on jet shape and muon-system activity are applied to discriminate signal events from cosmic ray and beam-halo muon backgrounds. In the absence of an excess of events, improved limits are set on gluino, stop, and sbottom masses for different decays, lifetimes, and neutralino masses. With a neutralino of mass 100 GeV, the analysis excludes gluinos with mass below 832 GeV (with an expected lower limit of 731 GeV), for a gluino lifetime between 10 microseconds and 1000 s in the generic R-hadron model with equal branching ratios for decays to qqbar+neutralino and gluon+neutralino. Under the same assumptions for the neutralino mass and squark lifetime, top squarks and bottom squarks in the Regge R-hadron model are excluded with masses below 379 and 344 GeV, respectively.