Search for long-lived, weakly interacting particles that decay to displaced hadronic jets in proton-proton collisions at $\sqrt{s}=8$ TeV with the ATLAS detector

TL;DR

This paper reports a search for long-lived, weakly interacting particles decaying to displaced jets using ATLAS data at 8 TeV, setting new limits on their lifetimes and exploring various theoretical models.

Contribution

It introduces novel techniques for reconstructing displaced decay vertices and provides the first search results for specific models like Z' and Stealth SUSY at the LHC.

Findings

No significant excess observed over background.

Sets the most stringent limits on proper lifetimes to date.

Provides first experimental constraints on Z' and Stealth SUSY models.

Abstract

A search for the decay of neutral, weakly interacting, long-lived particles using data collected by the ATLAS detector at the LHC is presented. This analysis uses the full dataset recorded in 2012: 20.3 fb$^{-1}$ of proton--proton collision data at $\sqrt{s} = 8$ TeV. The search employs techniques for reconstructing decay vertices of long-lived particles decaying to jets in the inner tracking detector and muon spectrometer. Signal events require at least two reconstructed vertices. No significant excess of events over the expected background is found, and limits as a function of proper lifetime are reported for the decay of the Higgs boson and other scalar bosons to long-lived particles and for Hidden Valley $Z^\prime$ and Stealth SUSY benchmark models. The first search results for displaced decays in $Z^\prime$ and Stealth SUSY models are presented. The upper bounds of the excluded proper lifetimes are the most stringent to date.