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.
Highlights
This paper describes a search for long-lived neutral parpticffiffiles (LLPs), produced by proton-proton interactions at s 1⁄4 8 TeV, that decay to hadronic jets far from the interaction point (IP)
The ATLAS detector [25], which has nearly 4π steradian coverage in solid angle, is a multipurpose detector consisting of an inner tracking detector embedded in a superconducting solenoid, electromagnetic and hadronic calorimeters (ECal and HCal), and a muon spectrometer incorporating magnetic fields produced by three superconducting, air-core toroidal magnets each comprised of eight coils
The distribution of reconstructed vertex positions from K0S decays is determined for both the data and simulated multijet samples, and the distributions are normalized such that the same number of vertices are reconstructed inside the beam pipe
Summary
This paper describes a search for long-lived neutral parpticffiffiles (LLPs), produced by proton-proton interactions at s 1⁄4 8 TeV, that decay to hadronic jets far from the interaction point (IP). This work significantly extends the cτ range of the ATLAS search for a lived neutral particles laitghpt ffisffisc1⁄4al7arTbeoVsoinn decaying 1.94 fb−1 to of long2011 proton-proton collision data at the LHC [23] that covered the cτ region 1–20 m. It extends the range of proper lifetimes excluded by a recent ATLAS analysis [24], which uses the same scalar boson model and mass points but focuses on displaced decays in the hadronic calorimeter
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