Abstract
A search for heavy long-lived multi-charged particles is performed using the ATLAS detector at the LHC. Data with an integrated luminosity of 36.1 fb$^{-1}$ collected in 2015 and 2016 from proton-proton collisions at $\sqrt{s}$ = 13 TeV are examined. Particles producing anomalously high ionization, consistent with long-lived massive particles with electric charges from |q|=2e to |q|=7e, are searched for. No events are observed, and 95% confidence level cross-section upper limits are interpreted as lower mass limits for a Drell-Yan production model. Multi-charged particles with masses between 50 GeV and 980-1220 GeV (depending on their electric charge) are excluded.
Highlights
This article describes a search multicharged particles (MCPs) in pfoffisffir1⁄4h1ea3vTyeVlonpgr-olitvoendproton collision data collected in 2015 and 2016 by the ATLAS detector at the CERN Large Hadron Collider (LHC)[1]
The time interval with the signal above the threshold is approximately proportional to the ionization charge and its dynamic range corresponds to 8.5 times (1.5 times for the insertable B-layer (IBL)) the average charge released by a minimum-ionizing particle (MIP) if its track is normal to the silicon detectors and it deposits all its ionization charge in a single pixel
Charged-particle trajectories are reconstructed using standard algorithms. Since these algorithms assume particles with unit electric charge, the momenta of MCPs are underestimated by a factor z, as the track curvature is proportional to pT=z
Summary
This article describes a search multicharged particles (MCPs) in pfoffisffir1⁄4h1ea3vTyeVlonpgr-olitvoendproton collision data collected in 2015 and 2016 by the ATLAS detector at the CERN Large Hadron Collider (LHC). A purely electromagnetic coupling, proportional to the electric charge of the MCPs, is assumed for the production model In this search the MCPs are assumed to live long enough to traverse the entire ATLAS detector without decaying, and the analysis exploits their muonlike signature, making the muon trigger a natural choice. They are highly ionizing, and generate an abnormally large ionization signal, dE=dx, which leads to their significant slowdown. The background expected from the SM processes (largely high-pT muons) is estimated using a data-driven technique
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