Searching for high speed long-lived charged massive particles at?the LHC

摘要

The conventional way to search for long-lived CHArged Massive Particles (CHAMPs) is to identify slow (small β) tracks using delayed time of flight and high ionization energy loss. But at the 7–14?TeV center of mass energy of the LHC, a CHAMP may be highly boosted (high?β) and therefore look more like a minimum ionizing particle, while for high momentum muons (?500?GeV/c) the radiative effect dominates energy deposition. This suggests a new strategy to search for CHAMPs at the LHC. Using energy deposition from different detector components, we construct a boosted decision tree discriminant to separate high momentum CHAMPs from high momentum muons. This method increases substantially the CHAMP discovery potential and it can be used to distinguish possible di-CHAMP or CHAMP–muon resonance models from di-muon resonance models. We illustrate the new method using a mGMSB model and a recently proposed di-CHAMP model and we give updated CHAMP mass limits for these two models using the results from a recent CDF CHAMP search.