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

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.