Search for fractionally charged particles in pp collisions using 2011 CMS data

We present a search for a fractionally charged particle, using the $pp$ collision data recorded by CMS at $\sqrt{s} = 7$ TeV in 2011, corresponding to 5.0 \invfb. The search is sensitive to particles with a muon-like signature. % that do not interact through the strong force % that have a lifetime of at least a few nanoseconds, so that a non-negligible fraction of these particles can escape the % detector without decaying. Tracks from fractionally charged particles are identified based on the large number of associated low-ionizing hits. We exclude with 95\% confidence particles with electric charge $\pm 2e/3$ with masses below 330 \gev, and particles of charge $\pm e/3$ below 210 \gev. These are the most stringent collider limits on the production of fractionally charged particles. % This is the most stringent collider limit on the production of % a particle with charge $\pm 2e/3$ and the first collider limit on the % production of a particle with charge $\pm e/3$.