Result of search for low velocity exotic particles

The L3+C experiment, taking advantage of the L3 muon magnetic spectrometer, measured the spatial tracks of charged cosmic ray particles to obtain rigidity as well as velocity. One possible low velocity exotic particle is observed. The existing uncertainties are discussed, and the flux upper limit of the low velocity exotic particles from this observation is deduced based on the assumption of a null observation. The result is 6.2 × 10−10 cm−2.s−1.sr−1 at 90% confidence level in the velocity range from 0.04c to 0.5c.