Anomalous Production of High-Energy Muons ine+e−Collisions at 4.8 GeV

Abstract

In view of the possible production of heavy leptons or charmed states in $e^{+}{e}^{-}$ collisions, we searched for anomalous muons with momenta $p_{\mu }\gtrsim 1$ GeV/c. The inclusive cross section for $n_{\mathrm{ch}}>~3$ has an upper limit of 96 pb (assuming isotropy). For $n_{\mathrm{ch}}=2\mathrm{}$ and noncoplanarity > 20°, an excess of muonic events is observed, corresponding to ${\left(\frac{d\sigma }{d\Omega }\right)|}_{90°}={23}_{-9\mathrm{}}^{+12\mathrm{}}$ pb/sr; the probability that known processes produce the observed events is 2×${10}^{-4\mathrm{}}$.