Measurement of Direct Muon Production in the Forward Direction

Abstract

Direct muon production in the forward direction in 300-GeV proton-uranium collisions has been measured at Fermilab. The measurements were made for muons with ${P}_{\ensuremath{\perp}}$ less than 400 MeV/c and with momenta of 90 and 150 GeV/c. The values for the $\frac{\ensuremath{\mu}}{\ensuremath{\pi}}$ ratios are $\frac{{\ensuremath{\mu}}^{\ensuremath{-}}}{{\ensuremath{\pi}}^{\ensuremath{-}}}=(1.56\ifmmode\pm\else\textpm\fi{}0.40)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ and $\frac{{\ensuremath{\mu}}^{+}}{{\ensuremath{\pi}}^{+}}=(4.7\ifmmode\pm\else\textpm\fi{}1.1)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ at 90 GeV/c; and $\frac{{\ensuremath{\mu}}^{\ensuremath{-}}}{{\ensuremath{\pi}}^{\ensuremath{-}}}=(3.8\ifmmode\pm\else\textpm\fi{}2.1)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ at 150 GeV/c. The ratio $\frac{{\ensuremath{\mu}}^{+}}{{\ensuremath{\mu}}^{\ensuremath{-}}}$ at 90 GeV/c is 1.05 \ifmmode\pm\else\textpm\fi{} 0.1. The signal is too large to be accounted for by known processes.