Charm muoproduction with a small-angle veto

Abstract

In dimuon production $\ensuremath{\mu}N\ensuremath{\rightarrow}\ensuremath{\mu}\ensuremath{\mu}X$ the signal from associated charm production with semileptonic charm decay is likely to be swamped by background from electromagnetic and hadronic trimuons where one muon is lost through small-angle acceptance cuts. However, if the small-angle cut is replaced by a small-angle muon veto, the calculated background drops well below the expected charm dimuon signal. For trimuon production $\ensuremath{\mu}N\ensuremath{\rightarrow}\ensuremath{\mu}\ensuremath{\mu}\ensuremath{\mu}X$ there is little difference between cut and veto situations; the charm signal is much smaller than background but can be separated by energy and invariant-mass cuts.