Hi, here are a couple of plots showing the mm2 distribution for the resonant signal decays: http://www.slac.stanford.edu/~menges/Vub/Fitter.new/mm2.eps http://www.slac.stanford.edu/~menges/Vub/Fitter.new/mm2_zoom.eps The different final states are, as expected, peaking around zero but not very sharp. A tight cut will not help very much to separate good reconstructed resonances from not so good reconstructed ones.. Cheers, Wolfgang ----------------------------------------------------------------------------- Wolfgang Menges Queen Mary, University of London SLAC, MS 35 Mile End Road 2575 Sand Hill Road London, E1 4NS, UK Menlo Park, CA 94025, USA ++44 20 7882 3753 ++1 650 926 8503 [log in to unmask] -----------------------------------------------------------------------------