 |
 |
Hello folks, I have performed a few studies on eoverp=E/P. First I check, on B0 electrons, the agreement between data and MC of E/P for the electron. This is shown in http://www.slac.stanford.edu/~rfaccini/phys/vub/eoverp/comparison7eoverpallcuts.ps after all cuts and in http://www.slac.stanford.edu/~rfaccini/phys/vub/eoverp/comparison7eoverpleptoncuts.ps after lepton cuts They show that there is an offset and a smearing between data and MC, but the effect I was mostly afraid of (tails truncated in data and not in MC) is not present. I checked whether there could be a correlation between the eoverp and mxhadfit or mm2. I could not find any such correlation. For istance in http://www.slac.stanford.edu/~rfaccini/phys/vub/eoverp/eopmm2.eps the dependence with mm2 in data is shown for events in the enriched sample after selection (i.e. those that are thought to have a problem). The slope is consistent with 0. I then checked if the effect is a function of the momentum of the electron in order to be able to extract a rescaling factor for EMC clusters. Figures http://www.slac.stanford.edu/~rfaccini/phys/vub/eoverp/eopplep_data.eps (data) and http://www.slac.stanford.edu/~rfaccini/phys/vub/eoverp/eopplep_mc.eps (MC) show the mean values and resolutions fitted on data and MC in bins of momentum (the momenta are in the label, 1:1.5 means between 1 and 1.5 GeV). The numbers are: momentum data MC range(GeV) peak(%) resolution(%) peak(%) resolution(%) 1-1.5 98.4+/-0.1 2.7+/-0.1 99.30+/-0.06 2.00+/-0.05 1.5-2 98.6+/-0.2 2.7+/-0.1 99.61+/-0.06 2.00+/-0.05 2-2.5 98.5+/-0.2 2.7+/-0.2 99.80+/-0.07 1.97+/-0.06 2.5-3 98.9+/-0.2 2.2+/-0.2 99.82+/-0.10 1.94+/-0.08 There is no clear dependence on momentum, and the overall shift and smearing (in terms of percent) could be used to smear emc clusters and see the impact on the analysis. Of course it would be nicer to know what happens at the lower momenta ... bye ric