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