Hi Oliver,
I will check better tomorrow, but my recollection is that the resolution
on the signal improved (our signal) while there was a broadening of the
distribution for the background which we pretty much liked. I think it is
due to the fact that we are throughing away almost all Kls, which is good
for our signal, but not for yours. As attempt you can try and remove the
cuts that are against Kl (LAT and S9S25) and see if you recover the
resolution you want.

Riccardo Faccini
Universita' "La Sapienza" & I.N.F.N. Roma
tel  +39/06/49914457 Fax.: +39/06/4957697
Univ. La Sapienza. 2,Ple Aldo Moro, I-00185 Roma Dipartimento di Fisica

"We need serenity to accept what we cannot change, courage to change what
we can and wisdom to distinguish between the two" [R. Kiplin, allegedly]

On Wed, 2 Apr 2003, Oliver Buchmueller wrote:

> Hi,
> in my attempt to adopt the track and neutral selection from the vub
> measurement for the mass moments analysis I realized that there has
> been a significant broadening of the missing mass distribution
> taken place between old vub selection (middle of last year) and
> the new one. This broadening can be seen by comparing missing mass
> plots in BAD 347 (v4 page 45) and BAD 540 (v8 page 57). Using the
> b->u enh. distribution one finds a broadening of roughly 50% off
> the new missing mass distribution with respect to the old one
> (it should also be noted that there is virtually no difference
> concerning the quality of the data MC comparison for this plots?!)
> This large increase in MM2 will certainly have a severe impact on
> the mass resolution of Mx and will probably not be acceptable
> for the new direct measurement approach (slops of the calibration
> curves will get significantly worse due to the loss of information
> caused by the new vub track and neutral selection).
> Does someone know the reason for this  broadening ... it almost
> looks like that there are cuts at work which throw away useful
> information in the event ... or do I misunderstand something here?
> Thanks for your help,
> Oliver