Vub measurement using recoil of fully reconstructed Bs


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Daniele del Re <[log in to unmask]>
15 Mar 2002 07:58:14 -0800 (PST)Fri, 15 Mar 2002 07:58:14 -0800 (PST)
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Something to discuss today:

1) look at my previous posting about generic MC fit

2) I started to look at data. These are the "blinded" plots (but don't do
any subtraction from the number in the Urs presentation ;-) ):

(to be compared with the generic MC

the shape for the background is pretty similar to the generic one and the
result of the fit seems to be fine. The only problem is related to the
"other" component which is negligible here. We have to study in detail
this effect.

3) I calculated the extra correction due to the different efficiency
of the cut on pstarof the lepton between Vub and Vcb events. The total
correction factor is 1.137.
I split the correction in two factors:

  different spectrum                        1.09

  wrong sign correlation due to cascades    1.04

4) the total number of events we have on data at the moment has large
discrepancies with the one I got using CPFramework and objectivity reduced
collections. We have to invetigate this problem (very high priority).

5) MC statistics: at the moment the Cocktail MC corresponds to ~350 fb-1
but if we require a coherent mixture of B0 and B+ this number becomes
160fb-1. Using the second sample to take the background shapes
we introduce a large systematic effect (since the stat error is due mainly
to the number of bkg events we could have a syst. effect that is not
far from 50% of the stat error)


On Thu, 14 Mar 2002, Urs Langenegger wrote:

> Hoi,
> we'll have a meeting on Friday, 03/15/02, at 8:00 am PST. Those at
> SLAC can meet in the Group C conference room.
> Connection details:
>   Call 1-510-647-3480, press 1, enter 191055# and follow the instructions to attend.
> We'll flash  Concezio in  Bremen. Please let  me know if  someone else
> needs to be flashed as well.
> Agenda:
>  1) efficiency comparison data-mc (mc generic-mc cocktail)
>  2) fit stability and bias
>  3) background subtraction and study at low Mx
>  4) duplicate killing
>  5) comparison of neutrals in sp3-sp4
>  6) unblind?
>  7) BAD
>  8) organizational: review committe, coll wide talk, conferences, group status, ...
> Cheers,
> --U.