Vub measurement using recoil of fully reconstructed Bs


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Riccardo Faccini <[log in to unmask]>
25 Oct 2002 00:55:55 -0700 (PDT)Fri, 25 Oct 2002 00:55:55 -0700 (PDT)
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Hi Urs,
my approach has been to make sure that the Ks bug removed and the no ks
bug removed MC look the same as far as rate and spectra are concerned. I
was expecting to make a rescaling, but when I did the comparison, I found
out that a killing is enough.

The reaction of the neutral group has been that we should just throw away
that MC. Once we have the full sample of generic we will be able to do so,
so I would keep this fix that works (Fabio confirmed it in b->s gamma)
waiting for the generic to be fully processed.

On Thu, 24 Oct 2002, Urs Langenegger wrote:

> Hoi Ric,
> discussions with Denis and Alessio  have not solved my confusion about
> your killing function.
> I  peeked into  the  gam lists  and  generator blocks  of events  with
> K0s->pi0pi0 in the  old MC. The wrong bumps do  not have a truth-match
> by virtue of the bug (I seem  to remember this, and I have not found a
> single counter  example). So either  they are merged with  the correct
> bump or we will never kill the proper one with the current setup.
> If  the bad  photons are  merged  with the  correct one  (this can  be
> checked from the kinematics of  the decay modulo resolutions since the
> correct photons have  the link back to the mothers),  killing is -- on
> an event by  event basis -- not the right thing  to do.  Rescaling the
> energy would seem more appropriate.
> If they are not merged and the  bad photons are still in the event, we
> should  be able  to find  the best  match to  the K0S  decay  from the
> unmatched photons and throw out  the correct ones. This amounts to the
> same as what is done in  VubRemoveOrphans. I guess it would be good to
> understand why VubRemoveOrphans fails to remove them properly.
> Cheers,
> --U.