Print

---

Hi all,

 using the last version of recoilNtp and abcFit I started to look at the
effect of the kinematic fit on the Vub-Vcb separation.
 In:

 http://www.slac.stanford.edu/~daniele/vub/mx.gif  with kin fit

 http://www.slac.stanford.edu/~daniele/vub/mxfit.gif  without kin fit

 you see the "classic" plot for each component after all cuts
with and without the kin fit (B0 Cocktail MC). The D/D* peak has more
events and the Vcb tail at low Mx seems to be less evident after the fit
but the difference is not dramatic.

 This observation is confirmed by the fit result for the BR(btoulnu)
(error basically unchanged) and by the plot:

 http://www.slac.stanford.edu/~daniele/vub/mxfitvsmx.gif

 that shows Mxhadfit vs Mxhad after all analysis cuts. Below 1.5 GeV
Mxhadfit is almost identical to mxhad and this implies that the separation
Vub-Vcb remains the same.

 Further MC studies are needed to understand the leakage at low Mx for
Vcb (Guglielmo is studing MC truth for Vcb in Mx<1.5GeV).

 Daniele