Hi all,

 since I would like to calculate precisely the ratio
eps_t^u/eps_t^sl I used the cocktail and the generic MC
with different levels of purities.

 This ratio can be calculated easily doing

 eps_t^u/eps_t^sl = N(Vub) / N(Vcb+Vub) * ratioBR_generated^-1

 Assuming :

 ratioBR_B0(SP3) = 0.00888
 ratioBR_B+(SP3) = 0.00978

 ratioBR_B0(SP4) = 0.01287
 ratioBR_B+(SP4) = 0.01281

 (this is from the DECAY.DEC)

 I got

 Cocktail
 --------

 (eps_t^u/eps_t^sl)_B0_SP3 = 0.92 +- 0.06

 (eps_t^u/eps_t^sl)_B+_SP3 = 0.87 +- 0.05

 (eps_t^u/eps_t^sl)_B0_SP4_run1 = 0.91 +- 0.08

 (eps_t^u/eps_t^sl)_B+_SP4_run1 = 0.88 +- 0.07

 (eps_t^u/eps_t^sl)_B0_SP4_run2 = 1.00 +- 0.09

 (eps_t^u/eps_t^sl)_B+_SP4_run2 = 0.90 +- 0.09


 As you see most of the results are below 1. The problem
here is that I am not perfectly sure of the generated ratioBR
since BR(b->ulnu) changed a lot in the releases 8.6, 8.8. ,10.-
and part of the MC was produced with different releases even on SP3 or
SP4.

 The fact that this ratio is not different from 1 (I can't understand
why breco should be less efficient for b->ulnu events...) seems to
be confirmed by the generic MC SP4 on run2


 (eps_t^u/eps_t^sl)_B0_SP4_run2 = 1.00 +- 0.10

 (eps_t^u/eps_t^sl)_B+_SP4_run2 = 0.96 +- 0.09

 since this is probably the most coherent MC (generated with the same
DECAY.DEC)


 Probably we need a different approach to calculate the value of this
ratio on large statistics. MC truth from root files can't be used since
it is biased by the Semiexcl selection.


 Any suggetion?


 Daniele