Hi Antonio,
For the record, now that we have the moments fixed for the three
different functional ansatze can you remake the plots of the kinematic
variables that you did previously?
Bob
On Fri, 6 Jul 2007, Antonio Petrella wrote:
> Hi all,
> I've recalculated the parameters for the three ansaetze.
> Here are their values:
>
> -- Exponential --
> a = 1.32669
> 0th moment = 1
> 1st moment = 0
> 2nd moment = 0.165477
>
> -- Gaussian --
> c = 0.3057134
> 0th moment = 1
> 1st moment = 0
> 2nd moment = 0.165495
>
> -- Roman --
> rho = 0.2667075
> 0th moment = 1
> 1st moment = 0
> 2nd moment = 0.165480
>
> New plots for the shape functions and their cumulative distributions are
> posted at:
> http://babar-hn.slac.stanford.edu:5090/hn/aux/petrella/SFplot_new.ps
> I would say that now we can trust efficiencies calculated using these
> parametrizations.
>
> ciao,
> Antonio
>
> Luth, Vera G. wrote:
> > Thank you Antonio,
> > This clearly explains the problem. As you change the ansatz for the SF,
> > the parameters have to be adjusted!
> >
> > Ciao
> > Vera
> >
> > -----Original Message-----
> > From: [log in to unmask]
> > [mailto:[log in to unmask]] On Behalf Of Antonio
> > Petrella
> > Sent: Thursday, July 05, 2007 6:56 AM
> > To: vub-recoil
> > Subject: Shape Function form
> >
> > Hi all,
> >
> > as Kerstin suggested in her message
> > http://babar-hn.slac.stanford.edu:5090/HyperNews/get/rev-SemiLep-06-04/1
> > 7/2.html,
> > I checked the first moments for each shape function ansatz (exponential,
> >
> > gaussian and roman) that I have implemented in my private version of
> > EvtGenModels in order to compute the correct phase space acceptance
> > needed for the calculation of tag efficiency when estimating the
> > uncertainties due to the different ansateze.
> >
> > The implementation of the SF formulae has been copied from the package
> > VubHybridModel.
> >
> > For each ansatz the same values for mb (4.6586) and a (1.32669)
> > parmeters are used, only the form is changed.
> >
> > We know that the 0th moment (A0) has to be equal to 1, the 1st moment
> > (A1) has to be equal to 0 and the 2nd moment (A2) has to be equal to
> > 1/3*mu_pi^2.
> >
> > Here's what I get:
> > -- Exponential form --
> > A0=1
> > A1=0
> > A2=0.165477
> >
> > Being A2 = (mB-mb)^2/(1+a), I could double check that is correctly
> > computed since I provide the masses and the a parmeter from the
> > decay.dec file: mB=5.2791, mb=4.6586 and a=1.32669, giving A2=0.165458.
> >
> > -- Gaussian form --
> > A0=1
> > A1=0
> > A2=0.089637
> >
> > -- Roman form --
> > A0=1
> > A1=0
> > A2=0.086776
> >
> > A2 is changing so mu_pi^2 is changing too.
> >
> > I have also made plots of the shape functions:
> > http://babar-hn.slac.stanford.edu:5090/hn/aux/petrella/SFplot.ps
> > one can easily see that they're pretty different.
> >
> > I'm a bit puzzled: should the a parameter be equal for all the forms? It
> >
> > seems, in this case, that there is no way to have mu_pi^2 unmodified.
> >
> > Do you have any comment on this?
> >
> > cheers,
> > Antonio
>
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/ Robert V. Kowalewski \/ Dept. of Physics and Astronomy \
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