* Sheila, anything you want to show concerning the new
notebook (version 1.1)?
The latest news on the workbook is summarized on the webpage:
http://www.slac.stanford.edu/~penguin/VubStuff/EvtVubBLNP4/index.html
I have not yet updated the workbook to Version 1.1.
However, I did look through the new notebook, and
then I sent the following email
to Mr. Neubert and Mr. Paz. Mr. Paz emailed me back
and said he would send a detailed reply next week.
So until then, I'm working on other stuff.
sheila
---------- Forwarded message ----------
Date: Thu, 3 Nov 2005 05:12:51 -0500 (EST)
From: Sheila Mclachlin <[log in to unmask]>
To: [log in to unmask]
Cc: [log in to unmask]
Subject: help with update to version 1.1 of B->Xulnu notebook
Hello,
I'm a grad student at BABAR, and I am trying
to write an event generator for inclusive B->Xulnu,
based on your notebook.
I had just gotten a generator based on
Version 1.0 to work, and then I learned
that there is a new Version 1.1 now.
For the generator, the only part I need
is rate3 for B->Xulnu.
I looked through the new notebook to try
to determine how your changes would
affect my generator. Here is a summary
of what I think. Could you please
let me know if it is correct?
The form of the shape functions is the
same. But now, instead of using Lambda and b
as input parameters, you are effectively
using mbSF and mupisqSF as input parameters,
and getting Lambda and b from them. Since
mbSF and mupisqSF are not used anywhere
else anyway, they are really just "Lambda
and b by another name." So my model,
which uses Lambda and b as input parameters,
and doesn't use mbSF and mupisqSF at all,
is still OK. However, if I wanted to,
I could make mbSF and mupisqSF the input
parameters, instead.
The main effect of the change is that when
Lambda and b are the input parameters,
then mbSF and mupisqSF are different
for different models (eg, exp vs gauss).
Whereas when mbSF and mupisqSF are the input
parameters, Lambda and b are different
for different models. I suppose this
might become important when users are
trying different models to see how the
variation affects their results.
I assume that for this purpose the
Version 1.1 method -- using mbSF and mupisqSF
as input parameters -- is better.
The other big change in Version 1.1 is the
change in the subleading shape functions.
In Version 1.0, you had two options
for wS: wS = w*S and wS = DS.
Now, since it is much harder to
do derivatives in C++ than in Mathematica,
for my old EvtGenModel I just used
the wS = w*S option, and filed the
other option away as a possible future
addition. But now I see you have only
the wS = DS option in Version 1.1.
This means that either I have to
write a differentiation program
(to make it easier to adapt the model
to incorporate many different shape
functions in the future) or differentiate
each function myself, separately (which
is easy enough for exp and gauss at least,
but will make it harder to add other models
in the future). Either way, it's kind of
a drag. So I am wondering: are the
subleading shape functions in Version 1.0
still OK? Can I use them instead?
Because using wS instead of DS will
certainly speed up the program. (It
is very slow already due to all the
4 unavoidable integrals.)
Also, a note to Mr. Paz, about the
maximum-rate thing: I ran some tests and
found that settting ratemax to 3.0
(units of GF^2 Vub^2/(pi^3 hbar) )
works pretty well. So you don't need to
send me the maximum rate after all.
Thanks for your help,
sheila
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