Hi I'll have to leave a little before 9.
C.C.

On Mon, 23 Oct 2006, Kerstin Tackmann wrote:

>
> Hi all,
>
> here is an update on the D** modeling with what I learned from David
> Lange.
>
> What I take from David's email below  is (please feel free to disagree
> with my conclusions...):
>
> *Request new SP5 and SP6 (D** only) to replace the D** in the generic:
> This seems to work with a one-line-fix in the dec file for SP6, but not
> for SP5 (since SP5 is release 12 if I am not mistaken. I am checking
> with David to be sure.). I guess we would feel uncomfortable to use SP6-D**
> for all our D** for the real analysis as far as detector response and
> backgrounds are concerned.
>
> *Produce our own truth MC to produce weights:
> This should work fine if we can get EvtGen running in a release suitable
> for SP6. We could produce all we want:
> - SP8 by using David's switch
> - SP6 as default
> - SP5 by reverting the changes between SP5 and SP6 by hand
> (We need to change the dec file and evt.pdl for this.)
>
> I guess we should talk about this in the meeting tomorrow (I'll have to
> leave at 9:25 am.).
>
> Cheers,
> Kerstin
>
>
> Here is the actual email from David:
>
>
> Hi Kerstin,
>
> Sorry for the delay:
>
>> Thanks, David!
>>
>> Please allow me to ask another technical question: So if we try to
>> produce SP6-like D** (we are interested in the mass distribution
>> of B->D**lnu, so I am sure we are affected by changes in the lineshape)
>> and SP8-like D**, where do the two differ at the technical level,
>> what do we need to pay attention to? Can the change between the
>> two levels made at the dec-file level? (If so, starting with which
>> tag of EvtGen does that work?) Or do we need two different
>> version of the code (If so, which piece?)?
>
> The fix in the default MC is between r18 releases and r14 releases. The
> current sp6 release can be used to generate the buggy version and
> 'fixed' version by adding
>
> SP6LSFix <particle name>
>
> in the decay file.
>
> In sp8, it is not possible to go back to the sp6 buggy shape. There is a
> known residual problem in sp8 that may affect you described in
>
> https://www.slac.stanford.edu/babar-internal/BMO/BbrMeetingOrganizer/meetingDetails.html?mtgnum=437[1]
>
> Cheers-
>  David
>
>>
>> Thanks for your help,
>> Kerstin
>>
>> On Mon, 9 Oct 2006, David Lange wrote:
>>
>>> Hi Kerstin
>>>
>>> The problem discussed in this thread affects all particles. Depending on
>>> the mass/width/decay mode you are looking at, it may or may not be an
>>> issue. Until October 1, the easiest way was to request mc with a
>>> somewhat modified decay file. Now, the easiest thing is likely to get
>>> some sp8 and look at reweighting.
>>>
>>> david
>>>
>>>
>>> Kerstin Tackmann wrote:
>>>> *** Discussion title: Event Generators
>>>> Email replies to [log in to unmask] must include:
>>>>   In-Reply-To: <"/event_gen/498/2/4"@babar-hn.slac.stanford.edu>
>>>>   Subject: ...change this to be about your reply.
>>>>
>>>> Hi David,
>>>>
>>>> does this affect only the D_0^*0, or also the D_0^*+?
>>>> Does it affect the other D**?
>>>>
>>>> Our analysis uses SP5 and SP6 - what is our best option
>>>> to get the correct lineshape for the D**?
>>>> Reweighting probably can at most do part of what we
>>>> want because I remember the maximum allowed deviation from
>>>> mean mass is too big for some D** in SP5.
>>>>
>>>> Thanks,
>>>> Kerstin
>>>>
>>>>> Hi Liaoyuan
>>>>>
>>>>> I guess you mean 'between sp6 and sp8' below. As your plot illustrates
>>>>> nicely, some factors were missing in sp5/sp6 lineshapes, in this case,
>>>>> most importantly phase space factors. If you add the appropriate phase
>>>>> space factors to your BW curve, you should get the sp8 curve.
>>>>>
>>>>> david
>>>>>
>>
>
> -----------------------------------------------------------------------
> [1] https://www.slac.stanford.edu/babar-internal/BMO/BbrMeetingOrganizer/meetingDetails.html?mtgnum=437
>