 |
 |
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 >