Hi Concezio, thanks so much for the answer and for pointing me to specific places in VVF! I am still in the process of going through the code and digesting what I see... However, it seems to me that the default behavior is to have all the CB parameters fixed in all fits (unless -fixsh is explicitely used) by looking at the code and my newest logfile. I assume I'll have more stuff on this eventually... Thanks, Kerstin > Hi Kerstin, > > I don't remember exactly the details, so perhaps Antonio and Roberto can > correct me if I am wrong... > > > > The parameters fixed in these fits come from mesparsetting.dat. > > Where do these numbers in mesparsetting.dat actually come from? > > I assume they come from some high statistics fits - could you > > give some details about these (what kind of data/MC, cuts applied, > > all params floated?,...)? > > > > They are obtained on the relevant samples (data, vub, vcb, other) after > applying the SL event selection. > Note also that in the VVF code we actually refit for the PDF parameters > after applying all cuts, and fix the fitted parameters in the subsequent > mes fits in bins of the kinematic variables involved (look at FitMes > method). > > > In the CM2 version of this file I see many comments of the sort > > "# not updated to CM2" - why is this? Did we actually have a look > > and see that the changes were negligible or has this simply not > > been looked at? > > > > I believe we planned to update them but at about the same time we > switched to Thorsten's model for the PDFs and consequently used > another .dat file (mesparsetting_thorsten.dat). > > > I see that we are fixing the width of the Crystal Ball function. > > Why is this fixed also in those fits which do have a quite > > large signal fraction? Has anyone ever tried to float this > > in say the high stat fits (like for the correctionratios) and/or > > the mES fits for the low mX bins? If not, why not? > > > > I think they were allowed to float when determining the PDF parameters > and fixed afterwards. Floating the mean and width of the CB function > should be simple, just run subVirFit.pl with the flag -fixshape (yes, I > know, it is reverse logic...). If you want to float the width only then > you need to modify VubMesUnb in VirUtil.icc at around here: > > if (fixpar == 0) { // preset parameters only > Rm->setVal(inputPar[VirClass::iMean]); > Rs->setVal(inputPar[VirClass::iSigma]); > ar->setVal(inputPar[VirClass::iArgus]); > } else if (fixpar == 1) { // set and fix all parameters (if > reasonable value is given) > if (inputPar[VirClass::iMean] > 0.) { Rm->setVal(inputPar > [VirClass::iMean]); Rm->setConstant(); } > if (inputPar[VirClass::iSigma] > 0.) { Rs->setVal(inputPar > [VirClass::iSigma]); Rs->setConstant(); } > if (inputPar[VirClass::iArgus] > -55.) { ar->setVal(inputPar > [VirClass::iArgus]); } > > Cheers, Concezio. > >