Dear Stefano,

What you are looking at is a simplistic Mass constraint fit which fixes everything with respect to the constrained mass.
I had a look at the PndKinFitter class.

The delta mass peak can be obtained by replacing ( line : 339 -348 Trunk version ( rev: 21681) by the following code snippet


fmD[fNc+0][kN+0] = -2.*Px;
fmD[fNc+0][kN+1] = -2.*Py;;
fmD[fNc+0][kN+2] = -2.*Pz;
fmD[fNc+0][kN+3] = 2.*Etot;
fmD[fNc+0][kN+4] = 2.*a*Py;
fmD[fNc+0][kN+5] = -2.*a*Px;
fmD[fNc+0][kN+6] = 0.0;

I have tested it with the macro in /macro/run/ana_complete.C Unfortunately my wiki and forum login access is no longer there ( as it was with my FZ email) .

Actually the full mass constraint fit should include the vertex information and this can be implemented with not much effort.
I will see if I can do that. In that case, what Ralf pointed out in the forum is right.

Please tell me if it is fine.

cheers,
Vishwajeet