[Brahms-dev-l] track vertex issue

Hello,

I noticed yesterday that the BrFsTrack vertex was different from the
BrFfsTrack vertex. That is in fact weird since the front part of any
BrFsTrack is a BrFfsTrack. After making several i/o tests, I realized that
it was no i/o bug but simply the following : in my main module chain, I
had the BrFsGlobalTrackFitterModule. That is not bad in itself except that
it resets the BrFsTrack vertex by projecting the newly refitted track to
the "beam plane" sitting exactly at z = 0. When in AuAu, we use the
beam-beam counter vertex, that is not good. That might be good in other
cases but not in AuAu. So I will simply change the behavior of this
module. I think that in order to make the change smooth, I just have to
make the beam plane sitting at z = z(track vertex). Thus, if you had used
the beam beam vertex before this track refitting stuff, you should get the
expected track vertex. Of course, this will become then a redundant
operation but I don't want to break code that works for pp or dAu.

Djam


-- 
Djamel Ouerdane ------------------------------------------o
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