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Vertex fitter for eta_c analysis [message #12251] Wed, 13 July 2011 16:31 Go to previous message
Dima Melnychuk is currently offline  Dima Melnychuk
Messages: 213
Registered: April 2004
Location: National Centre for Nucle...
first-grade participant
From: *fuw.edu.pl
Dear colleagues,

I would like to inform you that Elisa has found a bug in my eta_c analysis macro related to usage of vertex fitter and after correction it gives reasonable results in the sense of mass distribution.

Using PndKinVtxFitter eta_c and phi mass looks like
index.php?t=getfile&id=6499&private=0

And for comparison using 4C kinematics fit

index.php?t=getfile&id=6500&private=0

So in both cases mass resolution loos almost identical.

In case of 4C-fit daughter particles are not updated after the fit, i.e. it shouldn't modify the shape of mass distribution, but for vertex fit daughter particles are updated and I would expect bigger improvement/difference of at least eta_c mass, but it's not the case.

And I didn't look yet how position of the vertex is reconstructed, i.e. (reconstructed - MonteCarlo).

But in principle now both fitters could be used in analysis.

Dima
 
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