GSI Forum - RDF feed
https://forum.gsi.de/index.php
some options for eta_c analysis
https://forum.gsi.de/index.phpindex.php?t=rview&goto=12709&th=3374#msg_12709
I have tried several options in eta_c reconstruction as its was suggested by Stefano and here are the results.
I used for analysis data on grid run 925oldnocu (release july11).
1. Instead of selecting best eta_c candidate after vertex fit (using its chi2) I tried a preselection of best candidate using chi2 defined as (totalreco_mass-etac_mass)^2/sigma(eta_c)^2+(phi1reco_mass-phimass)^2/si gma(phi)+(phi2reco_mass-phimass)^2/sigma(phi).
And here there is a small improvement in efficiency and eta_c resolution and no improvement in phi mass resolution (efficiency 24.0%, sigma(eta_c)=32.8 MeV, sigma(phi)= 3.92 MeV).
For comparison with selection of best candidate after vertex fit (efficiency 22.8%, sigma(eta_c)=33.2 MeV, sigma(phi)= 3.92 MeV)
.
2. I also tried to perform a mass fitter for phi mass and here is the eta_c mass resolution after combining 2 phi after this fitter (PndKinFitter).
Here the best candidate is selected by difference between reconstructed and nominal eta_c mass and resolution is 34.7 MeV, i.e worse than with vertex fit. So I would exclude this option in eta_c analysis.
Dima]]>Dima Melnychuk2011-10-11T12:55:01-00:00Re: some options for eta_c analysis
https://forum.gsi.de/index.phpindex.php?t=rview&goto=12710&th=3374#msg_12710
thanks for the checks.
If I compare the maximum of etac peaks with the last plot, it seems to me that with the mass fitter you have higher statistics (or maybe higher bg). Quite strange...
]]>StefanoSpataro2011-10-11T13:28:28-00:00