GSI Forum: Tracking » some options for eta

Home » PANDA » PandaRoot » Tracking » some options for eta_c analysis

Show: Today's Messages :: Polls :: Message Navigator

some options for eta_c analysis [message #12709]

Tue, 11 October 2011 14:55

Dima Melnychuk
Messages: 213
Registered: April 2004
Location: National Centre for Nucle...

first-grade participant

From: *fuw.edu.pl

Hi,

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).
index.php?t=getfile&id=6667&private=0

For comparison with selection of best candidate after vertex fit (efficiency 22.8%, sigma(eta_c)=33.2 MeV, sigma(phi)= 3.92 MeV)

index.php?t=getfile&id=6668&private=0

.

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).

index.php?t=getfile&id=6669&private=0

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

Attachment: m_vertex_fit_preselection.png
(Size: 15.09KB, Downloaded 927 times)
Attachment: m_vertex_fit.png
(Size: 15.00KB, Downloaded 931 times)
Attachment: m_mass_fit.png
(Size: 12.11KB, Downloaded 873 times)

Report message to a moderator

Re: some options for eta_c analysis [message #12710 is a reply to message #12709]

Tue, 11 October 2011 15:28

StefanoSpataro
Messages: 2736
Registered: June 2005
Location: Torino

first-grade participant

From: 193.205.228*

Hi Dima,
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...

Report message to a moderator

Previous Topic:	Psi 3770 "best candidate" selection
Next Topic:	eta_c reconstruction efficiency

Goto Forum:

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Wed Nov 19 14:20:39 CET 2025

Total time taken to generate the page: 0.00723 seconds