GSI Forum
GSI Helmholtzzentrum für Schwerionenforschung

Home » PANDA » PandaRoot » Analysis » Invariant Mass Distribution Widening after 4C Fit
Invariant Mass Distribution Widening after 4C Fit [message #18356] Wed, 08 July 2015 09:37 Go to previous message
André Zambanini is currently offline  André Zambanini
Messages: 17
Registered: February 2012
Location: FZ Jülich
occasional visitor
From: *ext.kfa-juelich.de
Hi everyone,

during my investigation of cascade reconstruction with PandaRoot, I found that after the four-constraint fitter my mass resolution got worse. You can see the difference in the plot I attached. Shown are the invariant mass distributions after applying a cut on the probability (>0.01) of the four-constraint fit, once with the pre-fit values (blue) and once with the values after the fit (green).

My decay is p̅p → Ξ̅Ξ → Λ̅π⁺ & ΛK⁻ with Λ → π⁻p and Λ̅ → π⁺p̅. So in my reconstruction I'm dealing with neutral particles (Λ). I asked a bit around here in the institute and it seems, others see a similar effect when having a mixture of neutral and charged candidates as input to the 4C fitter.

I'm running with trunk r27694 but it has been seen from others here with scrut14 as well. More details like a minimal running example will follow as soon as I have concluded my thesis, which is due in the next days. In the meantime: did anyone else see something like this? If so, is there an explanation to that?

Best,
-André

PS: The mass values are taken from the PndRhoTupleQA method qaCand().

index.php?t=getfile&id=8454&private=0
  • Attachment: dm_xi.png
    (Size: 94.07KB, Downloaded 592 times)

[Updated on: Wed, 08 July 2015 09:40]

Report message to a moderator

 
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Read Message
Previous Topic: Chi2 of kinematic and vertex fitters
Next Topic: entries at unphysical mass after vertex fit
Goto Forum:
  


Current Time: Tue Mar 19 10:55:51 CET 2024

Total time taken to generate the page: 0.00977 seconds