GSI Forum: Analysis » Small positive chi2 values in PndKinFitter

Home » PANDA » PandaRoot » Analysis » Small positive chi2 values in PndKinFitter

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

Small positive chi2 values in PndKinFitter [message #14682]

Tue, 30 April 2013 11:13

Lu Cao
Messages: 77
Registered: February 2013

continuous participant

From: *ikp.kfa-juelich.de

Dear all,

In the simulation (#18621) of pbar p -> Ds+ Ds-; Ds- -> K+ K- pi-; Ds+ ->eta e+ nue; eta -> pi+ pi- pi0, I did the mass constraint fitting to the pi0 candidates with PndKinFitter. All the chi2s are pretty small with the mean value of ~0.001. This also happens in the case of eta.

I noticed the previous topic discussed by Albrecht about the negative and extremely small chi2 in PndKinVtxFitter.
https://forum.gsi.de/index.php?t=tree&th=3385&start=0&rid=19 79&S=7cee6febef5676d17dc9e3154e1269e2

Considering the formula for chi2, the small values may be due to a large sigma in the denominator.
Does anybody have some solutions or hints to improve it?
or is there any way else to understand this problem?

Thanks in advance.

Report message to a moderator

[Message index]

		Small positive chi2 values in PndKinFitter By: Lu Cao on Tue, 30 April 2013 11:13
		Re: Small positive chi2 values in PndKinFitter By: StefanoSpataro on Tue, 30 April 2013 14:13
		Re: Small positive chi2 values in PndKinFitter By: Klaus Götzen on Tue, 30 April 2013 17:41
		Re: Small positive chi2 values in PndKinFitter By: StefanoSpataro on Tue, 30 April 2013 18:44
		Re: Small positive chi2 values in PndKinFitter By: Klaus Götzen on Tue, 30 April 2013 20:33
		Re: Small positive chi2 values in PndKinFitter By: Lu Cao on Mon, 27 May 2013 13:14

Previous Topic:	analysis of multiple files
Next Topic:	how to convert kinematic variables from lab frame to cm frame in root

Goto Forum:

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Sat Mar 14 05:52:15 CET 2026

Total time taken to generate the page: 0.00732 seconds