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Chi2 of kinematic and vertex fitters [message #15750]

Thu, 28 November 2013 17:07

StefanoSpataro
Messages: 2736
Registered: June 2005
Location: Torino

first-grade participant

From: *to.infn.it

Dear analysis experts,
I run the standard macro/run/ana_complete.C macro and checked the chi2 distributions of the three fitters implemented there, vertex mass and 4C.
Here the plots:

index.php?t=getfile&id=7668&private=0

You can see that the vertex fitters shows still negative values of chi2. I supposed this was fixed. Did I forget something, or maybe there is still something to debug?

Attachment: chi2.gif
(Size: 14.08KB, Downloaded 769 times)

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Re: Chi2 of kinematic and vertex fitters [message #15752 is a reply to message #15750]

Tue, 03 December 2013 11:49

Elisabetta Prencipe (2)
Messages: 214
Registered: February 2013

first-grade participant

From: *ext.kfa-juelich.de

Hi Stefano,

I am running my test jobs in the pandaroot rev. 22626, and I found again negative chi2 of the vertex fit (only; the mass fit constraint does not give negatice chi2 in my case). The difference with the previous revision (rev 21003) is that now I get improvements: only decays where photons got involved give me few entries with negative chi2. In the previous revision (21003), I had many of them. Also, the efficiency is definitively improved in the new revision (22626): in the decay p pbar to Ds Ds1'(2536)+, Ds1'(2536)+ to D*0pi+, I have got:

rev 21003: 21% efficiency
rev 22626: 30% efficiency

cheers, Elisabetta

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Re: Chi2 of kinematic and vertex fitters [message #15753 is a reply to message #15750]

Tue, 03 December 2013 14:23

Ralf Kliemt
Messages: 507
Registered: May 2007
Location: GSI, Darmstadt

first-grade participant

From: *gsi.de

Hi.

Please note that there are negative chisquare values for various failed fit conditions.

Ralf

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Re: Chi2 of kinematic and vertex fitters [message #15755 is a reply to message #15753]

Fri, 06 December 2013 17:39

StefanoSpataro
Messages: 2736
Registered: June 2005
Location: Torino

first-grade participant

From: *to.infn.it

Then the standard macro macro/run/ana_complete.C should be modified in order to do the proper selections.

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Re: Chi2 of kinematic and vertex fitters [message #15760 is a reply to message #15753]

Tue, 10 December 2013 18:16

StefanoSpataro
Messages: 2736
Registered: June 2005
Location: Torino

first-grade participant

From: 140.181.10*

I tried to do the following to avoid fit errors:

                        PndKinVtxFitter vtxfitter(jpsi[j]);     // instantiate a vertex fitter
                        if (!vtxfitter.Fit()) continue;

But I have still negative chi2. Maybe I missed something?

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Re: Chi2 of kinematic and vertex fitters [message #18346 is a reply to message #15750]

Mon, 06 July 2015 14:14

Jennifer Pütz
Messages: 47
Registered: April 2015
Location: FZ Juelich

continuous participant

From: *ikp.kfa-juelich.de

Hi everyone,

I still have negative Chi2 when I use the kinematic and the vertex fitters. Has anybody an idea how to fix it?

Cheers

Jenny

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Re: Chi2 of kinematic and vertex fitters [message #18348 is a reply to message #18346]

Mon, 06 July 2015 14:18

StefanoSpataro
Messages: 2736
Registered: June 2005
Location: Torino

first-grade participant

From: 91.253.38*

Is it better to provide a code snipplet. There are several fitters.

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Re: Chi2 of kinematic and vertex fitters [message #18351 is a reply to message #15750]

Mon, 06 July 2015 14:56

Jennifer Pütz
Messages: 47
Registered: April 2015
Location: FZ Juelich

continuous participant

From: *ikp.kfa-juelich.de

Ok, here is an example with negative Chi2 for the 4C-Fit (pbar p -> Lambda0 + AntiLambda0)
------

double pbarmom = 1.712;
double p_m0 = TDatabasePDG::Instance()->GetParticle("proton")->Mass();
TLorentzVector ini (0,0, pbarmom, sqrt(p_m0*p_m0+ pbarmom*pbarmom)+p_m0);

RhoCandList piplus, piminus, lambda0, antiLambda0, proton, antiProton, pbarpsystem, Lambda0Fit, AntiLambda0Fit;

TString PidSelection = "PidAlgoIdealCharged";

theAnalysis->FillList(piminus, "PionAllMinus", PidSelection);
theAnalysis->FillList(piplus, "PionAllPlus", PidSelection);
theAnalysis->FillList(proton, "ProtonAllPlus", PidSelection);
theAnalysis->FillList(antiProton, "ProtonAllMinus", PidSelection);

int evt=0;
while (theAnalysis->GetEvent() && ++evt<nevts){

//***Lambda0 -> PiMinus + Proton
lambda0.Combine(piminus,proton);
lambda0.Select(lambdaMassSelector);
lambda0.SetType(3122);

for (int j=0; j<lambda0.GetLength(); ++j){

PndKinVtxFitter vertexfitterLambda0 (lambda0[j]);
vertexfitterLambda0.Fit();
RhoCandidate * lambda0Fit = lambda0[j]->GetFit();
Lambda0Fit.Append(lambda0Fit);

}

//***AntiLambda0 -> PiMinus + Proton
antiLambda0.Combine(piplus,antiProton);
antiLambda0.Select(lambdaMassSelector);
antiLambda0.SetType(-3122);

for (int j=0; j<antiLambda0.GetLength(); ++j){
PndKinVtxFitter vertexfitterAntiLambda0 (antiLambda0[j]);
vertexfitterAntiLambda0.Fit();
RhoCandidate * antiLambda0Fit = antiLambda0[j]->GetFit();
AntiLambda0Fit.Append(antiLambda0Fit);
}

pbarpsystem.Combine(Lambda0Fit, AntiLambda0Fit);
pbarpsystem.SetType(88888);

for (int j=0; j<pbarpsystem.GetLength(); ++j){
PndKinFitter Fitter4c (pbarpsystem[j]);
Fitter4c.Add4MomConstraint(ini);
Fitter4c.Fit();
}

Lambda0Fit.Cleanup();
AntiLambda0Fit.Cleanup();
}
-------
index.php?t=getfile&id=8446&private=0

Attachment: 4C_negative_chi2.png
(Size: 21.90KB, Downloaded 525 times)

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Re: Chi2 of kinematic and vertex fitters [message #18362 is a reply to message #18351]

Wed, 08 July 2015 10:49

StefanoSpataro
Messages: 2736
Registered: June 2005
Location: Torino

first-grade participant

From: *ip71.fastwebnet.it

Can you post all the macros you used?

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Re: Chi2 of kinematic and vertex fitters [message #18363 is a reply to message #18362]

Wed, 08 July 2015 11:20

Jennifer Pütz
Messages: 47
Registered: April 2015
Location: FZ Juelich

continuous participant

From: *ikp.kfa-juelich.de

attached you find the macros

Attachment: sim_complete.C
(Size: 7.73KB, Downloaded 251 times)
Attachment: digi_complete.C
(Size: 4.62KB, Downloaded 238 times)
Attachment: recoideal_complete.C
(Size: 6.35KB, Downloaded 276 times)
Attachment: pidideal_complete.C
(Size: 3.78KB, Downloaded 243 times)
Attachment: analysis_pbarp_lambda0.C
(Size: 16.44KB, Downloaded 270 times)
Attachment: lambda0_antilambda0_piminus_p_piplus_antip.dec
(Size: 0.20KB, Downloaded 257 times)

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Re: Chi2 of kinematic and vertex fitters [message #18364 is a reply to message #18363]

Wed, 08 July 2015 11:26

StefanoSpataro
Messages: 2736
Registered: June 2005
Location: Torino

first-grade participant

From: *ip71.fastwebnet.it

PndMCIdealTrackFinderNewLinks is not meant for analysis but just for QA, at the moment.
Please use more standard reconstruction macros (-> macro/run/recoideal_complete.C).

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Re: Chi2 of kinematic and vertex fitters [message #18370 is a reply to message #18364]

Wed, 08 July 2015 15:28

Jennifer Pütz
Messages: 47
Registered: April 2015
Location: FZ Juelich

continuous participant

From: *ikp.kfa-juelich.de

After I tried it with the standard reconstruction macro and now there are no negative chi2 for the 4c fitter.

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Re: Chi2 of kinematic and vertex fitters [message #18371 is a reply to message #18370]

Thu, 09 July 2015 11:39

StefanoSpataro
Messages: 2736
Registered: June 2005
Location: Torino

first-grade participant

From: *to.infn.it

Then maybe there are problems of covariance matrix in the new ideal tracker, or most probably it is not properly linked to the pidcorrelator.

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