Home » PANDA » PandaRoot » Analysis » Vertex fitters' problems
Vertex fitters' problems [message #14847] |
Thu, 06 June 2013 12:40 |
StefanoSpataro
Messages: 2736 Registered: June 2005 Location: Torino
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first-grade participant |
From: *to.infn.it
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Dear all,
Laura and me are checking the features of our vertex fitters,
with the trunk version 20077. In the latest trunk the function GetMcTruth() returns null pointer, than the trunk cannot be used.
We have simulated 10k ppbar->D*+D*-->D0pi+D0barpi-->k-pi+pi+k+pi-pi-, we have used MC truth index to identify the kaon- and the pion+ of the D0 (we have not touched the d0bar).
We have uploaded all the relevant macros, you have only to modify the path of the DEC file in the sim macro.
We run PndKinVtxFitter, PndVtxPoca and PndVtxPRG and compared the results. We were able to find a tutorial only for PndKinVtxFitter. The tutorial for PndVtxPoca and PndVtxPRG is missing then we hope we are using them in the proper way.
Please check the code.
Vertex residuals reco - mc (in cm) and chi2 for PndKinVtxFitter:
Vertex residuals reco - mc (in cm) and chi2 for PndVtxPoca:
Vertex residuals reco - mc (in cm) and chi2 for PndVtxPRG:
These are the obtained resultion values:
|X res | Y res | Z res |
PndKinVtxFitter | 2um | 2um | wrong and asymmetric |
PndVtxPoca | 400um | 400um | 400um |
PndVtxPRG | 60um | 60um | 100um |
Then...
PndKinVtxFitter is obtaining very very very narrow distributions on X and Y. How is it possible? Z distribution is screwed. Chi2 is very low.
PndVtxPoca has too large resolution values, does not work. Decent chi2 maybe.
PndVtxPRG has more reasonable values, even if I believe they are a bit large. It is much slower than the others, most probably because of the 10 iterations, but w/o a tutorial we were not sure about which number to use. Chi2 too low.
Still not checked composite particles (i.e. D*)
Then...
What to use? Could you please take a look?
Many tanks in advance.
Laura and Stefano
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Re: Vertex fitters' problems [message #14892 is a reply to message #14888] |
Fri, 21 June 2013 18:43 |
L. Zotti
Messages: 6 Registered: December 2010
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occasional visitor |
From: *to.infn.it
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Dear Ralf,
thanks for your helping.
Looking in your analysis macro, I found you just missed one "break" at line 273. Actually with this modification, I got some better results from the ChiVtx fitter.
Moreover, cleaning the sample looking at the FitStatus flag, I got the following resolution:
PndChiVtxFitter x:32um y:52um z:138
PndVtxPRG (full) x:61um y:60um z:103um
PndVtxPRG (fast) x:60um y:61um z:103um
Plots for PndChiVtxFitter:
Plots for PndKinVtxFitter:
Plots for PndVtxPoca
Plots for PndVtxPRG
1)fast:
2)full:
Still to be understood why resolution are different in x and y for the PndChiVtxFitter.
Do you think this results are reliables?
The KinVtxFitter and the Poca one still give strange results.
For what concern the kinematics, actually the kaons and the pions from the d0-meson are well separated in angle, how you can see here:
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Attachment: opening_angle.png
(Size: 7.96KB, Downloaded 543 times)
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Attachment: ChiVtx.png
(Size: 25.80KB, Downloaded 542 times)
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Attachment: FastVtx.png
(Size: 27.66KB, Downloaded 539 times)
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Attachment: FullVtx.png
(Size: 26.98KB, Downloaded 526 times)
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Attachment: KinVtx.png
(Size: 26.92KB, Downloaded 515 times)
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Attachment: PocaVtx.png
(Size: 27.32KB, Downloaded 536 times)
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Re: Vertex fitters' problems [message #15023 is a reply to message #15019] |
Fri, 26 July 2013 13:26 |
StefanoSpataro
Messages: 2736 Registered: June 2005 Location: Torino
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first-grade participant |
From: 2.235.190*
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Very interesting...
root [0] TVector3 e(1,2,3)
root [1] TVector3 f=(1,2,3)
root [2] e.Print()
TVector3 A 3D physics vector (x,y,z)=(1.000000,2.000000,3.000000) (rho,theta,phi)=(3.741657,36.699225,63.434949)
root [3] f.Print()
TVector3 A 3D physics vector (x,y,z)=(3.000000,0.000000,0.000000) (rho,theta,phi)=(3.000000,90.000000,0.000000)
root [4] TVector3 d
root [5] d=(1,2,3)
(class TVector3)41869040
root [6] d.Print()
TVector3 A 3D physics vector (x,y,z)=(3.000000,0.000000,0.000000) (rho,theta,phi)=(3.000000,90.000000,0.000000)
and without a single complain...
[Updated on: Fri, 26 July 2013 14:42] Report message to a moderator
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