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Re: Problem with mass constraint fit for two gamma [message #16869 is a reply to message #16868]

Mon, 30 June 2014 16:51

Lu Cao
Messages: 77
Registered: February 2013

continuous participant

From: *ikp.kfa-juelich.de

Hi Donghee and all,

this situation is the same in reconstructing pi0->gamma gamma, as I reported before.

In the fast sim, the invariant mass spectrum of the combination of two photons has a "nice" distribution peaked at pi0 mass, so it's understandable that the mass constraint fit can work as expected. In the full sim, the invariant mass distribution is filled with a significant "background" which may course problems of convergence in mass constraint fit, e.g. too small chi2, prob squeezed to 1.

Since the PndKinFitter:AddMassConstraint() works fine for charged particles as well as the neutral in the fast sim, I'd like to guess the tool itself has no problem but to understand why the two-photon invariant mass distribution has so much "background" in the full sim. Is there any possible incorrect combinatorics, or where're the extra photons coming from?

Donghee, could you also show the gg invarit mass spectrum in your case?

Best regards,
Lu

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[Message index]

		[FIXED] Problem with mass constraint fit for two gamma By: donghee on Mon, 30 June 2014 10:56
		Re: Problem with mass constraint fit for two gamma By: Lu Cao on Mon, 30 June 2014 16:51
		Re: Problem with mass constraint fit for two gamma By: StefanoSpataro on Mon, 30 June 2014 17:51
		Re: Problem with mass constraint fit for two gamma By: donghee on Tue, 01 July 2014 10:12
		Re: Problem with mass constraint fit for two gamma By: StefanoSpataro on Tue, 01 July 2014 10:24
		Re: Problem with mass constraint fit for two gamma By: donghee on Tue, 01 July 2014 10:35
		Re: Problem with mass constraint fit for two gamma By: StefanoSpataro on Tue, 01 July 2014 10:37
		Re: Problem with mass constraint fit for two gamma By: Dima Melnychuk on Tue, 01 July 2014 11:06
		Re: Problem with mass constraint fit for two gamma By: donghee on Tue, 01 July 2014 14:17
		Re: Problem with mass constraint fit for two gamma By: Lu Cao on Thu, 17 July 2014 13:20
		Re: Problem with mass constraint fit for two gamma By: StefanoSpataro on Thu, 17 July 2014 13:34
		Re: Problem with mass constraint fit for two gamma By: donghee on Tue, 01 July 2014 10:57
		Re: Problem with mass constraint fit for two gamma By: StefanoSpataro on Tue, 01 July 2014 10:59
		Re: Problem with mass constraint fit for two gamma By: donghee on Tue, 01 July 2014 11:08
		Re: Problem with mass constraint fit for two gamma By: Dima Melnychuk on Tue, 01 July 2014 11:58
		Re: Problem with mass constraint fit for two gamma By: donghee on Wed, 02 July 2014 11:57
		Re: Problem with mass constraint fit for two gamma By: StefanoSpataro on Wed, 02 July 2014 12:01
		Re: Problem with mass constraint fit for two gamma By: donghee on Wed, 02 July 2014 12:28
		Re: Problem with mass constraint fit for two gamma By: StefanoSpataro on Wed, 02 July 2014 13:24
		Re: Problem with mass constraint fit for two gamma By: Dima Melnychuk on Wed, 02 July 2014 12:26
		Re: Problem with mass constraint fit for two gamma By: donghee on Thu, 03 July 2014 00:29
		Re: Problem with mass constraint fit for two gamma By: Dima Melnychuk on Thu, 03 July 2014 13:29
		Re: Problem with mass constraint fit for two gamma By: donghee on Thu, 03 July 2014 23:57
		Re: Problem with mass constraint fit for two gamma By: Dima Melnychuk on Fri, 04 July 2014 11:23
		Re: Problem with mass constraint fit for two gamma By: StefanoSpataro on Sun, 06 July 2014 06:09
		Re: Problem with mass constraint fit for two gamma By: donghee on Mon, 07 July 2014 11:04
		Re: Problem with mass constraint fit for two gamma By: Dima Melnychuk on Mon, 07 July 2014 11:13
		Re: Problem with mass constraint fit for two gamma By: donghee on Mon, 07 July 2014 13:54
		Re: Problem with mass constraint fit for two gamma By: StefanoSpataro on Mon, 07 July 2014 14:03
		Re: Problem with mass constraint fit for two gamma By: StefanoSpataro on Wed, 16 July 2014 17:49
		Re: Problem with mass constraint fit for two gamma By: donghee on Wed, 16 July 2014 20:28
		Re: Problem with mass constraint fit for two gamma By: StefanoSpataro on Wed, 16 July 2014 22:56
		Re: Problem with mass constraint fit for two gamma By: donghee on Thu, 17 July 2014 10:29
		Re: Problem with mass constraint fit for two gamma By: StefanoSpataro on Thu, 17 July 2014 10:34
		Re: Problem with mass constraint fit for two gamma By: donghee on Thu, 17 July 2014 10:59

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