[Clas_lmd] lepton pion PID

Fri Jul 10 13:56:25 EDT 2015

Greetings,

"
Although it is not clear to me what are we going to learn from the 
requested plot I created it from g11 data.
See it here:
"
As you can see from your plots, middle and bottom, that there exists eta 
regardless of mass assignment. This means just assigning lepton mass 
does not necessarily mean they are leptons.

"
It would have been more interesting to compare the same plots from g12 
to understand which dataset is
more powerful statistically in particular channels.
"

See my last email.

BR
MK
----------------------------------------
Michael C. Kunkel, PhD
Forschungszentrum Jülich
Nuclear Physics Institute and Juelich Center for Hadron Physics
Experimental Hadron Structure (IKP-1)
www.fz-juelich.de/ikp

On 7/10/15 1:51 PM, Amaryan, Moskov wrote:
> Dear all,
>
> Although it is not clear to me what are we going to learn from the 
> requested plot I created it from g11 data.
> See it here:
>
> http://www.lions.odu.edu/~mamaryan/all_mxp.pdf 
> <http://www.lions.odu.edu/%7Emamaryan/all_mxp.pdf>
> The upper panel is invariant mass of e+e-\gamma squared, the middle 
> one is for M_{x}(p)^2 with electron assignment,
> the lower one is the same with pion mass assignment.
>
> It would have been more interesting to compare the same plots from g12 
> to understand which dataset is
> more powerful statistically in particular channels.
>
> Best regards,
> Moskov.
>
>> ________________________________________
>> From: Clas_lmd [clas_lmd-bounces at jlab.org 
>> <mailto:clas_lmd-bounces at jlab.org>] on behalf of Michael C. Kunkel 
>> [mkunkel at jlab.org <mailto:mkunkel at jlab.org>]
>> Sent: Thursday, July 09, 2015 7:02 AM
>> To: clas_lmd at jlab.org <mailto:clas_lmd at jlab.org>
>> Subject: Re: [Clas_lmd] lepton pion PID
>>
>> Greetings,
>>
>> Can you overlay the MxP^2 with pion mass setting on this plot? Using 
>> the same kinematic cuts except with pion pid?
>>
>>
>>
>> BR
>> MK
>> ----------------------------------------
>> Michael C. Kunkel, PhD
>> Forschungszentrum Jülich
>> Nuclear Physics Institute and Juelich Center for Hadron Physics
>> Experimental Hadron Structure (IKP-1)
>> www.fz-juelich.de/ikp 
>> <http://www.fz-juelich.de/ikp><http://www.fz-juelich.de/ikp>
>>
>> On 7/9/15 1:11 AM, Amaryan, Moskov wrote:
>> Dear all,
>>
>> I attach a plot with Mx(p)^2 and M(e+e-\gamma)^2 distributions 
>> overlaid. Statistics of both histograms are the same,
>> however, as one can see there is no peak of eta in the invariant mass 
>> squared, data are from g11.
>> Invariant mass has no eta in it similar  to what Michael showed for g12.
>> One can think of two possibilities, either these are true eta’s 
>> decaying to e+e-\gamma, or these are  remnants of eta->pi+pi-gamma 
>> events.
>> The latter hypothesis was ruled out by plotting invariant mass of 
>> pi+pi-\gamma or missing mass of proton for pion mass assignment
>> for the same events that make Mx(p)^2 under lepton assignment.
>>
>> Best regards,
>> Moskov.
>>
>> On Jul 8, 2015, at 11:02 PM, Amaryan, Moskov <MAmaryan at odu.edu 
>> <mailto:MAmaryan at odu.edu><mailto:MAmaryan at odu.edu>> wrote:
>>
>> Hi Michael,
>>
>> Thanks for your message, looks interesting.
>>
>> However we have shown in the CAA and also Georgie has shown it in our 
>> meetings that invariant mass of pi+pi-\gamma
>> resolution is much worse than missing mass of  proton.  The reason is 
>> energy resolution of the final state photon and
>> vertex resolution as momentum of the photon is defined through both 
>> of these, energy and vertex.
>> Therefore we use missing mass of  proton with other cuts, which use 
>> pion mass assignment to \pi^+ and \pi^-.
>>
>> Now what I have shown on Tuesday, was missing mass of proton with 
>> electron (positron) mass assignments.
>> There we clearly see a peak of eta. The mass assignment is arbitrary, 
>> of course, but requirement of missing mass squared
>> of pe+e- to be around zero (<0.01 GeV) and missing energy of pe+e- to 
>> be E_x>0.2 GeV makes this selection definite, not arbitrary.
>> And the fact that we see peak of eta is a proof that some of pi+pi- 
>> tracks are actually e+e- pairs
>>
>> The plot you sent around doesn’t show a peak of eta very clearly in 
>> the best topology with EC/CC, but one can imagine that with more 
>> statistics
>> the  eta peak will be visible. However without EC/CC there is no 
>> signature of eta whatsoever. Would it be visible in the missing mass 
>> of proton in g12?
>>
>> It wouldn’t make sense for me to argue that PID on leptons improves 
>> invariant mass e+e-\gamma, of course it does.
>>
>> The question was which fraction of events that make eta in the 
>> missing mass of proton with e+e-\gamma assignment is due to events 
>> that were
>> from pi+pi-\gamma final state.
>> I think we have shown that this fraction is negligible.
>>
>> It will be interesting to compare missing mass of the proton squared 
>> from g11 and g12 (for pe+e-gamma final state)  to see if because of 
>> different
>> acceptances these two data sets have similar or very different 
>> numbers of eta’s.
>>
>> It appeared that ntuples we are using from g11 have been eloss 
>> applied. In this case eloss for pions and leptons will be the same, I 
>> am not sure how different they should be, but the fact that we see 
>> peaks of pi0 and eta in the missing mass of proton is indicative that 
>> in the first approximation we can neglect eloss uncertainties.
>>
>> Best regards,
>> Moskov.
>>
>> On Jul 8, 2015, at 1:33 PM, Michael C. Kunkel <mkunkel at jlab.org 
>> <mailto:mkunkel at jlab.org><mailto:mkunkel at jlab.org>> wrote:
>>
>> Greetings,
>>
>> So I was curious to reproduce my study on pion contamination without 
>> the use of CC or EC quantities.
>> I am attaching a plot that shows G12 data that shows 3 lines.
>> Red: G12 data with eloss on pions, pion mass setting, invariant mass 
>> PipPimGam; conditions Ngamma > 0 && abs(mm2_PPipPimGam)<0.01 && 
>> mE_PPipPim > 0.2
>>
>> Blue: G12 data with eloss on leptons,lepton mass setting , invariant 
>> mass EpEmGam; conditions Ngamma > 0 && abs(mm2_PEpEmGam)<0.01 && 
>> mE_PEpEm > 0.2
>>
>> Cyan: G12 data with eloss on leptons,lepton mass setting , invariant 
>> mass EpEmGam; conditions Ngamma > 0 && abs(mm2_PEpEmGam)<0.01 && 
>> mE_PEpEm > 0.2 && lepton PID through CC and EC. Histogram is scale by x10
>>
>>
>> As I concluded years ago, and is seen in the histogram, without CC or 
>> EC, the eta peak cannot be reproduced in the proper place.
>>
>> Total data used:1/463 of g12 data set.
>>
>> Hope this helps.
>>
>>
>> BR
>> MK
>> ----------------------------------------
>> Michael C. Kunkel, PhD
>> Forschungszentrum Jülich
>> Nuclear Physics Institute and Juelich Center for Hadron Physics
>> Experimental Hadron Structure (IKP-1)
>> www.fz-juelich.de/ikp 
>> <http://www.fz-juelich.de/ikp><http://www.fz-juelich.de/ikp>
>>
>>
>>
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>> <Lepton_Pion_mass_comparision.pdf>_______________________________________________
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>>
>> Prof. Moskov Amaryan
>> Department of Physics
>> Old Dominion University
>> 4600 Elkhorn Avenue
>> Norfolk, VA 23529
>>
>> phone:757-683-4614
>>
>>
>>
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>>
>> Prof. Moskov Amaryan
>> Department of Physics
>> Old Dominion University
>> 4600 Elkhorn Avenue
>> Norfolk, VA 23529
>>
>> phone:757-683-4614
>>
>>
>>
>>
>>
>>
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>
> Prof. Moskov Amaryan
> Department of Physics
> Old Dominion University
> 4600 Elkhorn Avenue
> Norfolk, VA 23529
>
> phone:757-683-4614
>
>
>
>
>
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