[Clas_lmd] lepton pion PID

[Michael C. Kunkel]

Greetings,

I have reproduced my pion/lepton analysis partly. However I think the 
plots I show in the attachment can aide in the understanding of why 
further constraints, such as Cherenkov or Electromagnetic Calorimeter, 
is needed.

page 1)
Black: Mx(p) with Mx(pe+e-) cuts
Purple : Mx(p) with Mx(ppi+pi-) cuts
conclusion: for eta there is a slight rejection, but nothing that 
concretely give favor to leptons over pions, or vise-versa.

page 2)
Black: M(e+e-gamma) with Mx(pe+e-) cuts
Purple : M(pi+pi-gamma) with Mx(ppi+pi-) cuts
conclusion: Hadronic contribution of pions appears dominant, makes sense 
since the cross-section of this is greater

page 3)
Gold: Mx(p) with Mx(pe+e-) cuts also EC/CC requirements defined by g12
Cyan : M(e+e-gamma) with Mx(pe+e-)cuts also EC/CC requirements defined 
by g12
conclusion: Without bremsstrahlung correct, the missing mass has better 
resolution, however the EC/CC cuts show peak definition

So, I hope it can be seen why I am over speculative about the analysis 
involving leptons PID through mass setting only.

Again, I 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

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>> wrote:
>
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