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Greetings,<br>
<br>
"<br>
<div><font color="#ff0000">and plot missing mass of proton Mx(p)^2
under the same cuts as above with e+e- replaced by pi+pi- </font></div>
<font color="#ff0000">
</font>
<div><font color="#ff0000">and see a peak of eta then this would
have been an ambiguity </font></div>
<font color="#ff0000">
</font>
<div><font color="#ff0000">and would have prevented to identify
Dalitz decay.</font></div>
<br>
"<br>
<br>
This is exactly what you show in <br>
<a class="moz-txt-link-freetext" href="http://www.lions.odu.edu/~mamaryan/all_mxp.pdf">http://www.lions.odu.edu/~mamaryan/all_mxp.pdf</a><br>
You see an eta peak in both, meaning there is ambiguity.<br>
<br>
<pre class="moz-signature" cols="72">BR
MK
----------------------------------------
Michael C. Kunkel, PhD
Forschungszentrum Jülich
Nuclear Physics Institute and Juelich Center for Hadron Physics
Experimental Hadron Structure (IKP-1)
<a class="moz-txt-link-abbreviated" href="http://www.fz-juelich.de/ikp">www.fz-juelich.de/ikp</a></pre>
<div class="moz-cite-prefix">On 7/10/15 2:55 PM, Amaryan, Moskov
wrote:<br>
</div>
<blockquote cite="mid:BEFDD4EA-E38B-4847-AAF1-62D6CD0924EA@odu.edu"
type="cite">
<meta http-equiv="Content-Type" content="text/html;
charset=windows-1252">
Hi Michael,
<div><br>
</div>
<div>From the same experiment two decay modes have perfect right
to exist, namely eta->pi+pi-\gamma and eta->e+e-\gamma.</div>
<div><br>
</div>
<div>However if we select events which pass the following cuts:</div>
<div><br>
</div>
<div>1. missing mass squared abs(Mx(e+e-\gamma))^2 <0.01</div>
<div>2. missing energy squared Ex = E_beam + Mp - E(e+) -E(e-)
>0.2</div>
<div><br>
</div>
<div>and plot missing mass of proton Mx(p)^2 under the same cuts
as above with e+e- replaced by pi+pi- </div>
<div>and see a peak of eta then this would have been an ambiguity </div>
<div>and would have prevented to identify Dalitz decay.</div>
<div><br>
</div>
<div>But, this was not the case, as I showed in LMD meeting. </div>
<div><br>
</div>
<div>Best regards,</div>
<div>Moskov.</div>
<div><br>
</div>
<div><br>
<div>
<div>On Jul 10, 2015, at 9:56 PM, Michael C. Kunkel <<a
moz-do-not-send="true" href="mailto:mkunkel@jlab.org">mkunkel@jlab.org</a>>
wrote:</div>
<br class="Apple-interchange-newline">
<blockquote type="cite">
<div bgcolor="#FFFFFF" text="#000000">Greetings,<br>
<br>
<br>
<font color="#ff0000">"</font>
<div><font color="#ff0000">Although it is not clear to me
what are we going to learn from the requested plot I
created it from g11 data.</font></div>
<div><font color="#ff0000">See it here:</font></div>
<font color="#ff0000">"</font><br>
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.<br>
<br>
</div>
</blockquote>
<div><br>
</div>
<div><br>
</div>
<br>
<blockquote type="cite">
<div bgcolor="#FFFFFF" text="#000000"><font color="#ff0000">"<br>
</font>
<div><font color="#ff0000">It would have been more
interesting to compare the same plots from g12 to
understand which dataset is</font></div>
<div><font color="#ff0000">more powerful statistically in
particular channels.</font></div>
<font color="#ff0000">"<br>
</font><br>
See my last email.<br>
<pre class="moz-signature" cols="72">BR
MK
----------------------------------------
Michael C. Kunkel, PhD
Forschungszentrum Jülich
Nuclear Physics Institute and Juelich Center for Hadron Physics
Experimental Hadron Structure (IKP-1)
<a moz-do-not-send="true" class="moz-txt-link-abbreviated" href="http://www.fz-juelich.de/ikp">www.fz-juelich.de/ikp</a></pre>
<div class="moz-cite-prefix">On 7/10/15 1:51 PM, Amaryan,
Moskov wrote:<br>
</div>
<blockquote
cite="mid:9E9AF50B-943C-4D01-9506-F8EC068326B8@odu.edu"
type="cite">
<div>Dear all,</div>
<div><br>
</div>
<div>Although it is not clear to me what are we going to
learn from the requested plot I created it from g11
data.</div>
<div>See it here:</div>
<div><br>
</div>
<div><a moz-do-not-send="true"
href="http://www.lions.odu.edu/%7Emamaryan/all_mxp.pdf">http://www.lions.odu.edu/~mamaryan/all_mxp.pdf</a></div>
<div>The upper panel is invariant mass of e+e-\gamma
squared, the middle one is for M_{x}(p)^2 with
electron assignment,</div>
<div>the lower one is the same with pion mass
assignment.</div>
<div><br>
</div>
<div>It would have been more interesting to compare the
same plots from g12 to understand which dataset is</div>
<div>more powerful statistically in particular channels.</div>
<div><br>
</div>
<div>Best regards,</div>
<div>Moskov.</div>
<div><br>
<blockquote type="cite">________________________________________<br>
From: Clas_lmd [<a moz-do-not-send="true"
href="mailto:clas_lmd-bounces@jlab.org">clas_lmd-bounces@jlab.org</a>]
on behalf of Michael C. Kunkel [<a
moz-do-not-send="true"
href="mailto:mkunkel@jlab.org">mkunkel@jlab.org</a>]<br>
Sent: Thursday, July 09, 2015 7:02 AM<br>
To: <a moz-do-not-send="true"
href="mailto:clas_lmd@jlab.org">clas_lmd@jlab.org</a><br>
Subject: Re: [Clas_lmd] lepton pion PID<br>
<br>
Greetings,<br>
<br>
Can you overlay the MxP^2 with pion mass setting on
this plot? Using the same kinematic cuts except with
pion pid?<br>
<br>
<br>
<br>
BR<br>
MK<br>
----------------------------------------<br>
Michael C. Kunkel, PhD<br>
Forschungszentrum Jülich<br>
Nuclear Physics Institute and Juelich Center for
Hadron Physics<br>
Experimental Hadron Structure (IKP-1)<br>
<a moz-do-not-send="true"
href="http://www.fz-juelich.de/ikp">www.fz-juelich.de/ikp</a><<a
moz-do-not-send="true"
href="http://www.fz-juelich.de/ikp">http://www.fz-juelich.de/ikp</a>><br>
<br>
On 7/9/15 1:11 AM, Amaryan, Moskov wrote:<br>
Dear all,<br>
<br>
I attach a plot with Mx(p)^2 and M(e+e-\gamma)^2
distributions overlaid. Statistics of both
histograms are the same,<br>
however, as one can see there is no peak of eta in
the invariant mass squared, data are from g11.<br>
Invariant mass has no eta in it similar to what
Michael showed for g12.<br>
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.<br>
The latter hypothesis was ruled out by plotting
invariant mass of pi+pi-\gamma or missing mass of
proton for pion mass assignment<br>
for the same events that make Mx(p)^2 under lepton
assignment.<br>
<br>
Best regards,<br>
Moskov.<br>
<br>
On Jul 8, 2015, at 11:02 PM, Amaryan, Moskov <<a
moz-do-not-send="true"
href="mailto:MAmaryan@odu.edu">MAmaryan@odu.edu</a><<a
moz-do-not-send="true"
href="mailto:MAmaryan@odu.edu">mailto:MAmaryan@odu.edu</a>>>
wrote:<br>
<br>
Hi Michael,<br>
<br>
Thanks for your message, looks interesting.<br>
<br>
However we have shown in the CAA and also Georgie
has shown it in our meetings that invariant mass of
pi+pi-\gamma<br>
resolution is much worse than missing mass of
proton. The reason is energy resolution of the
final state photon and<br>
vertex resolution as momentum of the photon is
defined through both of these, energy and vertex.<br>
Therefore we use missing mass of proton with other
cuts, which use pion mass assignment to \pi^+ and
\pi^-.<br>
<br>
Now what I have shown on Tuesday, was missing mass
of proton with electron (positron) mass assignments.<br>
There we clearly see a peak of eta. The mass
assignment is arbitrary, of course, but requirement
of missing mass squared<br>
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.<br>
And the fact that we see peak of eta is a proof that
some of pi+pi- tracks are actually e+e- pairs<br>
<br>
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<br>
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?<br>
<br>
It wouldn’t make sense for me to argue that PID on
leptons improves invariant mass e+e-\gamma, of
course it does.<br>
<br>
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<br>
from pi+pi-\gamma final state.<br>
I think we have shown that this fraction is
negligible.<br>
<br>
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<br>
acceptances these two data sets have similar or very
different numbers of eta’s.<br>
<br>
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.<br>
<br>
Best regards,<br>
Moskov.<br>
<br>
On Jul 8, 2015, at 1:33 PM, Michael C. Kunkel <<a
moz-do-not-send="true"
href="mailto:mkunkel@jlab.org">mkunkel@jlab.org</a><<a
moz-do-not-send="true"
href="mailto:mkunkel@jlab.org">mailto:mkunkel@jlab.org</a>>>
wrote:<br>
<br>
Greetings,<br>
<br>
So I was curious to reproduce my study on pion
contamination without the use of CC or EC
quantities.<br>
I am attaching a plot that shows G12 data that shows
3 lines.<br>
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<br>
<br>
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<br>
<br>
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<br>
<br>
<br>
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.<br>
<br>
Total data used:1/463 of g12 data set.<br>
<br>
Hope this helps.<br>
<br>
<br>
BR<br>
MK<br>
----------------------------------------<br>
Michael C. Kunkel, PhD<br>
Forschungszentrum Jülich<br>
Nuclear Physics Institute and Juelich Center for
Hadron Physics<br>
Experimental Hadron Structure (IKP-1)<br>
<a moz-do-not-send="true"
href="http://www.fz-juelich.de/ikp">www.fz-juelich.de/ikp</a><<a
moz-do-not-send="true"
href="http://www.fz-juelich.de/ikp">http://www.fz-juelich.de/ikp</a>><br>
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