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Dear all,<br>
<br>
Lucilla and I agree with Volker.<br>
Adding a resonance at the amplitude level results in a much
different angular behavior in the cross section<br>
than adding the resonance at the cross section level.<br>
Moreover Victor has already shown that the s1/2 resonance alone
provides an isotropic contribution to the <br>
unpolarized cross section dsigma u/domega, so that only P0 legendre
moment is expected to be non-zero<br>
for the hybrid resonance alone.<br>
Lucilla has been working on:<br>
1. comparing her code with Evgeny's to make sure we find the same
results.<br>
In attachment you find the plot of the differential cross section
dsigma_u/d(cos_theta) for Q2=0.567 GeV2<br>
and W=2.2 GeV for the Ghent model. They are in perfect agreement
now. file: Lucilla_Evgeny_comp.pdf<br>
2. Producing plots of Legendre moments for dsigma_u/domega with
different values of A_1/2 for J=1/2<br>
and A_1/2 and A_3/2 for J=3/2 with s_1/2=0.<br>
In attachment you may find the plots <br>
A1/2=0.020 and A1/2=0.040 GeV<sup class="moz-txt-sup"><span
style="display:inline-block;width:0;height:0;overflow:hidden">^</span>-1</sup>
for J=1/2+ hybrid: files Leg_A1/2=20J=1/2.pdf and
Leg_A1/2=40J=1/2.pdf<br>
and<br>
A1/2=A3/2=0.020 GeV<sup class="moz-txt-sup"><span
style="display:inline-block;width:0;height:0;overflow:hidden">^</span>-1</sup><sup> </sup><sup> </sup>
for J=3/2+ hybrid File: Leg_A1/2=A3/2=20J=3/2.pdf<br>
A1/2=0.020 GeV<sup class="moz-txt-sup"><span
style="display:inline-block;width:0;height:0;overflow:hidden">^</span>-1</sup>
A3/2=0 for J=3/2+ hybrid file: Leg_A1/2=20_A3/2=0J=3/2.pdf<br>
A1/2=0 GeV<sup class="moz-txt-sup"><span
style="display:inline-block;width:0;height:0;overflow:hidden">^</span>-1</sup>
A3/2=0.02 for J=3/2+ hybrid file: Leg_A1/2=0_A3/2=20J=3/2.pdf<br>
<br>
Many more combinations of A1/2 and A3/2 fixed values are available.<br>
<br>
<br>
3. She is also producing plots of the Legendre moments for
dsigma_TT/domega and dsigma_LT/domega<br>
We need to check the results yet, but it looks like dsigma_TT/domega
legendre moments are NOT sensitive<br>
to the addition of the hybrid resonance, while dsigma_LT/domega
legendre moments are VERY SENSITIVE<br>
to the hybrid resonance.<br>
<br>
We hope to show you the results tomorrow.<br>
All the best<br>
Lucilla and Annalisa<br>
<br>
<div class="moz-cite-prefix">Il 17/03/16 13:15, burkert ha scritto:<br>
</div>
<blockquote cite="mid:56EA9FD6.2050301@jlab.org" type="cite">Dear
all,
<br>
<br>
I am not at all surprised that the effect of L_i(Ghent + Hybrid)
is different from L_i(Ghent) + L_i(hybrid), i=1,2,3,4,5,6...
<br>
This is due to interference effects. Even if one L_i =0 for some
individual contribution, it does not have to be zero if amplitudes
are added, and L_i of the sum is evaluated. We have been making
use of interference effects for all our UIM and DR analyses. It
is also well known that interferences enhance very small effects,
e.g. the S1+/M1+ and E1+/M1+ multipole ratios for the Delta(1232)
can only be extracted due to interference effects because in the
cross section their effects are just much too small.
<br>
<br>
That does not mean, we should not verify the size of the effect in
the L_i moments as Victor suggests.
<br>
<br>
Regards,
<br>
Volker
<br>
<br>
<br>
<br>
The other question is , On 3/16/16 4:13 PM, Viktor Mokeev wrote:
<br>
<blockquote type="cite">Hi All,
<br>
<br>
In Legendre moments we may observe the structures in
W-dependencies existing simultaneously for both blue and black
curves.
<br>
<br>
In my view, the common structures we observed in W-dependence
of both blue and black curves come from Ghent amplitudes (not
from hybrid!), since they are persistent with/without hybrid.
<br>
<br>
The hybrid signal is the difference between blue and black
curves.
<br>
<br>
What is difficult for me to comprehend is: for L5 and L6
moments the hybrid moments in red look as zero within any
conceivable accuracy in the J=1/2 case. I would expect the
hybrid contributions to the moments L5,L6 should be more than
order of magnitude smaller in comparison with contributions from
Ghent model amplitudes converted to the cross sections. From the
other hand, the difference between between the blue and black
curves is sizable for the L5, L6 moments , J=1/2. I am surprised
to see that hybrid-Ghent amplitude interference at list order of
magnitude bigger than hybrid contribution.
<br>
<br>
I would propose to show superimposed in the single plot,
computed for exactly the same W and Q^2, espl, differential
dsigma_U/d(-cos\theta_K) cross sections
<br>
from Golovach ans Annalisa/Luchilla. In this plot also it is
worth to show separately hybrid contribution, Ghent contribution
(resonances + background) and coherent sum hybrid+Ghent.
<br>
<br>
Best Regards,
<br>
Victor
<br>
<br>
----- Original Message -----
<br>
From: "Viktor Mokeev" <a class="moz-txt-link-rfc2396E" href="mailto:mokeev@jlab.org"><mokeev@jlab.org></a>
<br>
To: "hybrid baryons" <a class="moz-txt-link-rfc2396E" href="mailto:hybrid_baryons@jlab.org"><hybrid_baryons@jlab.org></a>
<br>
Sent: Wednesday, March 16, 2016 10:44:16 AM
<br>
Subject: Re: [Hybrid baryons] Presentation uploaded on wiki page
<br>
<br>
Dear Annalisa and Lucilla,
<br>
<br>
Would it be possible to re-evaluate the Wigner moments in the
pp. 3-4 for
<br>
<br>
A1/2=0.030 (or 30 in your notation) GeV^-1/2 for J=1/2+ hybrid
<br>
A1/2=A3/2=0.021 (0r 21 in your notation) GeV^-1/2 J=3/2+ hybrid
<br>
<br>
THese values correspond to the threshold for hybrid
observation in observables. Nsaively. I would expect the
pronunced signal in moments with the afirementioned couplings,
since the cross hybrid cross section shpould be increasesd in
comparison with A1/2=0.004 GeV^2 you presented by a factor of
(30/4)^2=56!
<br>
<br>
Best Regards,
<br>
Victor
<br>
----- Original Message -----
<br>
From: "Lucilla Lanza" <a class="moz-txt-link-rfc2396E" href="mailto:lucilla.lanza@roma2.infn.it"><lucilla.lanza@roma2.infn.it></a>
<br>
To: "hybrid baryons" <a class="moz-txt-link-rfc2396E" href="mailto:hybrid_baryons@jlab.org"><hybrid_baryons@jlab.org></a>
<br>
Sent: Tuesday, March 15, 2016 7:09:07 AM
<br>
Subject: [Hybrid baryons] Presentation uploaded on wiki page
<br>
<br>
Dear all,
<br>
<br>
we uploaded our last presentation on the Hybrid Baryons wiki
page.
<br>
<br>
Best regards,
<br>
<br>
Annalisa and Lucilla
<br>
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<pre class="moz-signature" cols="72">--
================================================
Prof. Annalisa D'Angelo
Dip. Fisica, Universita' di Roma "Tor Vergata"
INFN Sezione di Roma Tor Vergata, Rome Italy
<a class="moz-txt-link-abbreviated" href="mailto:email:annalisa.dangelo@roma2.infn.it">email:annalisa.dangelo@roma2.infn.it</a>
Jefferson Laboratory, Newport News, VA USA
Email: <a class="moz-txt-link-abbreviated" href="mailto:annalisa@jlab.org">annalisa@jlab.org</a>
Tel: + 39 06 72594562
Fax: + 39 06 2040309</pre>
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