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Also see figure 7 in this
<div class=""><a href="http://arxiv.org/pdf/hep-ex/9712027v1.pdf" class="">http://arxiv.org/pdf/hep-ex/9712027v1.pdf</a></div>
<div class="">for more J/psi photoproduction data.</div>
<div class=""><br class="">
</div>
<div class="">Ryan</div>
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<div class=""><br class="">
<div>
<blockquote type="cite" class="">
<div class="">On Aug 7, 2015, at 1:44 PM, Eugene Chudakov <<a href="mailto:gen@jlab.org" class="">gen@jlab.org</a>> wrote:</div>
<br class="Apple-interchange-newline">
<div class="">There is not much room for a large cross section times BR, because of<br class="">
the existing measurements of J/psi photoproduction (Cornell), which<br class="">
integrated the incoming photon energies. A 100MeV full width bump<br class="">
produced at 1ub and decaying 100% to J/psi+p would produce 1000 times<br class="">
more J/psi-s than observed.<br class="">
<br class="">
A very high cross section for gamma+p-->P should be seen in the Compton scattering (Moskov is looking into it).<br class="">
<br class="">
Eugene<br class="">
<br class="">
On Fri, 7 Aug 2015, Curtis A. Meyer wrote:<br class="">
<br class="">
<blockquote type="cite" class="">I am still not sure I understand the numbers in the Karliner/Rosner paper, but they have peak<br class="">
cross sections in the ub (micro barn) range, not the nb range for J/Psi production. This is probably<br class="">
when I first started hearing about this, I assumed that the rates we could observe with nb or smaller<br class="">
cross sections would make this incredibly hard to pull out. If a ub cross section is real, this would<br class="">
stand out pretty clearly in our data.<br class="">
<br class="">
Curtis<br class="">
---------<br class="">
Curtis A. Meyer<span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"></span><span class="Apple-tab-span" style="white-space:pre"></span>MCS Associate Dean for Faculty and Graduate Affairs<br class="">
Wean: (412) 268-2745<span class="Apple-tab-span" style="white-space:pre"> </span>
Professor of Physics<br class="">
Doherty: (412) 268-3090<span class="Apple-tab-span" style="white-space:pre"> </span>
Carnegie Mellon University<br class="">
Fax: (412) 681-0648<span class="Apple-tab-span" style="white-space:pre"> </span>
Pittsburgh, PA 15213<br class="">
<a href="mailto:curtis.meyer@cmu.edu" class="">curtis.meyer@cmu.edu</a><span class="Apple-tab-span" style="white-space:pre">
</span>http://www.curtismeyer.com/<br class="">
<br class="">
<br class="">
<br class="">
<blockquote type="cite" class="">On Aug 7, 2015, at 12:31 PM, Eugene Chudakov <gen@jlab.org> wrote:<br class="">
<br class="">
There is a collection of various links concerning J/psi<br class="">
close-to-threshold photoproduction (see "meeting, talks") as well as<br class="">
the older papers:<br class="">
<br class="">
https://userweb.jlab.org/~gen/charm/<br class="">
<br class="">
A few numbers:<br class="">
<br class="">
The expected gamm+p-->J/psi+p cross section at 10 GeV is about 0.1nb.<br class="">
The lowest Cornell point was about 0.5nb for <12 GeV. This led Brodsky<br class="">
to speculate that there could be some anomaly.<br class="">
<br class="">
We do not know the gamma+p-->P-->J/psi rate, but may assume, as the<br class="">
starting point, the same ratio to non-resonance J/psi+p events as LHCB<br class="">
had for the LB spectrum. They had about 500 events per 15MeV bin. For<br class="">
the incoming photon it would be an 80 MeV bin.<br class="">
<br class="">
Assuming 0.1nb I estimated that one can get about 1600 events/bin in<br class="">
Hall C (based on PR12-07-006 proposal)) and 100 events in Hall B<br class="">
(based on PR12-12-001 proposal) for a 3-month run.<br class="">
<br class="">
For GlueX at "low" intensity and the regular running (peak at 9 GeV<br class="">
and 3mm hole) it would be about 2 ev/bin. Using the 5mm hole and 5<br class="">
times more current would give about 20 ev/bin.<br class="">
<br class="">
Eugene<br class="">
<br class="">
<br class="">
<br class="">
------------------------------------------------------<br class="">
Eugene Chudakov<br class="">
https://userweb.jlab.org/~gen/<br class="">
phone (757) 269 6959 fax (757) 269 6331<br class="">
Thomas Jefferson National Accelerator Facility<br class="">
12000 Jefferson Ave, STE 4,<br class="">
Newport News, VA 23606 USA<br class="">
<br class="">
On Fri, 7 Aug 2015, Richard Jones wrote:<br class="">
<br class="">
<blockquote type="cite" class="">Matt,<br class="">
<br class="">
As this paper makes clear, Reinhard's idea of looking for this state in<br class="">
formation mode with GlueX at 10GeV is well within reach. Of course the BR<br class="">
to J/Psi,p might be miniscule but if so then why would this be the first<br class="">
mode in which it has been seen? My comment to Reinhard last Friday that<br class="">
searching for ccbar baryons in GlueX would be a long shot was incorrect.<br class="">
<br class="">
-Richard Jones<br class="">
<br class="">
On Wed, Jul 22, 2015 at 11:11 AM, Shepherd, Matthew <mashephe@indiana.edu><br class="">
wrote:<br class="">
<br class="">
<blockquote type="cite" class=""><br class="">
Hi all,<br class="">
<br class="">
We decided to break momentarily from the photoproduction theme to read and<br class="">
discuss this timely paper from LHCb on pentaquarks with hidden charm.<br class="">
<br class="">
http://arxiv.org/abs/1507.03414<br class="">
<br class="">
Let’s meet Friday at 3:30 in F326/7. Focus primarily on the article<br class="">
itself, which is the first 15 pages.<br class="">
<br class="">
Please bring questions and topics for discussion!<br class="">
<br class="">
Matt<br class="">
<br class="">
---------------------------------------------------------------------<br class="">
Matthew Shepherd, Associate Professor<br class="">
Department of Physics, Indiana University, Swain West 265<br class="">
727 East Third Street, Bloomington, IN 47405<br class="">
<br class="">
Office Phone: +1 812 856 5808<br class="">
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