<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">I am still not sure I understand the numbers in the Karliner/Rosner paper, but they have peak<div class="">cross sections in the ub (micro barn) range, not the nb range for J/Psi production. This is probably</div><div class="">when I first started hearing about this, I assumed that the rates we could observe with nb or smaller</div><div class="">cross sections would make this incredibly hard to pull out. If a ub cross section is real, this would</div><div class="">stand out pretty clearly in our data.</div><div class=""><br class=""></div><div class="">Curtis<br class=""><div apple-content-edited="true" class="">
<span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div class=""><div class="">---------</div><div class="">Curtis A. Meyer<span class="Apple-tab-span" style="white-space: pre; "> </span>MCS Associate Dean for Faculty and Graduate Affairs</div><div class="">Wean: (412) 268-2745<span class="Apple-tab-span" style="white-space: pre; "> </span>Professor of Physics</div><div class="">Doherty: (412) 268-3090<span class="Apple-tab-span" style="white-space: pre; "> </span>Carnegie Mellon University</div><div class="">Fax: (412) 681-0648<span class="Apple-tab-span" style="white-space: pre; "> </span>Pittsburgh, PA 15213</div><div 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/</div></div><div class=""><br class=""></div></span><br class="Apple-interchange-newline">
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<br class=""><div><blockquote type="cite" class=""><div class="">On Aug 7, 2015, at 12:31 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 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=""><a href="https://userweb.jlab.org/~gen/charm/" class="">https://userweb.jlab.org/~gen/charm/</a><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=""><br class=""><br class="">_______________________________________________<br class="">Halld-physics mailing list<br class="">Halld-physics@jlab.org<br class="">https://mailman.jlab.org/mailman/listinfo/halld-physics<br class=""></blockquote></blockquote>_______________________________________________<br class="">Halld-physics mailing list<br class="">Halld-physics@jlab.org<br class="">https://mailman.jlab.org/mailman/listinfo/halld-physics</div></blockquote></div><br class=""></div></body></html>