[Halld-physics] Reading Group Friday

[Eugene Chudakov]

There is a collection of various links concerning J/psi
close-to-threshold photoproduction (see "meeting, talks") as well as
the older papers:

https://userweb.jlab.org/~gen/charm/

A few numbers:

The expected gamm+p-->J/psi+p cross section at 10 GeV is about 0.1nb.
The lowest Cornell point was about 0.5nb for <12 GeV. This led Brodsky
to speculate that there could be some anomaly.

We do not know the gamma+p-->P-->J/psi rate, but may assume, as the
starting point, the same ratio to non-resonance J/psi+p events as LHCB
had for the LB spectrum.  They had about 500 events per 15MeV bin. For
the incoming photon it would be an 80 MeV bin.

Assuming 0.1nb I estimated that one can get about 1600 events/bin in
Hall C (based on PR12-07-006 proposal)) and 100 events in Hall B
(based on PR12-12-001 proposal) for a 3-month run.

For GlueX at "low" intensity and the regular running (peak at 9 GeV
and 3mm hole) it would be about 2 ev/bin. Using the 5mm hole and 5
times more current would give about 20 ev/bin.

Eugene



------------------------------------------------------
Eugene Chudakov
https://userweb.jlab.org/~gen/
phone (757) 269 6959  fax (757) 269 6331
Thomas Jefferson National Accelerator Facility
12000 Jefferson Ave, STE 4,
Newport News, VA 23606 USA

On Fri, 7 Aug 2015, Richard Jones wrote:

> Matt,
>
> As this paper makes clear, Reinhard's idea of looking for this state in
> formation mode with GlueX at 10GeV is well within reach. Of course the BR
> to J/Psi,p might be miniscule but if so then why would this be the first
> mode in which it has been seen? My comment to Reinhard last Friday that
> searching for ccbar baryons in GlueX would be a long shot was incorrect.
>
> -Richard Jones
>
> On Wed, Jul 22, 2015 at 11:11 AM, Shepherd, Matthew <mashephe at indiana.edu>
> wrote:
>
>>
>> Hi all,
>>
>> We decided to break momentarily from the photoproduction theme to read and
>> discuss this timely paper from LHCb on pentaquarks with hidden charm.
>>
>> http://arxiv.org/abs/1507.03414
>>
>> Let’s meet Friday at 3:30 in F326/7.  Focus primarily on the article
>> itself, which is the first 15 pages.
>>
>> Please bring questions and topics for discussion!
>>
>> Matt
>>
>> ---------------------------------------------------------------------
>> Matthew Shepherd, Associate Professor
>> Department of Physics, Indiana University, Swain West 265
>> 727 East Third Street, Bloomington, IN 47405
>>
>> Office Phone:  +1 812 856 5808
>>
>>
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>