[Halld-physics] Abstract to SPIN 2018

[Eugene Chudakov]

I am planning to send an abstract (enclosed) to SPIN 2018 (Sept 2018).

The main topic will be the J/psi. So far, we have shown the sigma(E)
at the Users Group meeting, but only a vague limit on the
pentaquark. Some people may be able to deduce a harder limit from the
sigma(E) plot.  Since Lubomir is planning to present nearly final
results at QNP in November, I would show in September a soft
limit.

Regards,
Eugene

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Measurement of the J/psi photoproduction cross section close to threshold

We will present preliminary results for the J/psi close-to-threshold
photoproduction obtained in the GlueX experiment at Jefferson Lab.
Close-to-threshold photoproduction gamma+p-->J/psi+p probes small-size
gluon configuration in the proton. This reaction may also contain a
contribution from the s-channel production of the LHCb pentaquark
P(4.4)-->J/psi+p at beam energies of about 10 GeV.  Measuring the
size of the contribution allows to evaluate the branching ratio of the
decay P(4.4)-->J/psi+p.
    The GlueX experiment is in the process of collecting data.  The
main research topic is the spectroscopy of light mesons produced by a
linearly polarized photon beam with the end point of 12 GeV.