On narrow nucleon excitation N*(1685)
V. Kuznetsov+, M. V. Polyakov° *, M. Thürmann*
+Institute for Nuclear Research, 117312 Moscow, Russia
°Institut für Theoretische Physik II, Ruhr-Universität Bochum, D-44780 Bochum, Germany
*St. Petersburg Institute for Nuclear Physics, 188300 St. Petersburg, Russia
Abstract
We perform estimates on putative narrow
nucleon N*(1685) - the
candidate for the non-strange member of the exotic anti-decuplet of baryons. In particular,
we
consider the recent high precision data on η photoproduction off free proton obtained
by
the Crystal Ball Collaboration at MAMI. We show that
it is difficult to describe peculiarities of
these new data in the invariant energy interval of
MeV in terms
of known wide resonances. Using very simple estimates, we show that the data
may indicate an existence of a narrow N*(1685) with small photocoupling to the
proton.