DOI: 10.1140/epjc/s2003-01232-3
Double-spin asymmetries in the cross section
of
and
production at intermediate energies
The HERMES Collaboration (Received: 11 February 2003 / Published online: 11 June 2003 )
Abstract
Double-spin asymmetries in the cross section of electroproduction of
and
mesons on
the proton and deuteron are measured at the HERMES experiment.
The photoabsorption asymmetry in exclusive
electroproduction on the proton exhibits
a positive tendency. This is consistent with theoretical predictions that the exchange
of an object with unnatural parity contributes to exclusive
electroproduction by
transverse photons. The photoabsorption asymmetry on the deuteron is found to be
consistent with zero.
Double-spin asymmetries in
and
meson electroproduction by quasi-real photons
were also found to be consistent with zero; the asymmetry in the case of the
meson is compatible with a theoretical prediction which involves
knockout from the nucleon.
© Società Italiana di Fisica, Springer-Verlag 2003
