Speaker
Dr
Alexander Borissov
(University of Glasgow, Scotland, UK)
Description
HERMES experiment at DESY has performed extensive measurements on diffractive
production of light vector mesons (rho^0, omega, phi) in the intermediate energy
region. Spin density matrix elements (SDMEs) were determined for exclusive
diffractive rho^0 and phi mesons and compared with results of high energy
experiments. Several methods for the extraction of SDMEs have been applied on the
same data sample. A comparision between those methods is given. Maximum Likelihood
method was choosed for the final computation of two sets of 23 SDMEs on hydrogen and
deuterium HERMES data. These results yield more insight in the vector meson
production mechanisms at HERMES kinematics and in the helicity transfer in
diffractive vector meson production, which allows to see new results on the s-channel
helicity violation and an indication on the contribution of unnatural parity
exchange amplitudes.
Summary
A comparision between several methods for the extraction of spin density matrix
elements of diffractive rho^0 production is given. Maximum Likelihood method was
choosed for the final computation of two sets of 23 SDMEs on hydrogen and deuterium
HERMES data. It allows to see new results on the $s$-channel helicity violation and
an indication on the contribution of unnatural parity exchange amplitudes.
Primary author
Dr
Alexander Borissov
(University of Glasgow, Scotland, UK)
