Application of Maximum Likelihood Method for the computation of Spin Density Matrix Elements of Vector Meson Production at HERMES.
Presented by Dr. Alexander BORISSOV on 13 Feb 2006 from 11:00 to 11:20
Track: Event processing applications
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.