München 2019 – wissenschaftliches Programm
HK 54.3: Poster
Donnerstag, 21. März 2019, 16:30–19:00, Foyer Theresanium
Extraction of Asin(φ)LU moments from the hard exclusive π+ channel off the unpolarized hydrogen target in a wide range of kinematics with CLAS at 5.5 GeV — •Stefan Diehl for the CLAS collaboration — University of Connecticut, Storrs, USA — Justus Liebig University Giessen, Giessen, Germany
For the first time, we have measured single beam spin asymmetries to extract Asin(φ)LU moments from the hard exclusive π+ channel off the unpolarized hydrogen target in a wide range of kinematics from forward angles to backward angles in the center of mass frame. The measured moment in forward angles is known to be sensitive to generalized parton distributions (GPDs), while in backward angles, it is known to be sensitive to transition distribution amplitudes (TDAs). Our results clearly show that the sign of forward beam spin asymmetry measurements is positive whereas that of backward BSA measurements is negative, with the sign transition taking place around 90 degrees. By performing accurate measurements over a wide range of Q2 and t, we can explore the transition from hadronic to partonic reaction mechanisms.
*The work is supported by DOE grant no: DE-FG02-04ER41309.