Exclusive Coherent Electroproduction of the Neutral Pion Off Helium-4 and The Case for Kinematic Fitting*

We discuss the results from the exclusive coherent neutral pion electroproduction off a helium-4 target in the CLAS EG6 experiment. With event selection playing a crucial role, the beam-spin asymmetry was extracted and in agreement with a recently published general formulation of pseudoscalar (0−+) electroproduction off scalar targets. The standard use of a series of exclusivity cuts for event selection reduces much of the background but becomes inadequate for low statistics processes where background contamination becomes increasingly important. Kinematic fitting uses full detector information and 4-momenta conservation of exclusivity to select events much more cleanly. It is the events selected from kinematic fitting that are in agreement with the recent formulation. We will explore the discrepancies between the event selection methods and show that kinematic fitting is the clear choice even in the absence of recent formulation.