Cross section measurements of charged pion photoproduction in hydrogen and deuterium from 1.1 to 5.5 GeV

Abstract

The differential cross section for the {gamma}n {yields} {pi}{sup -}p and the {gamma}p {yields} {pi}{sup +}n processes were measured at Jefferson Lab. The photon energies ranged from 1.1 to 5.5 GeV, corresponding to center-of-mass energies from 1.7 to 3.4 GeV. The pion center-of-mass angles varied from 50 degree to 110 degree. The {pi}{sup -} and {pi}{sup +} photoproduction data both exhibit a global scaling behavior at high energies and high transverse momenta, consistent with the constituent counting rule prediction and the existing {pi}{sup +} data. The data suggest possible substructure of the scaling behavior, which might be oscillations around the scaling value. The data show an enhancement in the scaled cross section at center-of-mass energy near 2.2 GeV. The differential cross section ratios at high energies and high transverse momenta can be described by calculations based on one-hard-gluon-exchange diagrams.