We calculate the elastic form factors and the generalized parton distributions (GPDs) for four low-lying bound states of a demonstration fermion-antifermion system, strong-coupling positronium (eē), using basis light-front quantization (BLFQ). By using this approach, we also calculate the impact-parameter-dependent GPDs q(x,b) to visualize the fermion density in the transverse plane (b). We compare selected results with corresponding quantities in the nonrelativistic limit to reveal relativistic effects. Our results establish the foundation within BLFQ for investigating the form factors and the GPDs for hadronic systems.
Bibliographical noteFunding Information:
This work was supported in part by the US Department of Energy under Grants No. DE-FG02-87ER40371 and No. DESC0008485 (SciDAC-3/NUCLEI). X. Zhao is supported by new faculty startup funding by the Institute of Modern Physics, Chinese Academy of Sciences. Computational resources were provided by the National Energy Research Scientific Computing Center (NERSC), which is supported by the Office of Science of the US Department of Energy under Contract No. DE-AC02-05CH11231.
© 2016 American Physical Society.