Backward-angle Exclusive pi0 Production above the Resonance Region
Abstract
The proposed measurement is a dedicated study of the exclusive electroproduction process,1H(e,e'p)pi0, in the backward-angle regime (u-channel process) above the resonance region. The produced pi0 is emitted 180 degrees opposite to the virtual-photon momentum. This study also aims to apply the well-known Rosenbluth separation technique that provides the model-independent differential cross-sections at the never explored u-channel kinematics region. Currently, the "soft-hard transition" in u-channel meson production remains an interesting and unexplored subject. The available theoretical frameworks offer competing interpretations for the observed backward-angle cross section peaks. In a "soft" hadronic Regge exchange description, the backward meson production comes from the interference between nucleon exchange and the meson produced via re-scattering within the nucleon. Whereas in the "hard" GPD-like backward collinear factorization regime, the scattering amplitude factorizes into a hard subprocess amplitude and baryon to meson transition distribution amplitudes (TDAs), otherwise known as super skewed parton distributions (SuperSPDs). Both TDAs and SPDs are universal non-perturbative objects of nucleon structure accessible only through backward-angle kinematics. The separated cross sections:sigma_T,sigma_L and T/L ratio at Q2=2-6 GeV2, provide a direct test of two predictions from the TDA model. The magnitude and u-dependence of the separated cross sections also provide a direct connection to the re-scattering Regge picture. The extracted interaction radius (from u-dependence) at different Q2 can be used to study the soft-hard transition in the u-channel kinematics. The acquisition of these data will be an important step forward in validating the existence of a backward factorization scheme of the nucleon structure function and establishing its applicable kinematic range.
Keywords
Cite
@article{arxiv.2008.10768,
title = {Backward-angle Exclusive pi0 Production above the Resonance Region},
author = {W. B. Li and G. M. Huber and J. R. Stevens and K. Semenov-Tian-Shansky and L. Szymanowski and B. Pire and M. Amaryan and D. Androic and K. Aniol and D. Armstrong and T. Averett and C. Ayerbe Gayoso and W. Boeglin and M. Boer and A. Camsonne and J. Chen and S. Covrig Dusa and W. Deconinck and M. Defurne and F. Delcarro and M. Diefenthaler and S. Diehl and M. Elaasar and C. Fanelli and S. Fegan and E. Fuchey and D. Gaskell and O. Hansen and F. Hauenstein and D. Higinbotham and A. Hiller Blin and A. Hurley and C. Hyde and K. Joo and M. Junaid and N. Kalantarians and S. Kay and M. Khachatryan and P. King and V. Kumar and D. Lersch and L. Lorenti and P. Markowitz and M. McCaughan and A. Mkrtchyan and H. Mkrtchyan and G. Niculescu and I. Niculescu and Z. Papandreou and R. Paremuzyan and K. Park and D. Paudyal and J. Roche and A. Rodas and B. Sawatzky and A. Schertz and G. Smith and I. Strakovsky and V. Tadevosyan and A. Usman and H. Voskanyan and C. Yero},
journal= {arXiv preprint arXiv:2008.10768},
year = {2021}
}