English

Charged pion electroproduction above the resonance region

Nuclear Theory 2014-03-05 v1 High Energy Physics - Phenomenology

Abstract

[Background] Above the nucleon resonance region, the N(e,eπ±)NN(e,e'\pi^\pm)N' data cannot be explained by conventional hadronic models. For example, the observed magnitude of the transverse cross section is significantly underestimated in a framework with Reggeized background amplitudes. [Purpose] Develop a phenomenological framework for the N(e,eπ±)NN(e,e'\pi^\pm)N' reaction at high invariant mass WW and deep photon virtuality Q2Q^2. [Method] Building on the work of Kaskulov and Mosel, a gauged pion-exchange current is introduced with a running cutoff energy for the proton electromagnetic transition form factor. A new transition form factor is proposed. It respects the correct on-shell limit, has a simple physical interpretation and reduces the number of free parameters by one. [Results] A study of the WW dependence of the N(e,eπ±)NN(e,e'\pi^\pm)N' lends support for the newly proposed transition form factor. In addition, an improved description of the separated and unseparated cross sections at t0.5  GeV2-t \lesssim 0.5 \;\text{GeV}^2 is obtained. The predictions overshoot the measured unseparated cross sections for t>0.5  GeV2-t > 0.5 \;\text{GeV}^2. Introducing a strong hadronic form factor in the Reggeized background amplitudes brings the calculations considerably closer to the high t-t data. [Conclusions] Hadronic models corrected for resonance/parton duality describe the separated pion electroproduction cross sections above the resonance region reasonably well at low t-t. In order to validate the applicability of these models at high t-t, separated cross sections are needed. These are expected to provide a more profound insight into the relevant reaction mechanisms.

Keywords

Cite

@article{arxiv.1310.7715,
  title  = {Charged pion electroproduction above the resonance region},
  author = {Tom Vrancx and Jan Ryckebusch},
  journal= {arXiv preprint arXiv:1310.7715},
  year   = {2014}
}

Comments

11 pages, 8 figures