English

Virtual Compton Scattering measurements in the nucleon resonance region

Nuclear Experiment 2020-01-08 v2

Abstract

We report on new measurements of the electric Generalized Polarizability (GP) of the proton αE\alpha_E in a kinematic region where a puzzling dependence on momentum transfer has been observed, and we have found that αE=(5.3±0.6stat±1.3sys) 104fm3\alpha_E = (5.3 \pm 0.6_{stat} \pm 1.3_{sys})~10^{-4} fm^3 at Q2=0.20 (GeV/c)2Q^2=0.20~(GeV/c)^2. The new measurements, when considered along with the rest of the world data, suggest that αE\alpha_E can be described by either a local plateau or by an enhancement in the region Q2=0.20 (GeV/c)2Q^2=0.20~(GeV/c)^2 to 0.33 (GeV/c)20.33~(GeV/c)^2. The experiment also provides the first measurement of the Coulomb quadrupole amplitude in the NΔN \rightarrow \Delta transition through the exploration of the p(e,ep)γp(e,e'p)\gamma reaction. The new measurement gives CMR=(4.4±0.8stat±0.6sys) %CMR = (-4.4 \pm 0.8_{stat} \pm 0.6_{sys})~\% at Q2=0.20 (GeV/c)2Q^2=0.20~(GeV/c)^2 and is consistent with the results from the pion electroproduction world data. It has been obtained using a completely different extraction method, and therefore represents a strong validation test of the world data model uncertainties.

Keywords

Cite

@article{arxiv.1901.08951,
  title  = {Virtual Compton Scattering measurements in the nucleon resonance region},
  author = {A. Blomberg and H. Atac and N. Sparveris and M. Paolone and P. Achenbach and M. Benali and J. Beričič and R. Böhm and L. Correa and M. O. Distler and A. Esser and D. Flay and H. Fonvieille and I. Friščić and Y. Kohl and H. Merkel and U. Müller and Z. E. Meziani and M. Mihovilovic and J. Pochodzalla and A. Polychronopoulou and B. Pasquini and M. Schoth and F. Schulz and S. Schlimme and C. Sfienti and S. Sirca and A. Weber},
  journal= {arXiv preprint arXiv:1901.08951},
  year   = {2020}
}