Direct Observation of Proton-Neutron Short-Range Correlation Dominance in Heavy Nuclei
Abstract
We measured the triple coincidence A(e,e'np) and A(e,e'pp) reactions on carbon, aluminum, iron, and lead targets at Q2 > 1.5 (GeV/c)2, xB > 1.1 and missing momentum > 400 MeV/c. This was the first direct measurement of both proton-proton (pp) and neutron-proton (np) short-range correlated (SRC) pair knockout from heavy asymmetric nuclei. For all measured nuclei, the average proton-proton (pp) to neutron-proton (np) reduced cross-section ratio is about 6%, in agreement with previous indirect measurements. Correcting for Single-Charge Exchange effects decreased the SRC pairs ratio to ~ 3%, which is lower than previous results. Comparisons to theoretical Generalized Contact Formalism (GCF) cross-section calculations show good agreement using both phenomenological and chiral nucleon-nucleon potentials, favoring a lower pp to np pair ratio. The ability of the GCF calculation to describe the experimental data using either phenomenological or chiral potentials suggests possible reduction of scale- and scheme-dependence in cross section ratios. Our results also support the high-resolution description of high-momentum states being predominantly due to nucleons in SRC pairs.
Keywords
Cite
@article{arxiv.1810.05343,
title = {Direct Observation of Proton-Neutron Short-Range Correlation Dominance in Heavy Nuclei},
author = {M. Duer and A. Schmidt and J. R. Pybus and E. P. Segarra and A. W. Denniston and R. Weiss and O. Hen and E. Piasetzky and L. B. Weinstein and N. Barnea and I. Korover and E. O. Cohen and H. Hakobyan and the CLAS Collaboration},
journal= {arXiv preprint arXiv:1810.05343},
year = {2019}
}
Comments
Accepted for publication in PRL. 9 pages, 3 figures, 3 tables and supplementary materials