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.

Original languageEnglish
Article number172502
JournalPhysical Review Letters
Volume122
Issue number17
DOIs
StatePublished - 3 May 2019

Funding

FundersFunder number
Chilean Comisin Nacional de Investigacin Cientfica y Tecnolgica
French Centre National de la Recherche Scientifique and Commissariat a l’Energie Atomique the French-American Cultural Exchange
Office of Nuclear Physics
National Science Foundation1812382
U.S. Department of Energy
Office of Science
Thomas Jefferson National Accelerator Facility
Science and Technology Facilities CouncilST/P004385/1
National Research Foundation of Korea
Israel Science Foundation
PAZY Foundation
Istituto Nazionale di Fisica Nucleare

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