We report the first measurement of xB-scaling in (e,e′p) cross-section ratios off nuclei relative to deuterium at large missing-momentum of 350≤pmiss≤600 MeV/c. The observed scaling extends over a kinematic range of 0.7≤xB≤1.8, which is significantly wider than 1.4≤xB≤1.8 previously observed for inclusive (e,e′) cross-section ratios. The xB-integrated cross-section ratios become constant (i.e., scale) beginning at pmiss≈kF, the nuclear Fermi momentum. Comparing with theoretical calculations we find good agreement with Generalized Contact Formalism calculations for high missing-momentum (>375 MeV/c), suggesting the observed scaling results from interacting with nucleons in short-range correlated (SRC) pairs. For low missing-momenta, mean-field calculations show good agreement with the data for pmiss≤kF, and suggest that contributions to the measured cross-section ratios from scattering off single, un-correlated, nucleons are non-negligible up to pmiss≈350 MeV/c. Therefore, SRCs become dominant in nuclei at pmiss≈350 MeV/c, well above the nuclear Fermi Surface of kF≈250 MeV/c.
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