Toward a reliable description of (p, pN) reactions in the distorted-wave impulse approximation

Background: Proton-induced nucleon knockout (p, pN) reactions have been successfully used to study the single-particle nature of stable nuclei in normal kinematics with the distorted-wave impulse approximation (DWIA) framework. Recently, these reactions have been applied to rare-isotope beams at intermediate energies in inverse kinematics to study the quenching of spectroscopic factors. Purpose: Our goal is to investigate the effects of various corrections and uncertainties within the standard DWIA formalism on the (p, pN) cross sections. The consistency of the extracted reduction factors between DWIA and other methods is also evaluated. Method: We analyze the (p, 2p) and (p, pn) reaction data measured at the (RB)-B-3-LAND setup at GSI for carbon, nitrogen, and oxygen isotopes in the incident energy range of 300-450 MeV/u. Cross sections and reduction factors are calculated by using the DWIA method. The transverse momentum distribution of the C-12(p, 2p)B-11 reaction is also investigated. Results: We have found that including the nonlocality corrections and the Moller factor affects the cross sections considerably. The proton-neutron asymmetry dependence of reduction factors extracted by the DWIA calculation is very weak and consistent with those given by other reaction methods and ab initio structure calculations. Conclusions: The results found in this work provide a detailed investigation of the DWIA method for (p, pN) reactions at intermediate energies. They also suggest that some higher-order effects, which is essential for an accurate cross-section description at large recoil momentum, is missing in the current DWIA and other reaction models.