Probing Few-Body Nuclear Dynamics via ³H and ³He (e e\u27p) pn Cross-Section Measurements

We report the first measurement of the (e, e\u27p) three-body breakup reaction cross sections in helium-3 (3He) and tritium (3H) at large momentum transfer [\u3c Q2\u3e ≈ 1.9 (GeV/c)2] and xB\u3e 1 kinematics, where the cross section should be sensitive to quasielastic (QE) scattering from single nucleons. The data cover missing momenta 40 ≤ pmiss ≤ 500 MeV/c that, in the QE limit with no rescattering, equals the initial momentum of the probed nucleon. The measured cross sections are compared with state-of-the-art ab initio calculations. Overall good agreement, within ± 20%, is observed between data and calculations for the full pmiss range for 3H and for 100 ≤ pmiss ≤ 350 MeV/c for 3He. Including the effects of rescattering of the outgoing nucleon improves agreement with the data at pmiss \u3e 250 MeV/c and suggests contributions from charge-exchange (SCX) rescattering. The isoscalar sum of 3He plus 3H, which is largely insensitive to SCX, is described by calculations to within the accuracy of the data over the entire pmiss range. This validates current models of the ground state of the three-nucleon system up to very high initial nucleon momenta of 500 MeV/c