Probing few-body nuclear dynamics via $^3$H and $^3$He $(e,e’p)$pn cross-section mesurements

We will report the first measurement of the (e,e’p) three-body breakup reaction cross sections in helium-3 ($^3$He) and tritium ($^3$3H) at large momentum transfer ($Q^2$~1.9 (GeV/c)$^2$) and ($x_B > 1$) kinematics, where the cross-section should be sensitive to quasielastic (QE) scattering from single nucleons. The data cover missing momenta $40 < p_{miss} < 500$ 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 $^3$H and for $100 < p_{miss} < 350$ MeV/c for $^3$He. Including the effects of rescattering of the outgoing nucleon improves agreement with the data at $p_{miss} > 250$ MeV/c and suggests contributions from charge-exchange (SCX) rescattering. The isoscalar sum of $^3$He plus $^3$H, which is largely insensitive to SCX, is described by calculations to within the accuracy of the data over the entire $p_{miss}$ 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.