Measurement of double-polarization asymmetries in the quasi-elastic He→3(e→,e'p) process

We report on a precise measurement of double-polarization asymmetries in electron-induced breakup of He-3 proceeding to pd and ppn final states, performed in quasi-elastic kinematics at Q(2) = 0.25 (GeV/c)(2) for missing momenta up to 250 MeV/c. These observables represent highly sensitive tools to investigate the electromagnetic and spin structure of He-3 and the relative importance of two- and three-body effects involved in the breakup reaction dynamics. The measured asymmetries cannot be satisfactorily reproduced by state-of-the-art calculations of He-3 unless their three-body segment is adjusted, indicating that the spin-dependent part of the nuclear interaction governing the three-body breakup process is much smaller than previously thought. (C) 2018 The Author. Published by Elsevier B.V.