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 3Heproceeding to pdand ppnfinal states, performed in quasi-elastic kinematics at Q2=0.25 (GeV/c)2for missing momenta up to 250 MeV/c. These observables represent highly sensitive tools to investigate the electromagnetic and spin structure of 3Heand 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 3Heunless 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.