We report on a precise measurement of double-polarization asymmetries in
electron-induced breakup of $^3\mathrm{He}$ proceeding to $\mathrm{pd}$ and
$\mathrm{ppn}$ final states, performed in quasi-elastic kinematics at $Q^2 =
0.25\,(\mathrm{GeV}/c)^2$ for missing momenta up to $250\,\mathrm{MeV}/c$.
These observables represent highly sensitive tools to investigate the
electromagnetic and spin structure of $^3\mathrm{He}$ 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 $^3\mathrm{He}$ 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.
