  By involving the constraints of the slope of nuclear symmetry energy $L$ into
the question of determination of the high-density symmetry energy, one needs to
probe the curvature of nuclear symmetry energy $K_{\rm{sym}}$. Based on the
Isospin-dependent Boltzmann-Uehling-Uhlenbeck (IBUU) transport model, effects
of the curvature of nuclear symmetry energy on the squeezed-out nucleons are
demonstrated in the semi-central Au+Au reaction at 400 and 600 MeV/nucleon. It
is shown that the squeezed-out isospin-dependent nucleon emissions at high
transverse momenta are sensitive to the curvature of nuclear symmetry energy.
The curvature of nuclear symmetry energy at saturation density thus can be
determined by the high momentum squeezed-out isospin-dependent nucleon
emissions experiments from the semi-central Au+Au reaction at 400 or 600
MeV/nucleon.
