  In this paper, we provide a vacuum solution with torsion in quadratic
Riemann-curvature gravity. Physically, the solution means that vacuum can have
a nonzero vacuum field with large torsion. We show that the Einstein-Hilbert
action can be derived if we expand the quadratic curvature of the Lagrangian in
a torsion-free Riemannian space-time around a nonzero vacuum field. We also
show that the cosmological constant caused by a nonzero vacuum field is equal
to zero.
