  In this paper, we study the existence of least energy sign-changing solutions
for a Kirchhoff-type problem involving the fractional Laplacian operator. By
using the constraint variational method and quantitative deformation lemma, we
obtain a least energy nodal solution ub for the given problem. Moreover, we
show that the energy of ub is strictly larger than twice the ground state
energy. We also give a convergence property of u_b as b goes to 0, where b is
regarded as a parameter.
