Novel neutron resonance mode in dx2-y2-wave superconductors -: art. no. 147001

We show that a new resonant magnetic excitation at incommensurate momenta, observed recently by inelastic neutron scattering experiments on YBa(2)Cu(3)O(6.85) and YBa(2)Cu(3)O(6.6), is a spin exciton. Its location in the Brillouin zone and its frequency are determined by the momentum dependence of the particle-hole continuum. We identify several features that distinguish this novel mode from the previous resonance mode observed near Q=(pi,pi).