THEORY OF NEUTRON-SCATTERING IN THE NORMAL AND SUPERCONDUCTING STATESOF YBA2CU3O6+X

We analyze neutron experiments on YBa2Cu3O6+x at various stoichiometri es in the superconducting state, within the context of a bilayer theor y that yields good agreement with the normal state Cu NMR and neutron data as a function of omega, q, and T. A d-wave superconducting state exhibits peaks at q = (pi,pi,pi) and sharp maxima as a function of ome ga, at twice the gap frequency. This behavior may have been observed e xperimentally. The counterpart behavior for other choices of order par ameter symmetry, as well as for another cuprate La1.85Sr0.15CuO4, is d iscussed.