ORTHORHOMBICITY MIXING OF S-GAP AND D-GAP COMPONENTS IN YBA2CU3O7 WITHOUT INVOLVING THE CHAINS

Momentum decoupling develops when forward scattering dominates the pai ring interaction. In this regime it is possible to obtain anisotropic s- or d-wave superconductivity even with isotropic pairing scattering. We show that in the momentum decoupling regime, the orthorhombic dist ortion of the CuO2 planes is enough to explain the experimental report s for s- mixing in the dominantly d-wave gap of YBa2Cu3O7. In the case of spin fluctuations mediated pairing instead. a large part of the co ndensate must be located in the chains in order to understand the expe riments.