Interpretation of the dip feature in the photoemission spectra from high-Tc superconductors within the SO(5) theory

We consider a strong electronic coupling with a collective mode within the SO(5) theory for high-Tc super conductors. When applied to the superconducting state, the resulting spectral function shown to have a peak/dip/hump structure due to renormalization effects. The magnitude of the renormalization depends on the strength of the SO(5) coupling parameter. Our model is phenomenological and allows only a qualitative description, but the approach shows how the mode coupling arises in the SO(5) theory due to fluctuations allowed by the higher symmetry group.