| In this talk I will review recent theoretical work on the so called spin (pseudo) gap phase of the high T_c cuprates. Our analysis, based on the SU(2) slave boson theory approach proposed by Wen and Lee, ascribes the incoherent line shapes seen in photoemission experiments to the presence of a new quantum fixed point for the spinons (read: spin carrying "quasiparticles" within spin-charge separation models). In this picture the coherent meanfield spinons are destroyed by massless U(1) gauge fluctuations which appear naturally in an effective low energy description of the staggered flux (sF) phase of the SU(2) mean field diagram. I will also discuss how the superconducting state with its coherent quasiparticles can be described within this approach via the opening of a mass gap in the gauge field. |