Phenomenological description of the two energy scales in underdoped superconducting cuprates

Raman and ARPES experiments have demonstrated that in superconducting underdoped cuprates nodal and antinodal regions are characterized by two energy scales instead of the one expected in BCS. The nodal scale decreases with underdoping while the antinodal one increases. Contrary to the behavior expected for an increasing energy scale, the antinodal Raman intensity decreases with decreasing doping. Using the Yang, Rice and Zhang (YRZ) model, we show that these features are a consequence of the non-conventional nature of the superconducting state in which superconductivity and pseudogap correlations are both present and compete for the phase space.