We show that several features (the three-dimensional XY universality for
moderate underdoping, the almost-BCS behaviour for moderate overdoping and the
critical exponent) of the superfluid density in hole-doped cuprates hint at a
composite structure of the holes. This idea can be implemented in a spin-charge
gauge approach to the t−t′−J model and provides indeed good agreement
with available experimental data.Comment: 5 pages, 1 figure, to be published in the proceedings of the
International Conference in Superconductivty and Magnetism ICSM201
