Flux quantization for a vortex in two-gap superconductor
  Contrary to recent theoretical prediction, we show that the magnetic flux of a vortex in SU(2) model of two-gap superconductor is quantized in units of 2\pi/g, not 4 \pi/g. For the U(1) version of this model, the flux is quantized in units of 2 \pi\alpha/g where 0 < \alpha < 1. The parameter \alpha depends on the masses and concentrations of the Cooper pairs in the two condensates. 
Eugen Simanek