A Gaussian effective theory for gluon saturation Original Research Article

We construct a Gaussian approximation to the effective theory for the colour glass condensate which describes correctly the gluon distribution both in the low density regime at high transverse momenta (above the saturation scale Qs), and in the high density regime below Qs, and provides a simple interpolation between these two regimes. At high momenta, the effective theory reproduces the BFKL dynamics, while at low momenta, it exhibits gluon saturation and, related to it, colour neutrality over the short distance scale 1/Qs⪡1/ΛQCD. Gauge-invariant quantities computed within this approximation are automatically infrared-finite.