4 — d expansion for Anderson localization in a strong spin-orbit coupling case

The problem of Anderson localization in a strong spin-orbit coupling case is studied by using a gauge invariant matrix model in e=4-d expansion. An infrared stable fixed point is present and this model belongs to the same universal class as a nonlinear σ model. An expression for the critical exponent of conductivity is obtained in the first order of the e-expansion Etude de cette localisation a l'aide d'un modele matriciel a invariance de jauge: presence d'un point fixe stable dans l'IR et appartenance du modele a la meme classe d'universalite que le modele σ non lineaire. Expression pour l'exposant de la conductivite au 1er ordre en e