QUANTUM TRANSPORT IN 2-CHANNEL FRACTIONAL QUANTUM HALL EDGES

We study the effect of backward scatterings in the tunneling at a poin t contact between the edges of second-level hierarchical fractional qu antum Hall states. A universal scaling dimension of the tunneling cond uctance is obtained only when both of the edge channels propagate in t he same direction, It is shown that the quasiparticle-tunneling pictur e and the electron-tunneling picture give different scaling behaviors of the conductances, which indicates the existence of a crossover betw een the two pictures. When the direction of two edge channels are oppo site, e.g., in the case of MacDonald's edge construction for the nu = 2/3 state [Phys. Rev. Lett. 64, 220 (1990)], the phase diagram is divi ded into two domains giving a different temperature dependence of the conductance.