COULOMB INTERACTIONS AT QUANTUM HALL CRITICAL-POINTS OF SYSTEMS IN A PERIODIC POTENTIAL

We study the consequences of long-range Coulomb interactions at the cr itical points between integer/fractional quantum Hall states and an in sulator. We use low energy theories for such transitions in anyon gase s in the presence of an external periodic potential. We find that Coul omb interactions are marginally irrelevant for the integer quantum Hal l case. For the fractional case, depending upon the anyon statistics p arameter, we find behavior similar to the integer case, or flow to a n ovel line of fixed points with exponents z = 1, nu > 1 stable against weak disorder in the position of the critical point, or runaway flow t o strong coupling.