Quantum critical points with the Coulomb interaction and the dynamical exponent: when and why z = 1.
A general scenario that leads to Coulomb quantum criticality with the dynamical critical exponent z = 1 is proposed. I point out that the long-range Coulomb interaction and quenched disorder have competing effects on z, and that balance between the two may lead to charged quantum critical points at which z = 1 exactly. This is illustrated with the calculation for the Josephson junction array Hamiltonian in dimensions D = 3 - epsilon. Precisely in D = 3, however, the above simple result breaks down, and z > 1. Relation to other studies is discussed.
Herbut
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IF
Department of Physics, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6.