title: Criticality in the (2+1)-dimensional compact Higgs model and fractionalized insulators.
abstract: We use a novel method of computing the third moment M3 of the action of the (2+1)-dimensional compact Higgs model in the adjoint representation with q=2 to extract correlation length and specific heat exponents nu and alpha without invoking hyperscaling. Finite-size scaling analysis of M3 yields the ratios (1+alpha)/nu and 1/nu separately. We find that alpha and nu vary along the critical line of the theory, which however exhibits a remarkable resilience of Z2 criticality. We propose this novel universality class to be that of the quantum phase transition from a Mott-Hubbard insulator to a charge-fractionalized insulator in two spatial dimensions.
authors.affiliation: Department of Physics, Norwegian University of Science and Technology, N-7491 Trondheim, Norway.
authors.forename: A
authors.initials: A
authors.lastname: Sudbø
authors.forename: E
authors.initials: E
authors.lastname: Smørgrav
authors.forename: J
authors.initials: J
authors.lastname: Smiseth
authors.forename: F S
authors.initials: FS
authors.lastname: Nogueira
authors.forename: J
authors.initials: J
authors.lastname: Hove