paper

Critical behavior of the QED-Gross-Neveu model: Duality and deconfined criticality

arXiv:1708.02256 · doi:10.1103/PhysRevB.96.205113

Abstract

We study the critical properties of the QED-Gross-Neveu model with flavors of two-component Dirac fermions coupled to a massless scalar field and a U(1) gauge field. For , this theory has recently been suggested to be dual to the SU(2) noncompact CP model that describes the deconfined phase transition between the Neel antiferromagnet and the valence bond solid on the square lattice. For , the theory has been proposed as an effective description of a deconfined critical point between chiral and Dirac spin liquid phases, and may potentially be realizable in spin- systems on the kagome lattice. We demonstrate the existence of a stable quantum critical point in the QED-Gross-Neveu model for all values of . This quantum critical point is shown to escape the notorious fixed-point annihilation mechanism that renders plain QED (without scalar-field coupling) unstable at low values of . The theory exhibits an upper critical space-time dimension of four, enabling us to access the critical behavior in a controlled expansion in the small parameter . We compute the scalar-field anomalous dimension , the correlation-length exponent , as well as the scaling dimension of the flavor-symmetry-breaking bilinear at the critical point, and compare our leading-order estimates with predictions of the conjectured duality.

12 pages, 7 figures, 1 table; v2: loop diagrams added, additional comments and references, published version

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