Deconfined quantum criticality driven by Dirac fermions in SU(2) antiferromagnets

Quantum electrodynamics in 2+1 dimensions is an effective gauge theory for the so-called algebraic quantum liquids. A new type of such a liquid, the algebraic charge liquid, has been proposed recently in the context of deconfined quantum critical points [R. K. Kaul et al., Nat. Phys. 4, 28 (2008)]. In this context, by using the renormalization group in d=4-epsilon space-time dimensions, we show that a deconfined quantum critical point occurs in a SU(2) system provided the number of Dirac fermion species N-f >= 4. The calculations are done in a representation where the Dirac fermions are given by four-component spinors. The critical exponents are calculated for several values of N-f. In particular, for N-f=4 and epsilon=1 (d=2+ 1), the anomalous dimension of the Neel field is given by eta(N)=1/3, with a correlation length exponent v = 1/2. These values considerably change for N-f > 4. For instance, for N-f = 6, we find eta(N) approximate to 0.75 191 and v approximate to 0.660 09. We also investigate the effect of chiral symmetry breaking and analyze the scaling behavior of the chiral holon susceptibility, G(x)(x) equivalent to <(Psi) over bar (x)Psi(x)(Psi) over bar (0)Psi(0)>.