Static hole in a critical antiferromagnet: field-theoretic   renormalization group
  We consider the quantum field theory of a single, immobile, spin S hole coupled to a two-dimensional antiferromagnet at a bulk quantum critical point between phases with and without magnetic long-range order. We present an alternative derivation of its two-loop beta function; the results agree completely with earlier work (M. Vojta et al, cond-mat/9912020), and also determine a new anomalous dimension of the hole creation operator. 
Subir Sachdev (Yale)