Quantum disordered phase in a doped antiferromagnet
  A quantitative description of the transition to a quantum disordered phase in a doped antiferromagnet is obtained with a U(1) gauge-theory, where the gap in the spin-wave spectrum determines the strength of the gauge-fields. They mediate an attractive long-range interaction whose possible bound-states correspond to charge-spin separation and pairing. 
C. Kuebert and A. Muramatsu (Institut fuer theoretische Physik der   Universitaet Wuerzburg, Am Hubland, 97074 Wuerzburg, Ge...