Mutual Chern-Simons effective theory of doped antiferromagnets

A mutual Chern-Simons Lagrangian is derived as a minimal field theory description of the phase-string model for doped antiferromagnets. Such an effective Lagrangian is shown to retain the full symmetries of parity, time reversal, and global SU(2) spin rotation, in contrast to conventional Chern-Simons theories where first two symmetries are usually broken. Two ordered phases---i.e., antiferromagnetic and superconducting states---are found at low temperatures as characterized by ``dual'' Meissner effects and dual-flux-quantization conditions due to the mutual Chern-Simons gauge structure. A ``dual'' confinement in charge and spin degrees of freedom occurs such that no true spin-charge separation is present in these ordered phases, but the spin-charge separation/deconfinement serves as a driving force in the unconventional phase transitions of these ordered states to disordered states.