  In the past several years, we have developed a theory for the underdoped
cuprates in collaboration with X.-G. Wen, based on an SU(2) formulation of the
t-J model. In this formulation, the staggered flux state plays a central role
as the progenitor of the Neel state at half-filling and a close competitor to
the d-wave superconductor with small doping where it is characterized by
staggered orbital currents. We found support for this point of view when we
discovered fluctuating orbital currents in the Gutzwiller projected BCS
wavefunction. We shall argue that low-energy vortices, where the staggered flux
state is stabilized in the core, are needed to explain many of the unusual
properties of underdoped cuprates. Proposed experiments to look for these
orbital currents will be discussed.
