Confinement of spin and charge in high-temperature superconductors

By exploiting the internal gauge invariance intrinsic to a spin-charge-separated electron, we show that such degrees of freedom must be confined in two-dimensional superconductors experiencing strong interelectron repulsion. We also demonstrate that incipient confinement in the normal state can prevent chiral spin fluctuations from destroying the crossover between strange and pseudogap regimes in underdoped high-temperature superconductors. Last, we suggest that the negative Hall anomaly observed in these materials is connected with this confinement effect.