PATH-INTEGRAL ANALYSIS OF BOSONS INTERACTING WITH A GAUGE FIELD

We analyze an effective action of bosons moving in a fluctuating gauge field, which describes the motion of the holons in the t-J model. The analysis is in terms of a dimensionless coupling constant, g approxim ately 24pit/J. We use a path-integral approach, which is a convenient method in the strong-coupling limit g much greater than 1. The effect of the gauge field is to suppress boson loops that enclose a large are a, so that the main contribution comes from almost self-retracing path s. By taking a quenched average over the gauge field we are able to de rive a renormalized density of states that has a shifted band edge, an d that is enhanced near the band edge. We also find an expression for the diamagnetic susceptibility chi(B), that in the strong-coupling lim it varies like chi(B) approximately ((g)T)-1, and is suppressed by a f actor 0.2 g compared to the weak-coupling limit. The enhanced density of states and the suppression Of chi(B) both imply that Bose condensat ion is suppressed by the fluctuating gauge field. At lower temperature s the retracing path approximation breaks down, and one has to do a se lf-consistent calculation to determine chi(B). A numerical calculation shows that below T(BE) approximately 0.08 T(BE)0 the susceptibility c hi(B)SC diverges exponentially.