ELECTROMAGNETIC RESPONSE OF THE GAUGE-FIELD MODEL

We calculated the polarization function of the gauge field model at fi nite temperature. The effect of the gauge field was considered io the order of O-0(N) in the convention of a 1/N expansion. We found signifi cant cancellation among Feynman diagrams. As a result, the real part o f conductivity has the following behavior: In the low frequency region it is proportional to 1/omega(2), similar to that in the Drude model and in the infrared frequency region there is contribution from an exc iting-gauge field and particle-hole pair. This makes Re sigma(omega) d ecrease much slower than that in the Drude model. Another important co nsequence of the cancellation is that Re sigma(omega) in the low-frequ ency region is temperature sensitive but not so when the frequency app roaches the Fermi energy.