Within the intermediate-coupling theory, the quasiparticle weight $Z$ of one hole injected in the undoped antiferromagnetic ground state is studied. We find that, for the hole located at the quasiparticle band minimun with momentum ${ \bf k}_0 = (\pm \frac{ \pi}{ 2}, \pm \frac{ \pi}{ 2})$, $Z$ is finite. By comparing the results obtained by the self-consistent Born approximation, we show that the intermediate-coupling theory for $Z$ is appropriate only when $J/t \stackrel{ >}{ \sim} 1.6$. Finally, the reason why this approach fails in the small-$J$ case will also be clarified.
Categories: cond-mat