Slave-particle studies of the electron-momentum distribution in the low-dimensionalt-Jmodel

The electron-momentum distribution function in the t-J model is studied in the framework of the slave-particle approach. Within the decoupling scheme used in gauge-field and related theories, we treat formally phase and amplitude fluctuations as well as constraints without further approximations. Our result indicates that the electron Fermi surface observed in high-resolution angle-resolved photoemission and inverse-photoemission experiments cannot be explained within this framework, and the sum rule for the physical electron is not obeyed. A correct scaling behavior of the electron-momentum distribution function near k∼${\mathit{k}}_{\mathit{F}}$ and k∼3${\mathit{k}}_{\mathit{F}}$ in one dimension can be reproduced by considering the nonlocal string fields [Z. Y. Weng et al., Phys. Rev. B 45, 7850 (1992)], but the overall momentum distribution is still not correct, at least at the mean-field level.