Statistics of holons and spinons in the t-J model

We study the statistics of holons and spinons in the 2-dimensional t-J model of high-Tc superconductors by applying the gauge theory of separation phenomena that we have developed recently. This study is motivated by the observation that, near the half filling, the spin degrees of freedom of the t-J model are correctly described by bosonic variables as in the slave-fermion representation, while, at intermediate hole concentrations, spinons behave as fermions as in the slave boson representation, sup-porting a large Fermi surface. In the previous papers, we studied the charge-spin separation (CSS) in high-Tc superconductors and the particle-flux separation (PFS) in the fractional quantum Hall effect (FQHE), and showed that both of them are understood as phase transitions of certain gauge theories into their deconfinement phases, where the gauge fields are nothing but the phases of mean fields sitting on links. For example, the CSS occurs when the dynamics of the gauge field that glues a holon and a spinon is relaized in the deconfinement phase; holons and spinons appear as quasiexcitations. In the present paper, we start with the slave-boson representation of the t-J model, in which an electron is a composite of a fermionic spinon