Here we review a method for constructing exact eigenvalues and eigenfunctions
of a many-particle quantum system, which is obtained by adding some
nonhermitian but PT invariant (i.e., combined parity and time reversal
invariant) interaction to the Calogero model. It is shown that such extended
Calogero model leads to a real spectrum obeying generalised exclusion
statistics. It is also found that the corresponding exchange statistics
parameter differs from the exclusion statistics parameter and exhibits a
`reflection symmetry' provided the strength of the PT invariant interaction
exceeds a critical value.Comment: 8 pages, Latex, Talk given at Joint APCTP-Nankai Symposium, Tianjin
(China), Oct. 200