Fractional statistics in some exactly solvable models with PT invariant interactions

Here we review a method for constructing exact eigenvalues and eigenfunotions 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.