ANOMALOUS SPECTRAL STATISTICS IN A SYMMETRICAL BILLIARD

It is a common assumption that time reversal invariance or some other antiunitary symmetry for a classically chaotic system implies GOE-type spectral fluctuations for the corresponding quantum system. Based on previous work on structural invariance, we show that a time-reversal i nvariant system for certain point symmetries displays the GUE statisti cs typical of systems with broken time-reversal symmetry; specifically a billiard having only threefold symmetry shows this unexpected behav iour.