A.Apte, A.Wurm, P.J.Morrison
Renormalization and destruction of $1/\gamma^2$ tori in the 
 standard nontwist map
(1290K, postscript)

ABSTRACT.  Extending the work of del-Castillo-Negrete, Greene, and Morrison, 
Physica D {\bf 91}, 1 (1996) and {\bf 100}, 311 (1997) on the 
standard nontwist map, the breakup of an invariant torus 
with winding number equal to the inverse golden mean squared is 
studied. Improved numerical techniques provide the greater accuracy 
that is needed for this case. The new results are interpreted within 
the renormalization group framework by constructing a renormalization 
operator on the space of commuting map pairs, and by studying the 
fixed points of the so constructed operator.