title: Breakup of shearless meanders and "outer" tori in the standard nontwist map.
abstract: The breakup of shearless invariant tori with winding number omega=(11+gamma)(12+gamma) (in continued fraction representation) of the standard nontwist map is studied numerically using Greene's residue criterion. Tori of this winding number can assume the shape of meanders [folded-over invariant tori which are not graphs over the x axis in (x,y) phase space], whose breakup is the first point of focus here. Secondly, multiple shearless orbits of this winding number can exist, leading to a new type of breakup scenario. Results are discussed within the framework of the renormalization group for area-preserving maps. Regularity of the critical tori is also investigated.
authors.affiliation: Department of Physics and Institute for Fusion Studies, The University of Texas at Austin, Austin, Texas 78712, USA.
authors.forename: K
authors.initials: K
authors.lastname: Fuchss
authors.forename: A
authors.initials: A
authors.lastname: Wurm
authors.forename: A
authors.initials: A
authors.lastname: Apte
authors.forename: P J
authors.initials: PJ
authors.lastname: Morrison