We consider the problem of cotangent bundle reduction for non free group
actions at zero momentum. We show that in this context the symplectic
stratification obtained by Sjamaar and Lerman refines in two ways: (i) each
symplectic stratum admits a stratification which we call the secondary
stratification with two distinct types of pieces, one of which is open and
dense and symplectomorphic to a cotangent bundle; (ii) the reduced space at
zero momentum admits a finer stratification than the symplectic one into pieces
that are coisotropic in their respective symplectic strata.
@article{0310437,
author = {Perlmutter, Matthew and Rodriguez-Olmos, Miguel and Sousa-Dias, M. Esmeralda},
title = {On the geometry of reduced cotangent bundles at zero momentum},
journal = {arXiv},
volume = {2003},
number = {0},
year = {2003},
language = {en},
url = {http://dml.mathdoc.fr/item/0310437}
}
Perlmutter, Matthew; Rodriguez-Olmos, Miguel; Sousa-Dias, M. Esmeralda. On the geometry of reduced cotangent bundles at zero momentum. arXiv, Tome 2003 (2003) no. 0, . http://gdmltest.u-ga.fr/item/0310437/