Spin correlation and discrete symmetry in spinor Bose-Einstein condensates- art. no. 08040

We study spin correlations in Bose-Einstein condensates of spin I bosons wi th scatterings dominated by a total spin equal 2 channel. We show that the low energy spin dynamics in the system can be mapped into an o(n) nonlinear sigma model. n = 3 at the zero magnetic field limit and n = 2 in the prese nce of weak magnetic fields. In an ordered phase, the ground state has a di screte Z(2) symmetry and is degenerate under the group [U(1) X Sn-1]/Z(2). We explore consequences of the discrete symmetry and propose some measureme nts to probe it.