09134nas a2200205 4500008004100000245007700041210006900118260001500187300001000202490000600212520852300218100001708741700002208758700001908780700002308799700001808822700001908840700002208859856004708881 2016 eng d00aMultiple scattering dynamics of fermions at an isolated p-wave resonance0 aMultiple scattering dynamics of fermions at an isolated pwave re c2016/07/11 a120690 v73 a

The wavefunction for indistinguishable fermions is anti-symmetric under particle exchange, which directly leads to the Pauli exclusion principle, and hence underlies the structure of atoms and the properties of almost all materials. In the dynamics of collisions between two indistinguishable fermions this requirement strictly prohibits scattering into 90 degree angles. Here we experimentally investigate the collisions of ultracold clouds fermionic 40K atoms by directly measuring scattering distributions. With increasing collision energy we identify the Wigner threshold for p-wave scattering with its tell-tale dumb-bell shape and no 90 yield. Above this threshold effects of multiple scattering become manifest as deviations from the underlying binary p-wave shape, adding particles either isotropically or axially. A shape resonance for 40K facilitates the separate observation of these two processes. The isotropically enhanced multiple scattering mode is a generic p-wave threshold phenomenon, while the axially enhanced mode should occur in any colliding particle system with an elastic scattering resonance.

1 aThomas, Ryan1 aRoberts, Kris, O.1 aTiesinga, Eite1 aWade, Andrew, C.J.1 aBlakie, Blair1 aDeb, Amita, B.1 aKjærgaard, Niels uhttp://www.nature.com/articles/ncomms12069