We interpret recently measured collisional frequency shifts in a cesium atomic fountain using coupled-channel theory and a simple picture of hyperfine-coupled long-range molecular states. We predict the existence of Cs2 singlet and triplet states very close to threshold with an associated strong influence on ultracold collisions and large negative values for the Cs+Cs scattering lengths. Our results are important for future precision experiments using Cs fountains, and may also have important consequences for attempts to realize a Bose condensate in an ultracold atomic Cs vapor.
All Science Journal Classification (ASJC) codes
- Atomic and Molecular Physics, and Optics