Collision Properties of Ultracold ${}_{}{}^{133}{}_{}{}^{}Cs$ Atoms

We present a theoretical analysis of numerous magnetically tunable Feshbach resonances measured by Chin et al. [preceding Letter, Phys. Rev. Lett. 85, 2717 (2000)] at fields of up to $25\mathrm{mT}$. This analysis provides the most accurate characterization of the collisional properties of ground state Cs atoms currently available and clearly shows, in contrast to previous work, that Bose-Einstein condensation of ${}^{133}\mathrm{Cs}$ cannot be ruled out. The $X^1{\Sigma }_g^{+}$ and $a^3{\Sigma }_u$ scattering lengths are constrained to $(280\pm 10)a_0$ and $(2400\pm 100)a_0$, respectively ( ${1a}_0=0.052\mathrm{}9177\mathrm{nm}$), and the van der Waals $C_6$ coefficient to $6890\pm 35\mathrm{a}.\mathrm{u}.\mathrm{}(1\mathrm{a}.\mathrm{u}.\mathrm{}=0.095\mathrm{}7345\times {10}^{-24\mathrm{}}\mathrm{J}̇{\mathrm{nm}}^6)$.