Tuning the scattering length on the ground triplet state of Cs_2

We develop two schemes for tuning the scattering length on the ground triplet state of Cs_2. First, an absolute value of the triplet scattering length of ^{133}Cs_2 is determined using the experimental data (Fioretti et al, Eur.Phys.J. 5, 389 (1999)). We demonstrate that the large scattering length can be made small and positive by coupling of the ^3\Sigma_u^+ (6S + 6S) potential to the ^3\Pi_g state by strong off-resonant radiation. A weaker laser field coupling the ^3\Sigma_u^+ (6S + 6S) continuum to the lowest bound level of the excited ^3\Sigma_g^+ (6S + 6P) also leads to a small positive scattering length. In addition, the scattering length of the ^{135}Cs isotope is found to be positive. The method used solves the Schroedinger equation for two electronic states coupled by an electromagnetic field with approximations employed. The scattering length is determined from calculated continuum wavefunctions of low energy.