Sensitivity of ultracold-atom scattering experiments to variation of the fine-structure constant

We present numerical calculations for cesium and mercury to estimate the sensitivity of the scattering length to the variation of the fine-structure constant a. The method used follows the ideas of Chin and Flambaum [Phys. Rev. Lett. 96, 230801 (2006)], where the sensitivity to the variation of the electron-to-proton mass ratio beta was considered. We demonstrate that for heavy systems, the sensitivity to the variation of a is of the same order of magnitude as to the variation of beta. Near narrow Feshbach resonances, the enhancement of the sensitivity may exceed nine orders of magnitude.