Sommerfeld enhancement from unparticle exchange for dark matter annihilation

We investigate the implication of unparticle exchange for the possible Sommerfeld enhancement in dark matter annihilation process. Assuming the unparticle exchange during WIMP collision, we solve the Schrödinger equation for the effective potential, and find that the Sommerfeld enhancement factor is dictated by the scale dimension of unparticle as 1/v3−2dU. Numerically the Sommerfeld enhancement could be O(10-103).