Lawrence Berkeley National Laboratory

We study the semi-inclusive hadron production in deep inelastic scattering at small-x. A transverse momentum dependent factorization is found consistent with the results calculated in the color-dipole framework in the appropriate kinematic region. The transverse momentum dependent quark distribution can be studied in this process as a probe for the small-x saturation physics. Especially, the ratio of the quark distributions as functions of transverse momentum at different x demonstrates strong dependence on the saturation scale. The Q2 dependence of the same ratio is also studied by applying the Collins-Soper-Sterman resummation method.