  We derive a factorization theorem for the Higgs boson transverse momentum
(p_T) and rapidity (Y) distributions at hadron colliders, using the Soft
Collinear Effective Theory (SCET), for m_h>> p_T>> \Lambda_{QCD} where m_h
denotes the Higgs mass. In addition to the factorization of the various scales
involved, the perturbative physics at the p_T scale is further factorized into
two collinear impact-parameter Beam Functions (iBFs) and an inverse Soft
Function (iSF). These newly defined functions are of a universal nature for the
study of differential distributions at hadron colliders. The additional
factorization of the p_T-scale physics simplifies the implementation of higher
order radiative corrections in \alpha_s(p_T). We derive formulas for
factorization in both momentum and impact parameter space and discuss the
relationship between them. Large logarithms of the relevant scales in the
problem are summed using the renormalization group equations of the effective
theories. Power corrections to the factorization theorem in p_T/m_h and
\Lambda_{QCD}/p_T can be systematically derived. We perform multiple
consistency checks on our factorization theorem including a comparison with
known fixed order QCD results. We compare the SCET factorization theorem with
the Collins-Soper-Sterman approach to low-p_T resummation.
