  High order calculation at semi-hard scale is very important, but a
satisfactory calculation framework is still missing. We propose a systematic
method to regularize rapidity divergences in the CGC factorization, which makes
higher order calculation rigorous and straight forward. By applying this method
to single hadron production in pA collision, we find the kinematic constraint
effect introduced by hand in previous works comes out automatically, but with
different values. The difference is crucial for our next-to-leading order (NLO)
result to have a smaller theoretical uncertainty comparing with LO result,
which makes high order calculation in CGC factorization to be useful. As a
byproduct, the negativity problem found in literature can also be overcome in
our framework by a proper choosing of factorization scale.
