Positivity of NLO Spin-Dependent Parton Distributions

Bourrely, C.; Leader, E.; Teryaev, O. V.

Positivity of NLO Spin-Dependent Parton Distributions

Authors

Bourrely, C.

Leader, E.

Teryaev, O. V.

Description

We discuss the positivity of the hadron density matrix in QCD. This basic property is shown to be preserved by QCD evolution, provided the relation $|ΔP_{ij}(z)| \leq P_{ij}$ is valid for all kernels for $z < 1$, and the usual "+" prescription is used. We comment on the positivity restrictions for the choice of the NLO factorization scheme for the evolution of the spin-dependent parton distributions.
6 pages, LateX, 1 figure