Higgs production at RHIC and the positivity of the gluon helicity distribution

Abstract

We show that the negative polarized gluon distribution $\hat{I}”g$ found in a recent global next-to-leading order QCD analysis of the nucleon helicity structure is incompatible with the fundamental requirement that physical cross-sections must not be negative. Specifically, we show that the fact that this polarized gluon strongly violates the positivity condition $|\hat{I}”g|\le g$ in terms of the unpolarized gluon distribution $g$ leads to negative cross-sections for Higgs boson production at RHIC as a physical process, implying that this negative $\hat{I}”g$ is unphysical.

8 pages, 2 figures, final published version