How Much of the Nucleon Spin is Carried by Glue?

Abstract

We estimate in the QCD sum rule approach the amount of the nucleon spin carried by the gluon angular momentum: the sum of the gluon spin and orbital angular momenta. The result indicates that gluons contribute at least one half of the nucleon spin at scale of 1 GeV^2.

Comments: replaced with a couple of reference added and spell-checked