Precision Measurement of the Longitudinal Double-spin Asymmetry for   Inclusive Jet Production in Polarized Proton Collisions at $\sqrt{s}=200$ GeV
  We report a new high-precision measurement of the mid-rapidity inclusive jet longitudinal double-spin asymmetry, $A_{LL}$, in polarized $pp$ collisions at center-of-mass energy $\sqrt{s}=200$ GeV. The STAR data place stringent constraints on polarized parton distribution functions extracted at next-to-leading order from global analyses of inclusive deep inelastic scattering (DIS), semi-inclusive DIS, and RHIC $pp$ data. The measured asymmetries provide evidence for positive gluon polarization in the Bjorken-$x$ region $x>0.05$. 
STAR Collaboration: L. Adamczyk, J. K. Adkins, G. Agakishiev, M. M.   Aggarwal, Z. Ahammed, I. Alekseev, J. Alford, C. D. An...
hep-ex nucl-ex