Inclusive double-helicity asymmetries in neutral-pion and eta-meson production in $\vec{p}+\vec{p}$ collisions at $\sqrt{s}=200$ GeV

The collaboration
Phys.Rev.D 90 (2014) 012007, 2014.

Abstract (data abstract)
BNL-RHIC. Results are presented from data recorded in 2009 by the PHENIX experiment at the Relativistic Heavy Ion Collider for the double-longitudinal spin asymmetry, ASYM(LL), for PI0 and ETA production in sqrt(s) = 200 GeV polarized pp collisions. Comparison of the PI0 results with different theory expectations based on fits of other published data showed a preference for small positive values of gluon polarization, DELTA(G), in the proton in the probed Bjorken x, XB, range. The effect of adding the new 2009 PI0 data to a recent global analysis of polarized scattering data is given.