Recent STAR Results from Charged Pion Production in Polarized pp Collisions at $\sqrt{s}=200GeV$ at RHIC

Abstract

The STAR experiment at RHIC measures the longitudinal double-spin asymmetry $A_{LL}$ for a variety of final states in collisions of longitudinally polarized protons to constrain the polarized gluon distribution in the proton. Asymmetries for mid-rapidity charged pion production benefit from large cross-sections and the excellent tracking and particle identification capabilities of the STAR Time Projection Chamber. This contribution presents a measurement of the ratio of cross sections for inclusive ${\pi }^{-}$ and ${\pi }^{+}$ production using data collected in 2005, as well as a new measurement of $A_{LL}$ for charged pions opposite a jet obtained from the 2006 RHIC run.

arXiv comment4 pages, 2 figures, contribution to the Proceedings of the 18th International Symposium on Spin Physics (SPIN 2008), Charlottesville, VA, USA October 6-11, 2008

References in corpus (1)

• Identified hadron production at high transverse momenta in p+p collisions at sqrt(NN) = 200 GeV in STAR