Single spin asymmetry measurements ([Formula: see text]) of the azimuthal distribution of charged pions inside jets produced in transversely polarized proton collisions are sensitive to the transversity distribution and the Collins fragmentation function. The STAR Detector at the Relativistic Heavy Ion Collider is well suited for these types of measurements as it is capable of full jet reconstruction and charged pion identification in the mid-rapidity region ([Formula: see text][Formula: see text][Formula: see text][Formula: see text]). We report here the first observation of Collins [Formula: see text] asymmetries in [Formula: see text] GeV [Formula: see text] collisions.
Transverse single-spin asymmetries of midrapidity
π0
and
η
mesons in polarized
p+p
collisions at
s=200 GeV
