TITLE:

The first measurement of the spin dependent azimuthial asymmetry of inclusive charged pions in mid-rapidity jets in transversly polarized proton collisions at \sqrt{s}=200 GeV.

ABSTRACT:

The spin dependent azimuthal asymmety of inclusive charged pions inside fully reconstructed jets at mid-rapidity has been measured for the first time in transversly polarized proton collisions at \sqrt{s}=200 GeV.  The data were taken with the STAR Detector and sampled 1 pb-1 of proton-proton collisions with an average transverse beam polarization of 58%.  The jets span pseudorapidities $ 0.8<eta<0.8 $ and the charged pions cover $ 0.1 < z < 0.7 $ and $ 0.5 < j_T < 0.3 $.  The z and $j_T$ averaged $\pi^+$($\pi^-$) asymmetries  were found to be  -0.0051+/-0.0022+/-0.02 (0.0055+/-0.0023+/-0.02).  The  asymmetry dependence on z and $j_T$ is discussed.