Single Spin Asymmetry of Vector Meson Production as a Probe of Asymmetry   of Parton Scattering
  Azimuthal asymmetry of vector-meson production in single-transversely polarized proton-proton collisions ($p\up p$) is calculated in the string model of particle production. The asymmetry is generated only during fragmentation of a high-energy quark into hadrons. The obtained asymmetry of the $\rho^\pm$ is opposite in sign to that of $\pi^\pm$ mesons. On the other hand, an asymmetry appearing during parton scattering would contribute with the same sign to that of vector and pseudoscalar mesons. Thus, a combined measurement of both can be used to estimate the contribution to the asymmetry from parton scattering. 
J. Czyzewski