The Spin Alignment of Vector Mesons in High Energy pp Collisions

The spin alignment of vector meson produced in high energy reactions is determined by the spin-dependent fragmentation function $D_{1LL} (z,\mu_f)$ that is shown to be independent of the polarization of the fragmenting quark. In this paper, we extract the spin-dependent fragmentation function $D_{1LL} (z,\mu_f)$ from data on the spin alignment of $K^{*0}$ in $e^+e^-$ annihilation at LEP in two different scenarios and apply them to make predictions in $pp$ collisions. We make detailed analysis of contributions from different sub-processes and show that the spin alignment should be quite significant also in high energy $pp$ collisions.