Speaker
Description
The spin polarization of $\Lambda$ hyperon in low-energy Au-Au collision can be generated from the nonlocal nucleon-nucleon scattering. The Lagrangian of baryon-meson interaction is obtained from the chiral perturbation theory, and we introduce a wave packet for the incoming nucleons to describe the nonlocal collision. We evaluate the spin dependent cross sections with the approximations that the width of the wave packet is small and the collision energy is close to the threshold of $\Lambda$ production. The $\Lambda$ polarization emerges in peripheral collisions as a consequence of spin-orbit coupling. Our result gives a spin polarization of several percent, which is consistent with the experimental data of Au-Au collision at 3 GeV from STAR collaboration.
