Directed flow of neutral strange particles at AGS

The directed flow of neutral strange particles in heavy-ion collisions at the alternating gradient synchrotron (AGS) at the Brookhaven National Laboratory is studied in the ART transport model. Using a lambda mean-field potential that is (2/3) of the nucleon potential as predicted by the constituent quark model, lambdas are found to flow with protons but with a smaller flow parameter as observed in experiments. For kaons, their repulsive potential, which is calculated from the impulse approximation using the measured kaon-nucleon scattering length, leads to a smaller antiflow than that shown in the E895 data. The implications of this discrepancy are discussed.