Abstract
Rapidity-odd directed flow v(1) measurements are presented for K-+/- and K-S(0) in Au + Au collisions for root s(NN) from 3.0 to 3.9 GeV with the STAR experiment. For comparison, v(1) of pi(+/-), protons, and. from the same collisions are also discussed. The mid-rapidity v(1) slope dv(1)/dy vertical bar(y=0) for protons and. is positive in these collisions. On the other hand, v(1) slope of kaons exhibits a strong p(T) dependence: negative at p(T) < 0.6 GeV/c and positive at higher p(T). A similar p(T) dependence is also evident for the v(1) slope of charged pions. Compared to the spectator-removed calculations in Au+Au collisions at root s(NN) = 3.0-3.9 GeV, the JAM model demonstrates a pronounced shift of the v(1) slopes of mesons towards the negative direction. It suggests that the shadowing effect of the spectators plays an important role in the observed kaon anti-flow at low p(T) in the high baryon density region of non-central collisions.