(Lambda)over-bar production and (Lambda)over-bar/(p)over-bar ratio in relativistic heavy ion collisions

The <(Lambda)over bar> multiplicity and <(Lambda)over bar>/(p) over bar rat io are studied by hadron transportation-string fragmentation model in relat ivistic heavy ion collisions. Firstly, the dependence of <(Lambda)over bar> multiplicity and <(Lambda)over bar>/(p) over bar ratio on the system size and the collision centrality is studied. It shows that the <(Lambda)over ba r> and (p) over bar multiplicities go up as the increase of system size and the increase of collision centrality. However, their ratio keeps almost a constant. The effect of <(Lambda)over bar> annihilation cross section to <( Lambda)over bar> multiplicity and <(Lambda)over bar>/(p) over bar ratio is also studied. It is found that this effect is weak: <(Lambda)over bar> mult iplicity and <(Lambda)over bar>/(p) over bar ratio have a little amount of increase by the decrease of <(Lambda)over bar> annihilation cross section. Even the cross section is down to zero, <(Lambda)over bar>/(p) over bar rat io is only 1.2 in 200A GeV AuAu head on collision. The <(Lambda)over bar>/( p) over bar ratio is obtained to be 0.28 in pp collision, lying in the rang e of experimental data: 0.2-0.3. It is also obtained that the ratio in AA c ollisions is 3-5 times of that in pp collision.