Production of K- p and K+ (p)over-bar bound states in pp collisions and interpretation of the Λ (1405) resonance

We study the production of charged particles (K+, K-, p, and (p) over bar) in proton-proton (pp) collisions at root s = 0.9 TeV within the PACIAE model whose parameters we fix by comparing the yield of charged particles with experimental data from ALICE. We analyze the production of K- p and K+ (p) over bar bound states with the PACIAE+DCPC model. Results of our work indicate that in pp collisions at root s = 0.9 TeV the Lambda(1405) and its antiparticle may be produced at almost the same rate if the Lambda(1405) is a K- p bound state formed during the hadron rescattering period. The combined yield of K- p and K+ (p) over bar bound states is found to be of the order of 10(-3), but the experimental results indicate that the combined yield of Lambda(1405) + (Lambda) over bar (1405) is of the order of 10(-2) if Lambda(1405) is a standard three-quark baryon. Since there are no experimental data available on this observable at present, our work may provide a guide for future experiments.