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Forward and midrapidity like-particle ratios from p + p collisions at s = 200 GeV

2004; Elsevier BV; Volume: 607; Issue: 1-2 Linguagem: Inglês

10.1016/j.physletb.2004.12.064

1873-2445

I. G. Bearden, D. Beavis, C. Beşliu, B. Budick, H. Bøggild, C. Chasman, C. H. Christensen, P. Christiansen, J. Cibor, R. Debbe, E. Enger, J. J. Gaardhøje, M. Germinario, K. Hagel, Anders Holm, A.K. Holme, H. Ito, Emil Jakobsen, A. Jipa, F. Jundt, J. I. Jørdre, C.E. Jørgensen, R. Karabowicz, T. Keutgen, E. J. Kim, T. Kozik, T.M. Larsen, J.H. Lee, Y.K. Lee, G. Løvhøiden, Z. Majka, A. Makeev, M. Mikelsen, M.J. Murray, J. B. Natowitz, B. S. Nielsen, J. Norris, K. Olchanski, D. Ouerdane, R. Płaneta, F. Rami, C. Ristea, D. Röhrich, B. H. Samset, D. Sandberg, S. J. Sanders, R.A. Scheetz, P. Staszel, T. S. Tveter, F. Videbæk, R. Wada, A. Wieloch, Z. Yin, I. S. Zgură,

Particle physics theoretical and experimental studies

We present a measurement of pi-\pi+, K-/K+ and pbar/p from p+p collisions at sqrt(s) = 20 0GeV over the rapidity range 0<y<3.4. For pT < 2.0 GeV/c we see no significant transverse momentum dependence of the ratios. All three ratios are independent of rapidity for y ~< 1.5 and then steadily decline from y ~ 1.5 to y ~ 3. The pi-\pi+ ratio is below unity for y > 2.0. The pbar/p ratio is very similar for p+p and 20% central Au+Au collisions at all rapidities. In the fragmentation region the three ratios seem to be independent of beam energy when viewed from the rest frame of one of the protons. Theoretical models based on quark-diquark breaking mechanisms overestimate the pbar/p ratio up to y ~< 3. Including additional mechanisms for baryon number transport such as baryon junctions leads to a better description of the data.