Rapidity dependence of the proton-to-pion ratio in Au + Au and p + p collisions at sqrt(sN N) = 62.4 and 200 GeV

I. G. Arsene, I. G. Bearden, D. Beavis, S. Bekele, C. Besliu, B. Budick, H. Bøggild, C. Chasman, C. H. Christensen, P. Christiansen, H. H. Dalsgaard, R. Debbe, J. J. Gaardhøje, K. Hagel, H. Ito, A. Jipa, E. B. Johnson, C. E. Jørgensen, R. Karabowicz, N. KatryńskaE. J. Kim, T. M. Larsen, J. H. Lee, G. Løvhøiden, Z. Majka, A. Marcinek, M. J. Murray, J. Natowitz, B. S. Nielsen, C. Nygaard, D. Pal, A. Oviller, R. Płaneta, F. Rami, C. Ristea, O. Ristea, D. Röhrich, S. J. Sanders, P. Staszel, T. S. Tveter, F. Videbæk, R. Wada, H. Yang, Z. Yin, I. S. Zgura

    Research output: Contribution to journalArticlepeer-review


    The proton-to-pion ratios measured in the BRAHMS experiment for Au + Au and p + p collisions at sqrt(sN N) = 62.4 and 200 GeV are presented as a function of transverse momentum and collision centrality at selected pseudorapidities in the range of 0-3.8. A strong pseudorapidity dependence of these ratios is observed. We also compare the magnitude and pT-dependence of the p / π+ ratios measured in Au + Au collisions at sqrt(sN N) = 200 GeV and η ≈ 2.2 with the same ratio measured at sqrt(sN N) = 62.4 GeV and η = 0. The great similarity found between these ratios throughout the whole pT range (up to 2.2 GeV / c) is consistent with particle ratios in A + A collisions being described with grand-canonical distributions characterized by the baryo-chemical potential μB. At the collision energy of 62.4 GeV, we have observed a unique point in pseudorapidity, η = 3.2, where the p / π+ ratio is independent of the collision system size in a wide pT-range of 0.3 ≤ pT ≤ 1.8 GeV / c.

    Original languageEnglish (US)
    Pages (from-to)22-27
    Number of pages6
    JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
    Issue number1
    StatePublished - Feb 1 2010


    • Forward rapidity
    • Hadronization
    • Heavy ion collision
    • Particle ratios

    ASJC Scopus subject areas

    • Nuclear and High Energy Physics


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