Transverse-energy distributions at midrapidity in p+p, d+Au, and Au+Au collisions at √sNN=62.4-200 GeV and implications for particle-production models

Adler, S. S. and Afanasiev, S. and Aidala, C. and Ajitanand, N. N. and Akiba, Y. and Al-Jamel, A. and Alexander, J. and Aoki, K. and Aphecetche, L. and Armendariz, R. and Aronson, S. H. and Averbeck, R. and Awes, T. C. and Azmoun, B. and Babintsev, V. and Baldisseri, A. and Barish, K. N. and Barnes, P. D. and Bassalleck, B. and Bathe, S. and Batsouli, S. and Baublis, V. and Bauer, F. and Bazilevsky, A. and Belikov, S. and Bennett, R. and Berdnikov, Y. and Bjorndal, M. T. and Boissevain, J. G. and Borel, H. and Csanád, Máté and Csörgő, Tamás and Dávid, Gábor and Hidas, Pál and Kiss, Ádám and Ster, András and Sziklai, János István and Tarján, Péter and Vértesi, Róbert and Veszprémi, Viktor and Zimányi, József (2014) Transverse-energy distributions at midrapidity in p+p, d+Au, and Au+Au collisions at √sNN=62.4-200 GeV and implications for particle-production models. PHYSICAL REVIEW C, 89 (4). ISSN 2469-9985

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Abstract

Measurements of the midrapidity transverse energy distribution, dET /dη, are presented for p+p, d+Au, and Au+Au collisions at √sN N = 200 GeV and additionally for Au+Au collisions at √sN N = 62.4 and 130 GeV. The dET /dη distributions are first compared with the number of nucleon participants Npart, number of binary collisions Ncoll , and number of constituent-quark participants Nqp calculated from a Glauber model based on the nuclear geometry. For Au+Au, 〈dET /dη〉/Npart increases with Npart, while 〈dET /dη〉/Nqp is approximately constant for all three energies. This indicates that the two component ansatz, dET /dη ∝ (1 − x)Npart/2 + xNcoll, which has been used to represent ET distributions, is simply a proxy for Nqp, and that the Ncoll term does not represent a hard-scattering component in ET distributions. The dET /dη distributions of Au+Au and d+Au are then calculated from the measured p+p ET distribution using two models that both reproduce the Au+Au data. However, while the number-of-constituent-quark-participant model agrees well with the d+Au data, the additive-quark model does not.

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