Suppression of ϒ(1S) at forward rapidity in Pb–Pb collisions at √sNN = 2.76 TeV

Abelev, B. and Adam, J. and Adamová, D. and Aggarwal, M. M. and Agnello, M. and Agostinelli, A. and Agrawal, N. and Ahammed, Z. and Ahmad, N. and Ahmed, I. and Ahn, S. U. and Ahn, S. A. and Aimo, I. and Aiola, S. and Ajaz, M. and Akindinov, A. and Alam, S. N. and Aleksandrov, D. and Alessandro, B. and Alexandre, D. and Alici, A. and Alkin, A. and Alme, J. and Alt, T. and Altinpinar, S. and Altsybeev, I. and Alves, Garcia Prado C. and Andrei, C. and Andronic, A. and Anguelov, V. and Barnaföldi, Gergely Gábor and Bencédi, Gyula and Berényi, Dániel and Boldizsár, László and Dénes, Ervin and Hamar, Gergő and Kiss, Gábor and Varga-Kőfaragó, Mónika and Lévai, Péter and Molnár, Levente and Oláh, László and Pochybova, Sona (2014) Suppression of ϒ(1S) at forward rapidity in Pb–Pb collisions at √sNN = 2.76 TeV. PHYSICS LETTERS B, 738. pp. 361-372. ISSN 0370-2693

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Abstract

We report on the measurement of the inclusive ϒ(1S) production in Pb–Pb collisions at √sNN = 2.76 TeV carried out at forward rapidity (2.5 < y < 4) and down to zero transverse momentum using its μ+ μ− decay channel with the ALICE detector at the Large Hadron Collider. A strong suppression of the inclusive ϒ(1S) yield is observed with respect to pp collisions scaled by the number of independent nucleon-nucleon collisions. The nuclear modification factor, for events in the 0–90% centrality range, amounts to 0.30 ± 0.05(stat) ± 0.04(syst). The observed ϒ(1S) suppression tends to increase with the centrality of the collision and seems more pronounced than in corresponding mid-rapidity measurements. Our results are compared with model calculations, which are found to underestimate the measured suppression and fail to reproduce its rapidity dependence.

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