Charmonium and e super(+) e super(-) pair photoproduction at mid-rapidity in ultra-peripheral Pb-Pb collisions at

• Published in: The European physical journal. C, Particles and fields Vol. 73; no. 11; pp. 1 - 18
• Main Authors: Abbas, E, Abelev, B, Adam, J, Adamova, D, Adare, A M, Aggarwal, M M, Aglieri Rinella, G, Agnello, M, Agocs, A G, Agostinelli, A, Ahammed, Z, Ahmad, N, Ahmad Masoodi, A, Ahmed, I, Ahn, SA, Ahn, SU, Aimo, I, Ajaz, M, Akindinov, A, Aleksandrov, D, Alessandro, B, Alexandre, D, Alici, A, Alkin, A, Almaraz Avina, E, Alme, J, Alt, T, Altini, V, Altinpinar, S, Altsybeev, I, Andrei, C, Andronic, A, Anguelov, V, Anielski, J, Anson, C, AntiAeic, T, Antinori, F, Antonioli, P, Aphecetche, L, Appelshaeuser, H, Arbor, N, Arcelli, S, Arend, A, Armesto, N, Arnaldi, R, Aronsson, T, Arsene, I C, Arslandok, M, Asryan, A, Augustinus, A, et. al
• Format: Journal Article
• Language: English
• Published: 01.11.2013
• Subjects: Coherence; Collisions; Cooperation; Cross sections; Lead (metal); Luminosity; Photoproduction
• ISSN: 1434-6044; 1434-6052
• DOI: 10.1140/epjc/s10052-013-2617-1

(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image).The ALICE Collaboration at the LHC has measured the J/ psi and psi ' photoproduction at mid-rapidity in ultra-peripheral Pb-Pb collisions at ... The charmonium is identified via its leptonic decay for events where the hadronic activity is required to be minimal. The analysis is based on an event sample corresponding to an integrated luminosity of about 23 mu b super(-1). The cross section for coherent and incoherent J/ psi production in the rapidity interval -0.9<y<0.9, are ... and ..., respectively. The results are compared to theoretical models for J/ psi production and the coherent cross section is found to be in good agreement with those models incorporating moderate nuclear gluon shadowing at Bjorken-x around 10 super(-3), such as EPS09 parametrization. In addition the cross section for the process gamma gamma arrow right e super(+) e super(-) has been measured and found to be in agreement with models implementing QED at leading order.