Photoproduction of J

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• 作者：PHENIX Collaboration ; S. Afanasiev ; C. Aidala ; N.N. Ajitan ; Y. Akiba ; J. Alex ; er ; A. Al-Jamel ; K. Aoki ; L. Aphecetche ; R. Armendariz ; S.H. Aronson ; R. Averbeck ; T.C. Awes ; B. Azmoun ; V. Babintsev ; A.
• 刊名：Physics Letters B
• 出版年：2009
• 出版时间：31 August 2009
• 年：2009
• 卷：679
• 期：4
• 页码：321-329
• 全文大小：897 K

文摘

We present the first measurement of photoproduction of J/ψ and of two-photon production of high-mass e⁺e⁻ pairs in electromagnetic (or ultra-peripheral) nucleus–nucleus interactions, using Au + Au data at . The events are tagged with forward neutrons emitted following Coulomb excitation of one or both Au nuclei. The event sample consists of 28 events with m_e⁺e⁻>2 GeV/c² with zero like-sign background. The measured cross sections at midrapidity of and for m_e⁺e⁻[2.0,2.8] GeV/c² have been compared and found to be consistent with models for photoproduction of J/ψ and QED based calculations of two-photon production of e⁺e⁻ pairs.