Charmonium and e(+)e(-) pair photoproduction at mid-rapidity in ultra-peripheral Pb-Pb collisions at root s(NN)=2.76 TeV
ALICE Collaboration (ukupan broj autora: 984)
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The ALICE Collaboration at the LHC has measured the J/psi and psi photoproduction at mid-rapidity in ultra-peripheral Pb-Pb collisions at root s(NN) = 2.76 TeV. 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(-1). The cross section for coherent and incoherent J/psi production in the rapidity interval -0.9 LT y LT 0.9, are d sigma(coh)(J/psi)/dy = 2.38(-0.24)(+0.34)(sta + sys) mb and d sigma(inc)(J/psi)/dy = 0.98(-0.17)(+0.19)(sta + sys) mb 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(-3), such as EPS09 parametrization. In addition the cross section for the process gamma gamma - GT e(+)e(-) has been measured and found to be in a...greement with models implementing QED at leading order.
Izvor:European Physical Journal C. Particles and Fields, 2013, 73, 11
- State Committee of Science, World Federation of Scientists (WFS), Swiss Fonds Kidagan, Armenia, Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq), Financiadora de Estudos e Projetos (FINEP), Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP), National Natural Science Foundation of China (NSFC), Chinese Ministry of Education (CMOE), Ministry of Science and Technology of China (MSTC), Ministry of Education and Youth of the Czech Republic, Danish Natural Science Research Council, Carlsberg Foundation, Danish National Research Foundation, The European Research Council under European Community, Helsinki Institute of Physics, Academy of Finland, French CNRS-IN2P3, Region Pays de Loire, Region Alsace, Region Auvergne, CEA, France, German BMBF, Helmholtz Association, General Secretariat for Research and Technology, Ministry of Development, Greece, Hungarian OTKA, National Office for Research and Technology (NKTH), Department of Atomic Energy and Department of Science and Technology of the Government of India, Istituto Nazionale di Fisica Nucleare (INFN), Centro Fermi-Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi, Italy, MEXT, Japan, Joint Institute for Nuclear Research, Dubna, National Research Foundation of Korea (NRF), CONACYT, DGAPA, Mexico, ALFA-EC, EPLANET Program (European Particle Physics Latin American Network), Stichting voor Fundamenteel Onderzoek der Materie (FOM), Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO), Netherlands, Research Council of Norway (NFR), Polish Ministry of Science and Higher Education, National Authority for Scientific Research-NASR (Autoritatea National a pentru Cercetare Stiintifica-ANCS), Ministry of Education and Science of Russian Federation, Russian Academy of Sciences, Russian Federal Agency of Atomic Energy, Russian Federal Agency for Science and Innovations, The Russian Foundation for Basic Research, Ministry of Education of Slovakia, Department of Science and Technology, South Africa, CIEMAT, EELA, Ministerio de Economia y Competitividad (MINECO) of Spain, Xunta de Galicia (Conseller a de Educacion), CEADEN, Cubaenergia, Cuba, IAEA (International Atomic Energy Agency), Swedish Research Council (VR), Knut and Alice Wallenberg Foundation (KAW), Ukraine Ministry of Education and Science, United Kingdom Science and Technology Facilities Council (STFC), The United States Department of Energy, United States National Science Foundation, State of Texas, State of Ohio