Exclusive J/psi Photoproduction off Protons in Ultraperipheral p-Pb Collisions at root s(NN)=5.02 TeV
ALICE Collaboration (ukupan broj autora: 951)
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We present the first measurement at the LHC of exclusive J/psi photoproduction off protons, in ultraperipheral proton-lead collisions at root s(NN) = 5.02 TeV. Events are selected with a dimuon pair produced either in the rapidity interval, in the laboratory frame, 2.5 LT y LT 4 (p-Pb) or -3.6 LT y LT -2.6 (Pb-p), and no other particles observed in the ALICE acceptance. The measured cross sections sigma(gamma + p - GT J/psi + p) are 33.2 +/- 2.2(stat) +/- 3.2(syst) +/- 0.7(theor) nb in p-Pb and 284 +/- 36(stat)(-32)(+27)(syst) +/- 26(theor) nb in Pb-p collisions. We measure this process up to about 700 GeV in the gamma p center of mass, which is a factor of two larger than the highest energy studied at HERA. The data are consistent with a power law dependence of the J/psi photoproduction cross section in gamma p energies from about 20 to 700 GeV, or equivalently, from Bjorken x scaling variable between similar to 2 x 10(-2) and similar to 2 x 10(-5), thus indicating no significant chan...ge in the gluon density behavior of the proton between HERA and LHC energies.
Извор:Physical Review Letters, 2014, 113, 23
- Grid centres, Worldwide LHC Computing Grid (WLCG) collaboration, 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, European Research Council under the European Communitys Seventh Framework Programme, Helsinki Institute of Physics and the 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, 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, 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 Science Centre, Poland, Ministry of National Education/Institute for Atomic Physics, CNCS-UEFISCDI Romania, 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, 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 (Conselleria 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), United States Department of Energy, United States National Science Foundation, State of Texas, State of Ohio, Ministry of Science, Education and Sports of Croatia and Unity through Knowledge Fund, Croatia