Exclusive J/psi Photoproduction off Protons in Ultraperipheral p-Pb Collisions at root s(NN)=5.02 TeV

0440205 - ÚJF 2015 RIV US eng J - Článek v odborném periodiku
Abelev, B. - Adam, J. - Adamová, Dagmar - Bielčík, J. - Bielčíková, Jana - Broz, M. - Čepila, J. - Ferencei, Jozef - Hladký, Jan - Křelina, M. - Křížek, Filip - Kučera, Vít - Kushpil, Svetlana - Mareš, Jiří A. - Pachr, M. - Petráček, V. - Petráň, M. - Schulc, M. - Špaček, M. - Šumbera, Michal - Vajzer, Michal - Zach, Č. - Závada, Petr … celkem 950 autorů
Exclusive J/psi Photoproduction off Protons in Ultraperipheral p-Pb Collisions at root s(NN)=5.02 TeV.
Physical Review Letters. Roč. 113, č. 23 (2014), s. 232504. ISSN 0031-9007. E-ISSN 1079-7114
Grant CEP: GA MŠMT(CZ) LG13031
Institucionální podpora: RVO:68378271 ; RVO:61389005
Klíčová slova: LHC * ALICE experiment * center of mass
Kód oboru RIV: BG - Jaderná, atomová a mol. fyzika, urychlovače; BF - Elementární částice a fyzika vys. energií (FZU-D)
Impakt faktor: 7.512, rok: 2014

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 < y < 4 (p-Pb) or -3.6 < y < -2.6 (Pb-p), and no other particles observed in the ALICE acceptance. The measured cross sections sigma(gamma + p -> 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 change in the gluon density behavior of the proton between HERA and LHC energies.
Trvalý link: http://hdl.handle.net/11104/0243370