TY  - JOUR
AB  - <p>We present the first measurement at the LHC of exclusive J/ψ photoproduction off protons, in ultraperipheral proton-lead collisions at √sNN=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 σ(γ+p→J/ψ+p) are 33.2±2.2(stat)±3.2(syst)±0.7(theor)  nb in p−Pb and 284±36(stat)+27−32(syst)±26(theor)  nb in Pb−p collisions. We measure this process up to about 700 GeV in the γp 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/ψ photoproduction cross section in γp energies from about 20 to 700 GeV, or equivalently, from Bjorken x scaling variable between ∼2×10−2 and ∼2×10−5, thus indicating no significant change in the gluon density behavior of the proton between HERA and LHC energies.</p>...
AU  - Abelev, Betty
AU  - Adam, Jaroslav
AU  - Adamová, Dagmar
AU  - Aggarwal, Madan M
AU  - Aglieri Rinella, Gianluca
AU  - Agnello, Michelangelo
AU  - Agostinelli, Andrea
AU  - Agrawal, Nikita
AU  - Ahmad, Nazeer
AU  - Ahn, Sang Un
AU  - Alme, Johan
AU  - Erdal, Hege Austrheim
AU  - Helstrup, Håvard
AU  - Hetland, Kristin Fanebust
AU  - Kileng, Bjarte
AU  - Altinpinar, Sedat
AU  - Djuvsland, Øystein
DA  - 2014
DO  - 10.1103/physrevlett.113.232504
J2  - Physical review letters
KW  - Physics
LA  - eng
PB  - American Physical Society
PY  - 2014
SN  - 1079-7114
SN  - 0031-9007
T2  - Physical review letters
TI  - Exclusive J /ψ photoproduction off protons in ultraperipheral p-Pb collisions at √sNN = 5.02TeV
UR  - http://hdl.handle.net/1956/9883
Y2  - 2021-03-04T04:08:25+01:00
ER  -