Naslov
Exclusive J/psi photoproduction off protons in ultraperipheral p-Pb collisions at root s(NN)=5.02 TeV

Autori
Abelev, B. ... ; Antičić, Tome ; ... ; Gotovac, Sven ; ... ; Mudnić, Eugen ; ... ; Planinić, Mirko ; ... ; Poljak, Nikola ; ... ; Simatović, Goran ; ... : Šuša, Tatjana ; ... ; Vicković, Linda ; ... ; Zyzak, M.

Izvornik
Physical Review Letters (0031-9007) 113 (2014), 23; 232504-1

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
J/Psi; pPb; ALICE

Sažetak
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.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

Napomena
The ALICE Collaboration.

POVEZANOST RADA