Bibcode
Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Brandstetter, J.; Brondolin, E.; Dragicevic, M.; Erö, J.; Flechl, M.; Friedl, M.; Frühwirth, R.; Ghete, V. M.; Hartl, C.; Hörmann, N.; Hrubec, J.; Jeitler, M.; König, A.; Krammer, M.; Krätschmer, I.; Liko, D.; Matsushita, T.; Mikulec, I.; Rabady, D.; Rad, N.; Rahbaran, B.; Rohringer, H.; Schieck, J.; Schöfbeck, R.; Strauss, J.; Treberer-Treberspurg, W.; Waltenberger, W.; Wulz, C.-E.; Mossolov, V.; Shumeiko, N.; Suarez Gonzalez, J.; Alderweireldt, S.; Cornelis, T.; De Wolf, E. A.; Janssen, X.; Knutsson, A.; Lauwers, J.; Luyckx, S.; Van De Klundert, M.; Van Haevermaet, H.; Van Mechelen, P.; Van Remortel, N.; Van Spilbeeck, A.; Abu Zeid, S.; Blekman, F.; D'Hondt, J.; Daci, N.; De Bruyn, I.; Deroover, K.; Heracleous, N.; Keaveney, J.; Lowette, S.; Moortgat, S.; Moreels, L.; Olbrechts, A.; Python, Q.; Strom, D.; Tavernier, S.; Van Doninck, W.; Van Mulders, P.; Van Onsem, G. P.; Van Parijs, I.; Brun, H.; Caillol, C.; Clerbaux, B.; De Lentdecker, G.; Fasanella, G.; Favart, L.; Goldouzian, R.; Grebenyuk, A.; Karapostoli, G.; Lenzi, T.; Léonard, A.; Maerschalk, T.; Marinov, A.; Perniè, L.; Randle-conde, A.; Seva, T.; Vander Velde, C.; Vanlaer, P.; Yonamine, R.; Zenoni, F.; Zhang, F.; Benucci, L.; Cimmino, A.; Crucy, S.; Dobur, D.; Fagot, A.; Garcia, G.; Gul, M.; Mccartin, J.; Ocampo Rios, A. A.; Poyraz, D.; Ryckbosch, D. et al.
Bibliographical reference
Physics Letters B, Volume 772, p. 489-511.
Advertised on:
9
2017
Citations
141
Refereed citations
99
Description
The cross section for coherent J / ψ photoproduction accompanied by
at least one neutron on one side of the interaction point and no neutron
activity on the other side, Xn0n, is measured with
the CMS experiment in ultra-peripheral PbPb collisions at
√{sNN} = 2.76TeV. The analysis is based on a data sample
corresponding to an integrated luminosity of 159μb-1,
collected during the 2011 PbPb run. The J / ψ mesons are
reconstructed in the dimuon decay channel, while neutrons are detected
using zero degree calorimeters. The measured cross section is
dσSUB>Xn0n/SUB>coh/dy (J /
ψ) = 0.36 ± 0.04(stat) ± 0.04(syst) mb in the rapidity
interval 1.8 < | y | < 2.3. Using a model for the relative rate of
coherent photoproduction processes, this Xn0n
measurement gives a total coherent photoproduction cross section of
dσcoh / dy (J / ψ) = 1.82 ± 0.22(stat)
± 0.20(syst) ± 0.19(theo) mb. The data strongly disfavor
the impulse approximation model prediction, indicating that nuclear
effects are needed to describe coherent J / ψ photoproduction in
γ + Pb interactions. The data are found to be consistent with the
leading twist approximation, which includes nuclear gluon shadowing.