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 dσXjavax.xml.bind.JAXBElement@4a5a09420javax.xml.bind.JAXBElement@2618a9e3coh/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.

Khachatryan, V., Sirunyan, A., Tumasyan, A., Adam, W., Asilar, E., Bergauer, T., et al. (2017). Coherent J/ψ photoproduction in ultra-peripheral PbPb collisions at sNN=2.76TeV with the CMS experiment. PHYSICS LETTERS. SECTION B, 772, 489-511 [10.1016/j.physletb.2017.07.001].

Coherent J/ψ photoproduction in ultra-peripheral PbPb collisions at sNN=2.76TeV with the CMS experiment

Brianza, L.;Dinardo, M. E.;Fiorendi, S.;Gerosa, R.;Ghezzi, A.;Govoni, P.;Manzoni, R. A.;Marzocchi, B.;Paganoni, M.;Pigazzini, S.;Ragazzi, S.;Tabarelli de Fatis, T.;De Guio, F.;Lucchini, M. T.;
2017

Abstract

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 dσXjavax.xml.bind.JAXBElement@4a5a09420javax.xml.bind.JAXBElement@2618a9e3coh/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.
Articolo in rivista - Articolo scientifico
CMS; Heavy ion collisions; J/Psi; Physics; Ultra-peripheral collisions; UPC;
CMS; Heavy ion collisions; J/Psi; Physics; Ultra-peripheral collisions; UPC; Nuclear and High Energy Physics
English
2017
772
489
511
none
Khachatryan, V., Sirunyan, A., Tumasyan, A., Adam, W., Asilar, E., Bergauer, T., et al. (2017). Coherent J/ψ photoproduction in ultra-peripheral PbPb collisions at sNN=2.76TeV with the CMS experiment. PHYSICS LETTERS. SECTION B, 772, 489-511 [10.1016/j.physletb.2017.07.001].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/187980
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