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A<sc>bstract</sc> The production of inclusive, prompt and non-prompt J/ψwas studied for the first time at midrapidity (−1.37< ycms<0.43) in p-Pb collisions at$$ \sqrt{s_{\textrm{NN}}} $$ = 8.16 TeV with the ALICE detector at the LHC. The inclusive J/ψmesons were reconstructed in the dielectron decay channel in the transverse momentum (pT) interval 0< pT<14 GeV/cand the prompt and non-prompt contributions were separated on a statistical basis forpT>2 GeV/c. The study of the J/ψmesons in the dielectron channel used for the first time in ALICE online single-electron triggers from the Transition Radiation Detector, providing a data sample corresponding to an integrated luminosity of 689 ± 13μb−1. The proton-proton reference cross section for inclusive J/ψwas obtained based on interpolations of measured data at different centre-of-mass energies and a universal function describing thepT-differential J/ψproduction cross sections. ThepT-differential nuclear modification factorsRpPbof inclusive, prompt, and non-prompt J/ψare consistent with unity and described by theoretical models implementing only nuclear shadowing.
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Energy dependence of coherent photonuclear production of J/ψ mesons in ultra-peripheral Pb-Pb collisions at $$ \sqrt{{\textrm{s}}_{\textrm{NN}}} $$ = 5.02 TeV
A<sc>bstract</sc> The cross section for coherent photonuclear production of J/ψis presented as a function of the electromagnetic dissociation (EMD) of Pb. The measurement is performed with the ALICE detector in ultra-peripheral Pb-Pb collisions at a centre-of-mass energy per nucleon pair of$$ \sqrt{{\textrm{s}}_{\textrm{NN}}} $$ = 5.02 TeV. Cross sections are presented in five different J/ψrapidity ranges within |y| < 4, with the J/ψreconstructed via its dilepton decay channels. In some events the J/ψis not accompanied by EMD, while other events do produce neutrons from EMD at beam rapidities either in one or the other beam direction, or in both. The cross sections in a given rapidity range and for different configurations of neutrons from EMD allow for the extraction of the energy dependence of this process in the range 17 <WγPb,n< 920 GeV, whereWγPb,nis the centre-of-mass energy per nucleon of theγPb system. This range corresponds to a Bjorken-xinterval spanning about three orders of magnitude: 1.1 × 10−5<x< 3.3 × 10−2. In addition to the ultra-peripheral and photonuclear cross sections, the nuclear suppression factor is obtained. These measurements point to a strong depletion of the gluon distribution in Pb nuclei over a broad, previously unexplored, energy range. These results, together with previous ALICE measurements, provide unprecedented information to probe quantum chromodynamics at high energies.
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- PAR ID:
- 10514846
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Publisher / Repository:
- link.springer.com
- Date Published:
- Journal Name:
- Journal of High Energy Physics
- Volume:
- 2023
- Issue:
- 10
- ISSN:
- 1029-8479
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1007/JHEP10(2023)119
