Centrality dependence of J/ψ and ψ(2S) production and nuclear modification in p-Pb collisions at $$ \sqrt{s_{\mathrm{NN}}} $$ = 8.16 TeV
抄録
<jats:title>A<jats:sc>bstract</jats:sc> </jats:title><jats:p>The inclusive production of the J/<jats:italic>ψ</jats:italic> and <jats:italic>ψ</jats:italic>(2S) charmonium states is studied as a function of centrality in p-Pb collisions at a centre-of-mass energy per nucleon pair <jats:inline-formula><jats:alternatives><jats:tex-math>$$ \sqrt{s_{\mathrm{NN}}} $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:msub> <mml:mi>s</mml:mi> <mml:mi>NN</mml:mi> </mml:msub> </mml:msqrt> </mml:math></jats:alternatives></jats:inline-formula> = 8<jats:italic>.</jats:italic>16 TeV at the LHC. The measurement is performed in the dimuon decay channel with the ALICE apparatus in the centre-of-mass rapidity intervals <jats:italic>−</jats:italic>4<jats:italic>.</jats:italic>46 <jats:italic>< y</jats:italic><jats:sub>cms</jats:sub><jats:italic>< −</jats:italic>2<jats:italic>.</jats:italic>96 (Pb-going direction) and 2<jats:italic>.</jats:italic>03 <jats:italic>< y</jats:italic><jats:sub>cms</jats:sub><jats:italic><</jats:italic> 3<jats:italic>.</jats:italic>53 (p-going direction), down to zero transverse momentum (<jats:italic>p</jats:italic><jats:sub>T</jats:sub>). The J/<jats:italic>ψ</jats:italic> and <jats:italic>ψ</jats:italic>(2S) production cross sections are evaluated as a function of the collision centrality, estimated through the energy deposited in the zero degree calorimeter located in the Pb-going direction. The <jats:italic>p</jats:italic><jats:sub>T</jats:sub>-differential J/<jats:italic>ψ</jats:italic> production cross section is measured at backward and forward rapidity for several centrality classes, together with the corresponding average ⟨<jats:italic>p</jats:italic><jats:sub>T</jats:sub>⟩ and <jats:inline-formula><jats:alternatives><jats:tex-math>$$ \left\langle {p}_{\mathrm{T}}^2\right\rangle $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mfenced> <mml:msubsup> <mml:mi>p</mml:mi> <mml:mi>T</mml:mi> <mml:mn>2</mml:mn> </mml:msubsup> </mml:mfenced> </mml:math></jats:alternatives></jats:inline-formula> values. The nuclear effects affecting the production of both charmonium states are studied using the nuclear modification factor. In the p-going direction, a suppression of the production of both charmonium states is observed, which seems to increase from peripheral to central collisions. In the Pb-going direction, however, the centrality dependence is different for the two states: the nuclear modification factor of the J/<jats:italic>ψ</jats:italic> increases from below unity in peripheral collisions to above unity in central collisions, while for the <jats:italic>ψ</jats:italic>(2S) it stays below or consistent with unity for all centralities with no significant centrality dependence. The results are compared with measurements in p-Pb collisions at <jats:inline-formula><jats:alternatives><jats:tex-math>$$ \sqrt{s_{\mathrm{NN}}} $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:msub> <mml:mi>s</mml:mi> <mml:mi>NN</mml:mi> </mml:msub> </mml:msqrt> </mml:math></jats:alternatives></jats:inline-formula> = 5<jats:italic>.</jats:italic>02 TeV and no significant dependence on the energy of the collision is observed. Finally, the results are compared with theoretical models implementing various nuclear matter effects.</jats:p>
収録刊行物
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- Journal of High Energy Physics
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Journal of High Energy Physics 2021 (2), 2021-02
Springer Science and Business Media LLC