From prompt to direct J/$\psi$ production: new insights on the ${\chi }_{c1}$ and ${\chi }_{c2}$ polarizations and feed-down contributions from a global-fit analysis of mid-rapidity LHC data

Abstract

While the prompt J/$\psi$ cross section and polarization have been measured with good precision as a function of transverse momentum, $p_{\mathrm{T}}$, those of the directly produced J/$\psi$ are practically unknown, given that the cross sections and polarizations of the ${\chi }_{c1}$ and ${\chi }_{c2}$ mesons, large indirect contributors to J/$\psi$ production, are only known with rather poor accuracy. The lack of precise measurements of the ${\chi }_{cJ}$ polarizations induces large uncertainties in the level of their feed-down contributions to the prompt J/$\psi$ yield, because of the polarization-dependent acceptance corrections. The experimental panorama of charmonium production can be significantly improved through a consistent and model-independent global analysis of existing measurements of J/$\psi$, $\psi$(2S) and ${\chi }_c$ cross sections and polarizations, faithfully respecting all the correlations and uncertainties. In particular, it is seen that the ${\chi }_{cJ}$ polarizations and feed-down fractions to J/$\psi$ production have a negligible dependence on the J/$\psi$ $p_{\mathrm{T}}$, with average values ${\lambda }_{\vartheta }^{{\chi }_{c1}}=0.55\pm 0.23$, ${\lambda }_{\vartheta }^{{\chi }_{c2}}=-0.39\pm 0.22$, $R^{{\chi }_{c1}}=(18.8\pm 1.4)\%$ and $R^{{\chi }_{c2}}=(6.5\pm 0.5)\%$. The analysis also shows that $(67.2\pm 1.9)\%$ of the prompt J/$\psi$ yield is due to directly-produced mesons, of polarization constrained to remarkably small values, ${\lambda }_{\vartheta }^{\mathrm{J}/\psi }=0.04\pm 0.06$.

Submitted to Eur. Phys. J. C

References in corpus (17)

• Heavy quarkonium: progress, puzzles, and opportunities
• Quarkonium production in the LHC era: a polarized perspective
• Measurement of Angular Distributions of Drell-Yan Dimuons in p + d Interaction at 800 GeV/c
• Measurement of J/psi and psi(2S) prompt double-differential cross sections in pp collisions at sqrt(s) = 7 TeV
• Measurement of $\psi (2S)$ polarisation in $pp$ collisions at $\sqrt{s}=7$ TeV
• Measurement of the relative prompt production rate of chi(c2) and chi(c1) in pp collisions at sqrt(s) = 7 TeV
• First Measurement of the Angular Coefficients of Drell-Yan $e^{+}{e}^{-}$ pairs in the Z Mass Region from $p\bar{p}$ Collisions at $\sqrt{s}$ = 1.96 TeV
• Measurement of Angular Distributions of Drell-Yan Dimuons in $p+p$ Interactions at 800 GeV/c
• Measurement of chi_c1 and chi_c2 production with sqrt(s) = 7 TeV pp collisions at ATLAS
• A Measurement of the Psi' to J/psi Production Ratio in 920 GeV Proton-Nucleus Interactions
• Angular distributions of leptons from J/psi's produced in 920 GeV fixed-target proton-nucleus collisions
• Measurement of the production cross-section of $\psi (2S)\to J/\psi (\to {\mu }^{+}{\mu }^{-}){\pi }^{+}{\pi }^{-}$ in $pp$ collisions at $\sqrt{s}=7$ TeV at ATLAS
• Determination of chi_c and chi_b polarizations from dilepton angular distributions in radiative decays
• Measurement of the production cross section ratio sigma(chi[b2](1P)) / sigma(chi[b1](1P)) in pp collisions at sqrt(s) = 8 TeV
• Measurement of the ${\rm Y}$ polarizations in $pp$ collisions at $\sqrt{s}$=7 and 8TeV
• Constraints on the ${\chi }_{c1}$ versus ${\chi }_{c2}$ polarizations in proton-proton collisions at $\sqrt{s}=$ 8 TeV
• NRQCD colour-octet expansion vs LHC quarkonium production: signs of a hierarchy puzzle?

Cited by in corpus (2)

• Measurement of the polarizations of prompt and non-prompt J/$\psi$ and $\psi$(2S) mesons produced in pp collisions at $\sqrt{s}$ = 13 TeV
• A technique to study the elastic and inelastic interaction of quarkonium with hadrons using femtoscopic correlations