$J/\psi$ production at NLO with a scale-dependent color-evaporation model

Abstract

Nearly ten years ago, Kang, Ma, Qiu, and Sterman derived an evolution equation for a $Q\bar{Q}$ pair fragmenting into a quarkonium. In this study we explore the consequence of this evolution for the color-evaporation model, focusing on $J/\psi$ transverse-momentum ($p_t$) distributions in proton-proton collisions. We show that, as expected, it softens the spectrum obtained by fixed-order calculations. While next-to-leading-order calculations strongly overestimate data at large $p_t$, ours, including the (approximate) $Q\bar{Q}$ evolution and next-to-leading-order cross sections computed with Madgraph, are in good agreement with experiments. Since our study with the color-evaporation model shows a significant effect of the $Q\bar{Q}$ evolution at large $p_t$, a determination of scale-dependent long-distance-matrix elements of non-relativistic QCD could be necessary. To describe data at small and intermediate $p_t$, we use the $k_t$-factorization approach, and we argue that quarkonia data could help constrain unintegrated parton densities.

arXiv comment24 pages, 16 figures

References in corpus (43)

• PYTHIA 6.4 Physics and Manual
• PYTHIA 6.2 Physics and Manual
• The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations
• Rigorous QCD Analysis of Inclusive Annihilation and Production of Heavy Quarkonium
• New parton distribution functions from a global analysis of quantum chromodynamics
• Unintegrated parton distributions
• Measurement of J/psi production in pp collisions at sqrt(s)=7 TeV
• Unintegrated parton distributions and inclusive jet production at HERA
• The CCFM Monte Carlo generator CASCADE 2.2.0
• J/psi Production vs Transverse Momentum and Rapidity in p+p Collisions at sqrt(s) = 200 GeV
• New Observables in Inclusive Production of Quarkonia
• J/psi and psi(2S) production in pp collisions at sqrt(s) = 7 TeV
• Soft-gluon resolution scale in QCD evolution equations
• Collinear and TMD parton densities from fits to precision DIS measurements in the parton branching method
• Quarkonium Production in an Improved Color Evaporation Model
• Heavy quarkonium production and polarization
• Measurement of forward $J/\psi$ production cross-sections in $pp$ collisions at $\sqrt{s}=13$ TeV
• Heavy Quarkonium Production at Collider Energies: Factorization and Evolution
• Measurement of prompt J/psi and beauty hadron production cross sections at mid-rapidity in pp collisions at sqrt(s) = 7 TeV
• Collinear and TMD Quark and Gluon Densities from Parton Branching Solution of QCD Evolution Equations
• Measurement of the differential cross-sections of prompt and non-prompt production of $J/\psi$ and $\psi (2\mathrm{S})$ in $pp$ collisions at $\sqrt{s}=7$ and $8$ TeV with the ATLAS detector
• Production of Z-bosons in the parton branching method
• Comparison of the color-evaporation model and the NRQCD factorization approach in charmonium production
• Production and polarization of prompt $J/\psi$ in the improved color evaporation model using the $k_T$-factorization approach
• Proper TMD factorization for quarkonia production: $pp\to {\eta }_{c,b}$ as a study case
• NRQCD Confronts LHCb Data on Quarkonium Production within Jets
• The Systematics of Quarkonium Production at the LHC and Double Parton Fragmentation
• Probing Quarkonium Production Mechanisms with Jet Substructure
• Dynamical resolution scale in transverse momentum distributions at the LHC
• Heavy Quarkonium Production at Collider Energies: Partonic Cross Section and Polarization
• CASCADE3 A Monte Carlo event generator based on TMDs
• Prompt J/psi production in the Regge limit of QCD: From Tevatron to LHC
• Prompt J/Psi production at LHC: new evidence for the kt-factorization
• Are there any challenges in the charmonia production and polarization at the LHC?
• Complete NLO QCD study of single- and double-quarkonium hadroproduction in the colour-evaporation model at the Tevatron and the LHC
• Anomalous dimensions of the double parton fragmentation functions
• Pathologies of the KMR prescriptions for unintegrated PDFs: Which prescription should be preferred?
• $J/\psi$-meson production within improved color evaporation model with the $k_T$-factorization approach for $c\bar{c}$ production
• Single and pair $J/\psi$ production in the Improved Color Evaporation Model using the Parton Reggeization Approach
• Prompt inclusive production of $J/\psi$, ${\psi }^{\prime }$ and ${\chi }_c$ mesons at the LHC in forward directions within the NRQCD $k_t$-factorization approach - search for the onset of gluon saturation
• Multi-jet Merging with TMD Parton Branching
• Heavy-quark production with $k_t$-factorization: The importance of the sea-quark distribution
• Subleading power corrections to heavy quarkonium production in QCD factorization approach

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