On the use of a running coupling in the NLO calculation of forward hadron production

Abstract

We address and solve a puzzle raised by a recent calculation [1] of the cross-section for particle production in proton-nucleus collisions to next-to-leading order: the numerical results show an un- reasonably large dependence upon the choice of a prescription for the QCD running coupling, which spoils the predictive power of the calculation. Specifically, the results obtained with a prescription formulated in the transverse coordinate space differ by one to two orders of magnitude from those obtained with a prescription in momentum space. We show that this discrepancy is an artefact of the interplay between the asymptotic freedom of QCD and the Fourier transform from coordinate space to momentum space. When used in coordinate space, the running coupling can act as a fictitious potential which mimics hard scattering and thus introduces a spurious contribution to the cross-section. We identify a new coordinate-space prescription which avoids this problem and leads to results consistent with those obtained with the momentum-space prescription.

28 pages, 9 figures, 2 appendices

References in corpus (12)

• The Color Glass Condensate
• NLO evolution of color dipoles
• Quark contribution to the small-$x$ evolution of color dipole
• Triumvirate of Running Couplings in Small-x Evolution
• Resumming double logarithms in the QCD evolution of color dipoles
• Direct numerical solution of the coordinate space Balitsky-Kovchegov equation at next to leading order
• Single-inclusive particle production in proton-nucleus collisions at next-to-leading order in the hybrid formalism
• CGC factorization for forward particle production in proton-nucleus collisions at next-to-leading order
• Quark loop contribution to BFKL evolution: Running coupling and leading-N_f NLO intercept
• Dipole factorization for DIS at NLO: Combining the $q\bar{q}$ and $q\bar{q}g$ contributions
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• Matching Collinear and Small-x Factorization Calculations for Inclusive Hadron Production in pA Collisions

Cited by in corpus (28)

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• Color Glass Condensate at next-to-leading order meets HERA data
• HERA data and collinearly-improved BK dynamics
• Low $x$ physics as an infinite twist (G)TMD framework: unravelling the origins of saturation
• Quarks at next-to-eikonal accuracy in the CGC I: Forward quark-nucleus scattering
• Pursuing the Precision Study for Color Glass Condensate in Forward Hadron Productions
• Inclusive prompt photon production in electron-nucleus scattering at small x
• High-energy emissions of light mesons plus heavy flavor at the LHC and the Forward Physics Facility
• Forward dijets in proton-nucleus collisions at next-to-leading order: the real corrections
• Forward trijet production in proton-nucleus collisions
• Next-to-leading order Balitsky-Kovchegov equation beyond large $N_{\mathrm{c}}$
• Single Inclusive Jet Production in $pA$ Collisions at NLO in the small-$x$ regime
• Saturation and forward jets in proton-lead collisions at the LHC
• Exclusive photoproduction of vector meson at next-to-leading order from Color Glass Condensate
• Forward Inclusive Jet Productions in pA Collisions
• Measurement of inclusive very forward jet cross sections in proton-lead collisions at $\sqrt{s_{\mathrm{NN}}}=$ 5.02 TeV
• On the Threshold Resummation in Forward pA Collisions
• Single inclusive jet production and the nuclear modification ratio at very forward rapidity in proton-lead collisions with $\sqrt{s_{NN}}$ = 5.02 TeV
• Complete Next-to-Leading Order Calculation of Single Inclusive ${\pi }^0$ Production in Forward Proton-Nucleus Collisions
• Quark TMDs from back-to-back dijet production at forward rapidities in pA collisions beyond eikonal accuracy in the CGC
• Complete calculation of exclusive heavy vector meson production at next-to-leading order in the dipole picture
• Exclusive heavy vector meson production at next-to-leading order in the dipole picture
• Unequal rapidity correlators in the dilute limit of JIMWLK
• On the use of a running coupling in the calculation of forward hadron production at next-to-leading order
• Kaon production in high multiplicity events at the LHC
• Computation of the one-loop spectral QCD running coupling using covariant spectral regularization
• Exclusive production of light vector mesons at next-to-leading order in the dipole picture
• Forward rapidity isolated photon production in proton-nucleus collisions