Testing the universality of the Collins function in pion-jet production at RHIC

Abstract

By adopting a generalised parton model approach at leading order in QCD, including spin and intrinsic parton motion effects, we study the Collins azimuthal asymmetries for pions within a large-$p_T$ jet produced at mid-rapidity in polarised hadronic collisions. Using available information on the quark transversity distributions and the pion Collins functions, as extracted from semi-inclusive deeply inelastic scattering and $e^{+}{e}^{-}\to h_1{h}_{2}X$ processes, we compute estimates for the Collins asymmetries in kinematical configurations presently investigated at RHIC by the STAR Collaboration. Collins-like asymmetries, involving linearly polarised gluons, are also considered. Our predictions, compared against available preliminary data, show a very good agreement, even if some discrepancies, to be further scrutinized both theoretically and experimentally, appear in the transverse momentum dependence of the Collins asymmetry. These results are in favour of the predicted universality of the Collins function and of a mild, if any, evolution with the hard scale of the asymmetries.

10 pages, 5 figures (10 plots); v2: discussion on jet kT dependence of the SSAs extended and one plot on the corresponding unpolarized cross section added (Fig. 3, right panel); few comments on factorization breaking effects and on the universality issue of the Collins function added; three references added; results unchanged; matches the published version

References in corpus (11)

• Global analysis of fragmentation functions for pions and kaons and their uncertainties
• Sivers Effect for Pion and Kaon Production in Semi-Inclusive Deep Inelastic Scattering
• k_T factorization is violated in production of high-transverse-momentum particles in hadron-hadron collisions
• Single transverse-spin asymmetry in high transverse momentum pion production in pp collisions
• Transverse-Spin and Transverse-Momentum Effects in High-Energy Processes
• Azimuthal and Single Spin Asymmetries in Hard Scattering Processes
• Azimuthal Asymmetric Distribution of Hadrons Inside a Jet at Hadron Collider
• Collins azimuthal asymmetries of hadron production inside jets
• Connecting Different TMD Factorization Formalisms in QCD
• Azimuthal asymmetries for hadron distributions inside a jet in hadronic collisions
• Simultaneous extraction of transversity and Collins functions from new SIDIS and e+e- data

Cited by in corpus (11)

• The Present and Future of QCD
• Polarized jet fragmentation functions
• Azimuthal transverse single-spin asymmetries of inclusive jets and identified hadrons within jets from polarized $pp$ collisions at $\sqrt{s}$ = 200 GeV
• Measurement of lepton-jet correlation in deep-inelastic scattering with the H1 detector using machine learning for unfolding
• Accessing nucleon transversity with one-point energy correlators
• Transverse spin polarization as a novel probe of medium-induced transverse-momentum-broadening effect
• Collins function for pion-in-jet production in polarized $pp$ collisions: a test of universality and factorization
• Probing nucleon spin structure in deep-inelastic scattering, proton-proton collisions and Drell-Yan processes
• Measurement of Transverse Spin Dependent Azimuthal Correlations of Charged Pion(s) in $p^{\uparrow }p$ Collisions at $\sqrt{s}=200$ GeV at STAR
• Collins asymmetries for pion-in-jet production in polarized $\ell p$ collisions at the EIC
• Exploring the Quark Transversity and the Collins Fragmentation Functions using Polarized $pp$ Collisions at STAR