Transverse-momentum dependent parton distribution functions beyond leading twist in quark models

Abstract

Higher-twist transverse momentum dependent parton distribution functions (TMDs) are a valuable probe of the quark-gluon dynamics in the nucleon, and play a vital role for the explanation of sizable azimuthal asymmetries in hadron production from unpolarized and polarized deep-inelastic lepton-nucleon scattering observed in experiments at CERN, DESY and Jefferson Lab. The associated observables are challenging to interpret, and still await a complete theoretical explanation, which makes guidance from models valuable. In this work we establish the formalism to describe unpolarized higher-twist TMDs in the light-front framework based on a Fock-space expansion of the nucleon state in terms of free on-shell parton states. We derive general expressions and present numerical results in a practical realization of this picture provided by the light-front constituent quark model. We review several other popular quark model approaches including free quark ensemble, bag, spectator and chiral quark-soliton model. We discuss how higher-twist TMDs are described in these models, and obtain results for several TMDs not discussed previously in literature. This study contributes to the understanding of non-perturbative properties of subleading twist TMDs. The results from the light-front constituent quark model are also compared to available phenomenological information, showing a satisfactory agreement.

25 pages, 3 figures, 2 tables; misprints corrected. Close to published version, except for Eq.(65) (c.f. footnote 3) which could not be fixed in time during proof-reading

References in corpus (7)

• Transverse-Spin and Transverse-Momentum Effects in High-Energy Processes
• Unified framework for generalized and transverse-momentum dependent parton distributions within a 3Q light-cone picture of the nucleon
• Measurement of Single and Double Spin Asymmetries in Deep Inelastic Pion Electroproduction with a Longitudinally Polarized Target
• Nucleon spin densities in a light-front constituent quark model
• Transverse momentum dependence of semi-inclusive pion production
• Light-cone divergence in twist-3 correlation functions
• Higher Twist Contributions to the Structure Functions F_2^p(x,Q^2) and F_2^d(x,Q^2) at Large x and Higher Orders

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• Structure of the nucleon at leading and subleading twist in the covariant parton model
• New determination of $\mathcal{S}\mathcal{T}⟨N|\overline{q}{D}_{\mu }{D}_{\nu }q|N⟩$ based on recent experimental constraints
• Leading and higher twist transverse momentum dependent parton distribution functions in the spectator model