Speaker
Simone Rodini
(PV & INFN)
Description
Higher-twist transverse-momentum dependent parton distributions (TMDs) go beyond the parton model description of a proton as they describe correlations between quarks and gluons. Higher-twist TMDs, however, turn out to be very elusive objects, as they are difficult to extract from experimental data. Twist-3 distributions can be decomposed as a sum of different contributions. In general, these contributions are separated into two different types: lower-twist (i.e. twist-2) contributions and pure twist-3 contributions. Most of the phenomenological parameterizations and models rely on the so called Wandzura-Wilczeck (WW) approximation, that set to zero the pure twist-3 contributions.
The WW approximation, however, remove the richness of the twist-3 distributions. I will show how the quark-gluon correlations (pure twist-3 contributions) entering the T-even chiral-odd distribution e(x,k⊥) and in the T-even chiral-even distribution f⊥(x,k⊥) can be calculated by using the formalism of light-front wave functions (LFWFs). The LFWFs that are considered include the parton’s orbital angular momentum dependence and an intrinsic, non-perturbative gluon contribution. These elements are fundamental in order to compute the pure twist-3 contributions.
The parametrization of the LFWFs is chosen by the comparison with the distribution amplitudes of the proton. The parameters of the LFWFs are fitted on the MMHT2014 parametrization for the valence-quark and gluon contributions to the unpolarized parton distribution f1(x). With these fit parameters, I will show predictions of the pure twist-3 contributions, and I will compare the results for e(x) to a recent extraction, obtained from the analysis of preliminary data of the beam asymmetry for di-hadron semi-inclusive deep inelastic scattering at CLAS 6 GeV.
Primary author
Simone Rodini
(PV & INFN)
Co-author
Barbara Pasquini
(PV)
