PoS - Proceedings of Science
Volume 396 - The 38th International Symposium on Lattice Field Theory (LATTICE2021) - Oral presentation
First study of twist-3 PDFs for the proton from lattice QCD
M. Constantinou*, S. Bhattacharya, K. Cichy, A. Metz, A. Scapellato and F. Steffens
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Pre-published on: May 16, 2022
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Abstract
In these proceedings, we summarize the main results from the first-ever calculations of the chiral-even and chiral-odd twist-3 parton distributions, $g_T(x)$ and $h_L(x)$, of the proton from lattice QCD.
We use an $N_f=2+1+1$ ensemble of maximally twisted mass fermions with a clover improvement.
The lattice has a spatial extent of 3~fm, the lattice spacing is 0.093~fm, and the pion mass is $260$~MeV. The matrix elements are obtained with a source-sink time separation of 1.12~fm to control contamination from excited states. The calculation is based on the quasi-PDF approach and employs three values for the proton momentum: 0.83~GeV, 1.25~GeV, and 1.67~GeV.
The lattice data are renormalized non-perturbatively using the RI$'$ scheme, and the final results are presented in the $\overline{\rm MS}$ scheme at the scale of 2~GeV. Furthermore, we compute in the same setup the helicity, $g_1(x)$, and transversity, $h_1(x)$, distributions, which are used to compare $g_T(x)$ and $h_L(x)$ to their Wandzura-Wilczek approximations. For $h_L(x)$, we combine results for the isovector and isoscalar flavor combinations to disentangle the individual up- and down-quark contributions.
DOI: https://doi.org/10.22323/1.396.0391
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