Quasi-PDFs from Twisted mass fermions at the physical point

Abstract

We present results for the flavor non-singlet u-d parton distribution functions within the nucleon using the quasi-PDF approach. The lattice calculation is performed by employing the twisted mass formulation and two gauge ensembles, having $N_f=2$ and $N_f=2+1+1$ dynamical fermions with masses tuned to their physical value. For the $N_f=2$ physical point ensemble, the unpolarized, helicity and transversity distributions are computed for three values of the nucleon momentum, namely [6, 8, 10]$\pi /L$ corresponding to [0.83,1.11,1.38] GeV. Upon renormalization, we find that, as the nucleon momentum increases, the lattice results approach the phenomenological distributions resulting from analyses of deep inelastic scattering data, opening a promising path for a direct evaluation of parton distributions from the QCD Lagrangian. For the $N_f=2+1+1$ physical point ensemble, we present preliminary results for the unpolarized distribution extracted from a nucleon boosted by $8\pi /L$ or 0.97 GeV.

Comments: 7 pages, 6 figures, The 36th International Symposium on Lattice Field Theory (Lattice 2018)