Speaker
Description
We present the first calculation of twist-3 axial quark GPDs of the proton using lattice QCD combined with the large momentum effective theory (LaMET) approach. We use one ensemble of twisted mass fermions with degenerate light quarks, a strange and a charm quark, at a single lattice spacing of 0.093 fm and a pion mass of 260 MeV. We employ three proton boosts up to 1.67 GeV to test the convergence of the LaMET expansion. The light-cone twist-3 GPDs are defined in the symmetric frame, at negative momentum transfers squared of 0.69, 1.38 and 2.76 GeV^2 and at zero skewness. We extract the leading combinations of twist-3 axial GPDs and twist-2 helicity GPDs and we isolate some of the twist-3 ones, confirming that one of them vanishes at zero skewness. We also perform several consistency checks, such as the local limit of the extracted GPDs and the Burkhardt-Cottingham-type and Efremov-Teryaev-Leader-type sum rules.
