Jul 26 – 30, 2021
US/Eastern timezone

Quark spin-orbit correlations in the proton

Jul 29, 2021, 10:15 PM
15m
Oral presentation Hadron Structure Hadron Structure

Speaker

Michael Engelhardt

Description

Generalized transverse momentum-dependent parton distributions (GTMDs) provide a comprehensive framework for imaging the internal structure of the proton. In particular, by encoding the simultaneous distribution of quark transverse positions and momenta, they allow one to directly access longitudinal quark orbital angular momentum, and, moreover, to correlate it with the quark helicity. The relevant GTMD is evaluated through a lattice calculation of a proton matrix element of a quark bilocal operator (the separation in which is Fourier conjugate to the quark momentum) featuring a momentum transfer (which is Fourier conjugate to the quark position), as well as the Dirac structure appropriate for capturing the quark helicity. The weighting by quark transverse position requires a derivative with respect to momentum transfer, which is obtained in unbiased fashion using a direct derivative method. The lattice calculation is performed directly at the physical pion mass, using domain wall fermions to mitigate operator mixing effects. Both the Jaffe-Manohar as well as the Ji quark spin-orbit correlations are extracted, yielding evidence for a strong quark spin-orbit coupling in the proton.

Primary authors

Michael Engelhardt Jeremy Green (CERN) Nesreen Hasan (University of Wuppertal) Taku Izubuchi (Brookhaven National Laboratory) Christos Kallidonis (Thomas Jefferson National Accelerator Facility) Stefan Krieg (Forschungszentrum Juelich GmbH) Simonetta Liuti (University of Virginia) Stefan Meinel (University of Arizona) John Negele (Massachusetts Institute of Technology) Andrew Pochinsky (Massachusetts Institute of Technology) Abha Rajan (Old Dominion University) Giorgio Silvi (University of Wuppertal) Sergey Syritsyn (Stony Brook University)

Presentation materials