Abstract
We present the first exploratory lattice quantum chromodynamics (QCD) calculation of the polarized gluon Ioffe-time pseudodistribution in the nucleon. The Ioffe-time pseudodistribution provides a frame-independent and gauge-invariant framework to determine the gluon helicity in the nucleon from first principles. We employ a high-statistics computation using a 323×64 lattice ensemble characterized by a 358 MeV pion mass and a 0.094 fm lattice spacing. We establish the pseudodistribution approach as a feasible method to address the proton spin puzzle with successive improvements in statistical and systematic uncertainties anticipated in the future. Within the statistical precision of our data, we find a good comparison between the lattice determined polarized gluon Ioffe-time distribution and the corresponding expectations from the state-of-the-art global analyses. We find a hint for a nonzero gluon spin contribution to the proton spin from the model-independent extraction of the gluon helicity pseudodistribution over a range of Ioffe-time, ν≲9.
| Original language | English |
|---|---|
| Article number | 094511 |
| Journal | Physical Review D |
| Volume | 106 |
| Issue number | 9 |
| DOIs | |
| State | Published - Nov 1 2022 |
Funding
We would like to thank all the members of the HadStruc collaboration for fruitful and stimulating exchanges. T. K. and R. S. S. acknowledge Luka Leskovec and Yiyu Zhou for offering their expertise, which greatly assisted this research. This work is supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Contract No. DE-AC05-06OR23177. J. K. is supported by U.S. DOE Grant No. DE-SC0011941. N. K., K. O., and R. S. S. are supported by U.S. DOE Grant No. DE-FG02-04ER41302. A. R. and W. M. are also supported by U.S. DOE Grant No. DE-FG02-97ER41028. Computations for this work were carried out in part on facilities of the USQCD Collaboration, which are funded by the Office of Science of the U.S. Department of Energy. This work was performed in part using computing facilities at William and Mary which were provided by contributions from the National Science Foundation (MRI Grant No. PHY-1626177), and the Commonwealth of Virginia Equipment Trust Fund. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation Grant No. CI-1548562. Specifically, it used the Bridges system, which is supported by NSF Grant No. ACI-1445606, at the Pittsburgh Supercomputing Center (PSC) . In addition, this work used resources at NERSC, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231, as well as resources of the Oak Ridge Leadership Computing Facility at the Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC05-00OR22725. The software codes chroma , quda and qp hi x were used in our work. The authors acknowledge support from the U.S. Department of Energy, Office of Science, Office of Advanced Scientific Computing Research and Office of Nuclear Physics, Scientific Discovery through Advanced Computing (SciDAC) program, and of the U.S. Department of Energy Exascale Computing Project. The authors also acknowledge the Texas Advanced Computing Center (TACC) at The University of Texas at Austin for providing HPC resources, like Frontera computing system that has contributed to the research results reported within this paper. We acknowledge PRACE (Partnership for Advanced Computing in Europe) for awarding us access to the high performance computing system Marconi100 at CINECA (Consorzio Interuniversitario per il Calcolo Automatico dellItalia Nord-orientale) under the Grants No. Pra21-5389 and No. Pra23-0076. This work also benefited from access to the Jean Zay supercomputer at the Institute for Development and Resources in Intensive Scientific Computing (IDRIS) in Orsay, France under Project No. A0080511504.