The Spectrum and Structure of Hadrons

PI Robert Edwards , Jefferson Laboratory
Co-PI Raul Briceno, Old Dominion University
Chris Monahan, William and Mary
Kostas Orginos, William and Mary
Edwards ALCC Graphic

Wall–clock times for a problem with 643 ×128 lattice sites, comparing performance between Titan
(red bars) and Summit (green). The left pair of bars shows the wall-clock time for the original benchmark,
moved between the machines, whereas the right pair shows the effects of code and algorithmic optimizations and the molecular dynamics retuning.

Project Summary

Using Polaris at the Argonne Leadership Computing Facility, this team will compute the structure and spectrum of strongly-coupled hadronic states directly from the fundamental theory describing the interactions of quarks and gluons – the fundamental particles of nuclear matter. These calculations will provide essential theoretical support to the experimental program of the Thomas Jefferson National Accelerator Facility (Jefferson Lab) including the CLAS12 and GlueX experiments, and to the future Electron Ion Collider (EIC) at Brookhaven National Laboratory.

Project Description

The team has four goals. First, to compute the Bjorken x-dependent, isovector light-quark generalized parton distributions (GPDs) of the nucleon, in the continuum and physical quark-mass limits of lattice Quantum Chromo-Dynamics. Second, to provide a lattice determination of the flavor decomposition of the proton sea through isoscalar GPDs. Third, to calculate hadronic scattering amplitudes for scattering in the isospin 0, 1 and 2 channels and for KK scattering in the isospin 0 and 1 channels. Fourth, to obtain the first determination of radiative transitions for isovector and isoscalar mesons from lattice QCD.

Breakthrough advances in algorithms and computational implementations exploiting the capabilities of the Summit heterogeneous computing system have accelerated this project. The software has been developed largely under DOE SciDAC, the DOE Exascale Computing Project, and in collaboration with researchers at Nvidia. The project team is made up of both theoretical nuclear physicists, and computational scientists at the forefront of leadership-class computing.

Leadership class computing is critical for our goals, which will provide the ab initio answers to a question “essential for understanding the nature of visible matter” and central to the Department of Energy's experimental nuclear physics program: how do quarks and gluons form the wide range of hadronic bound states we observe in experiment?