The Secret Life of Quarks
The National Computational Infrastructure for Lattice Gauge Theory

Studying the theory of quarks and gluons formulated on a space-time lattice using Lattice Quantum Chromodynamics

Paul Mackenzie (project webpage)
University of California at Santa Barbara

The long term goals of high energy and nuclear physicists are to identify the fundamental building blocks of matter, and to determine the interactions among them that lead to the physical world we observe. Remarkable progress has been made through the development of the Standard Model of Particles and Interactions, which provides fundamental theories of the strong, electromagnetic and weak interactions. However, our understanding of the Standard Model is incomplete because it has proven extremely difficult to determine many of the predictions of Quantum ChromoDynamics (QCD), the component of the Standard Model that describes the strong interactions.

Despite its extraordinary success, the Standard Model is believed to be only the low energy (long distance) limit of a more fundamental theory. Therefore, a major component of the experimental program in high energy physics is devoted to making precise tests of the Standard Model in order to determine its range of validity and search for indications of new physics beyond it. Many of these tests require both accurate experiments and accurate QCD calculations of the effects of the strong interactions on weak interaction processes. In almost all cases, the precision of the tests are limited by the uncertainties in the QCD calculations, rather than in the experiments.

To understand the most important predictions of QCD, those that depend on the strong coupling regime of the theory, from first principles and with controlled systematic errors requires large scale numerical simulations within the framework of lattice gauge theory. Such simulations are needed to address problems that are at the heart of the DOE’s large experimental programs in high energy and nuclear physics. The long range goal of this initiative is to construct the computational infrastructure needed for the study of quantum chromodynamics (QCD). A very successful start was made under the first round of SciDAC investments. This project will build on those successes to address new challenges that must be met to advance the study of QCD. The immediate objectives of this project are to 1) calculate weak interaction matrix elements to the accuracy needed to make precise tests of the Standard Model; 2) determine the properties of strongly interacting matter under extreme conditions such as those that existed in the very early development of the universe, and are created today in relativistic heavy ion collisions; and 3) calculate the masses of strongly interacting particles and obtain a quantitative understanding of their internal structure.

The study of the Standard Model is at the core of the Department of Energy's experimental programs in high energy and nuclear physics. Major goals are to verify the Standard Model or discover its limits; determine the properties of strongly interacting matter under extreme conditions; and understand the structure of nucleons and other strongly interacting particles. Lattice QCD calculations are essential to research in all of these areas.

Science Application: Quantum Chromodynamics

Project Title: National Computational Infrastructure for Lattice Gauge Theory

Principal Investigator: Paul Mackenzie
Affiliation: Fermi National Accelerator Laboratory

Project Webpage:

Participating Institutions and Co-Investigators:
Boston University - Richard Brower and Claudio Rebbi
Brookhaven National Laboratory - Michael Creutz
DePaul University - Massimo DiPierro
Fermi National Accelerator Laboratory - Paul Mackenzie (PI)
Illinois Institute of Technology - Xian-He Sun
Indiana University - Steven Gottlieb
Massachusetts Institute of Technology - John Negele
Thomas Jefferson National Accelerator Facility - David Richards and William (Chip) Watson
University of Arizona - Doug Toussaint
University of California, Santa Barbara - Robert Sugar
University of North Carolina - Daniel Reed
University of Utah - Carleton DeTar
Vanderbilt University - Theodore Bapty

Funding Partners: U.S. Department of Energy, Office of Science, Advanced Scientific Computing Research, High Energy Physics, and Nuclear Physics

Budget and Duration: Approximately $2.2 Million per year for five years 1

Other SciDAC physics efforts

1Subject to acceptable progress review and the availability of appropriated funds


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