We study physics of the strong force, one of the four
fundamental forces in nature (the other three are gravity, electromagnetism, and the weak force).
The underlying theory of the strong force is called quantum chromodynamics (QCD)
which governs the interactions of quarks and gluons, the fundamental building blocks of all matter.
We try to answer questions like
What is the excitation spectrum of QCD? For example, how does the proton get its mass?
(Answer: Proton is a "ball of energy" according to Einstein's E=mc2.)
How rigid is the proton? How does the charge distribute inside the proton? This can be studied by placing the proton in an electric or magnetic field and study its response (moments and polarizabilities).
What is the nature of the nuclear force? How does a resonance form? We study this by computing scattering phase shifts between hadrons.
What are the phases of nuclear matter at finite temperature and density? This is relevant to the understanding of early universe and neutron stars.
What is the structure of the QCD vacuum? Vacuum is not empty:
it's full of fluctuations of quark and gluon fields that affect hadron structure drastically.
We perform calculations on supercomputers by approximating continuous space-time with a discrete 4-dimensional lattice (this is called lattice QCD). We develop our own software package called GWU-QCD that can run on a variety of computing architectures.
We even build our own high-performance computer clusters using CPUs and graphics cards (GPUs) in collaboration with computer scientists. Our research is funded in part by U.S. Department of Energy and National Science Foundation.
We maintain a wiki page (see link at the top-right corner).
We can involve graduate as well as undergraduate students in research projects. If you are interested in doing research in our group, please contact Prof. Lee (email@example.com) or Prof. Alexandru (firstname.lastname@example.org).
The Big Picture
We study the structure of matter on length scales of a femtometer (10-15m or 1 millionth nanometer), deep inside the heart of the atom:
Study of the very small is closely related to the study of the very big:
Ben Gamari (undergraduate, now grad school at Umass Amherst)
Rina Takashima (undergraduate, exchange student from Japan)
Shiva Kambhampati (undergraduate, Gamow Fellow, Goldwater Scholar, now medical school)
Ryan Kelly (undergraduate, Gamow Fellow, graduate school at U. Michigan, Ann Arbor, now Aerospace engineer)
John Bulava (undergraduate, PhD in lattice QCD from Carnegie-Mellon U., faculty at Trinity College, Dublin, Ireland, and University of Southern Denmark)
Alexandra Valenti (undergraduate, now patent laywer)
Aryan Khojandi (summer student from Thomas Jefferson High School for Science and Technology in Fairfax, Virginia, now at MIT)
chiQCD all-hands-meeting (December 2015)
Group meeting (October 2015)
Michael Lujan's PhD defense on 6 June 2014
Craig Pelissier's PhD defense on 15 June 2012
Here's a group photo from summer 2012 (height-ordered)
Craig's Parke Prize for Excellence in Theoretical Physics, Spring 2012
Tutun Harsono's PhD defense on 18 Nov 2011
Here's a group photo from summer 2010
Lai Wang's PhD defense in summer 2010
Here's a group photo from summer 2009
Lai's Parke Prize for Excellence in Theoretical Physics
Scott's PhD defense in Fall 2009
Leming's PhD defense in July 2004
Xinyu's PhD defense in November 2003
At GW, we collaborate with colleagues from Statistics Department and SEAS.
We are a founding member of IMPACT,
a GW-wide institute for high-performance computing.
We have also established local collaborations with the
TQHN group at University of Maryland.
Nationally, we are part of χQCD based at University of Kentucky, and USQCD.
Internationally, we have collaborations with
Prof. Wenger's group at University of Bern, Switzerland;
Prof. Mathur's group at Tata Institute of India;
Prof. Leinweber's group at University of Adelaide, Australia.
We have access to a variety of high-performance computers to carry out our research projects.
A 160-core CPU cluster (click here) ) funded by U.S. Department of Energy and GW.
A 16-node GPU-based cluster funded by the Columbian College of Arts and Sciences of GW.
A 1334-core Cray XE6 supercomputer named George at IMPACT.
A 1024-core cluster named Pyramid at IMPACT.
A 32-node GPU cluster named Lehman at IMPACT.
Several supercomputers at NERSC (National Energy Research Supercomputing Center),
located at Lawrence Livermore National Laboratory, and sponsored by U.S. Department of Energy,
the 153216-core Cray XE6 named Hopper (1.28 Petaflops/sec peak).
A 112896-core Cray XT5 supercomputer (1.17 Petaflops/sec peak) named Kraken
at Oak Ridge via NICS of the National Science Foundation.