The Lattice Group includes members of three collaborations:

NPLQCD, HotQCD, and Lattice Strong Dynamics.

Our ultimate goal is to calculate the structure and interactions of the lightest nuclei from QCD. Not only would this allow for the calculation of nuclear processes in situations where experiments to guide phenomenological calculations are not possible, but it would also provide a complete determination of how these processes depend upon the fundamental constants of nature: the quark masses, the scale of the strong interaction, and the electroweak interactions.

Understanding how to extract this information from lattice calculations in Euclidean space is key to accomplishing this goal with lattice QCD. The Maiani-Testa theorem states that infinite-volume Euclidean space Green functions cannot be used to extract S-matrix elements except at kinematic thresholds. Fortunately, by measuring the energy of two-particle states at finite-volume the two-particle scattering amplitude can be extracted (at that energy). We are currently employing this method to study the scattering lengths of nucleon-nucleon, nucleon-hyperon, hyperon-hyperon, meson-nucleon, and meson-meson interactions.

Primary topics of the HotQCD Collaboration include calculations of the location and nature of the chiral and deconfinement transition temperatures, and the QCD equation of state. The collaboration calculates thermodynamic observables such as the chiral condensate, chiral susceptibilities, and quark number susceptibilities which are directly related to charge and isospin fluctuations in heavy ion collisions. All calculations are performed with near physical quark masses and close to the continuum.

The HotQCD Collaboration was formed in 2007 to optimize the use of the LLNL BG/L supercomputer for lattice gauge calculations in QCD thermodynamics with an emphasis on calculations that pertain to experimental data from heavy ion collisions. HotQCD also performs calculations on computing resources managed and allocated by USQCD, as well as institutional resources at BNL (NYBlue) and elsewhere. Members of HotQCD include lattice groups at BNL, LANL, LLNL, UCSB, Columbia University, University of Arizona, Indiana University, and University of Utah.

The Lattice Strong Dynamics (LSD) collaboration was formed in 2008 to utilize the sizable LLNL computational resources to address pressing questions in beyond the Standard Model (BSM) physics. This collaboration also receives computational resource allocations from USQCD and XSEDE (formerly Teragrid) to address the computationally demanding problems that strongly coupled models of BSM physics present.

The group's primary focus to date has been exploring physics in QCD-like models with different numbers of techni-fermion flavors (two, six, ten), with an emphasis on quantities such as the spectrum, chiral condensate, S parameter, and WW scattering. Future directions include expanding the exploration of theory space by changing the number of colors and flavors modeled and exploring additional phenomenologically relevant quantities for high energy experiments.