SURA BOT 11/5/02 Lattice QCD Stephen J Wallace

SURA BOT 11/5/02 Lattice

SURA BOT 11/5/02 QCD Q uantum C hromo D ynamics Quarks and Gluons  Nuclear force.  Nuclear Physics Missing link!

SURA BOT 11/5/02 Broad Scientific Goals Solve QCD, the theory of quarks and gluons. Explain the masses of particles: n, p,… Explain confinement of quarks and gluons. Develop the connections of nuclear physics to quarks and gluons?

SURA BOT 11/5/02 Goals for QCD in Nuclear Physics Explain the masses of particles: p, n, N*, mesons & hybrid mesons. Explain how quarks and gluons make up the spin of the nucleon. Explain charge, magnetism and strangeness distributions of the proton and neutron. Explain the 2-nucleon force because it is the “missing link” to nuclear physics.

SURA BOT 11/5/02 Strategies Solve QCD on a lattice in space & time. Use high-performance commodity clusters: well-suited to Lattice QCD (Jlab/MIT and FermiLab) Or use custom chips designed for QCD (QCDOC: Columbia, IBM, Brookhaven Lab). Focus on hadronic physics outcomes that are important to Nuclear Physics. Develop software architecture for QCD.

SURA BOT 11/5/ Understand the structure of nucleons Lattice gauge theory invented First numerical simulations Quenched nucleon GPD’s Nucleon GPD’s in Full QCD Pion form factor in full QCD GPD Measurements at JLAB First data from GeV Tflop-year Nucleon valence quark momentum agrees with experiment First nucleon structure function calculations

SURA BOT 11/5/ Understand Masses of Hybrid Mesons and Confinement Lattice gauge theory invented Hints of a confining potential Quenched Hybrid Spectrum Hybrid Decays Full Hybrid Spectrum Exotic candidate at BNL First data from GeV Tflop-year Lattice Spectrum agrees with Experiment for Conventional Mesons Flux tubes between Heavy Quarks FY03 Clusters 0.5 TFlop/sec FY06 Clusters 8 Tflop/sec 10 2

SURA BOT 11/5/02 Jlab/MIT Collaboration & SURA Lattice Hadron Physics Collaboration MIT- Negele, Pochinsky,Dreher Jlab- Edwards, Richards, Watson UMd- Ji, Wallace UVA- Thacker GWU- Lee UKy- Liu, Dong, Draper FIU- Fiebig, Narayanan Others: Boston, Regina, Caltech, CMU,

SURA BOT 11/5/02 Long-Range Plan for Nuclear Science P_5547_FINAL.pdf “Lattice QCD is crucial for answering fundamental questions in strong-interaction physics, and it is widely recognized that definitive lattice QCD calculations require multi- teraflops resources – resources now available at reasonable cost. …. The nuclear science component of an internationally competitive lattice effort requires dedicated facilities providing sustained performance of 0.5 teraflops by 2002, growing to 15 teraflops by 2005.”

SURA BOT 11/5/02 Robust Competition & U.S. Response Japanese have Earth Simulator (25 Tflops sustained) now! Europeans buying a 5-10 Tflop Lattice machine from IBM/Columbia. DOE Office of Science has formed national advisory committee for Lattice QCD. Current Funding under DOE SciDAC Initiative (Scientific Discovery Through Advanced Computation) and for QCDOC. Ultrascale computing initiative (DOE-SC)

SURA BOT 11/5/02 National Lattice QCD Advisory DOE Office of Science R. Sugar (UCSB) N. Christ (Columbia U.) J. Negele (MIT) P. Lepage (Cornell U.) P. MacKenzie (Fermilab) W. (Chip) Watson (Jlab) C. Rebbi (Boston U.) M. Creutz (Brookhaven) S. Sharpe (U. Washington)

SURA BOT 11/5/02 Computer Hardware Planning 2003: 0.5 Tflop/sec Clusters at Jlab & Fermilab 2003: 1.5 Tflop/sec QCDOC at Columbia/BNL 2003: 5 Tflop/sec QCDOC at BNL 2006: 8 Tflop/sec at BNL, Jlab & Fermilab 2010: 100 Tflop/sec at ?

SURA BOT 11/5/02 Summary Science-driven computation is recognized widely to be important and timely. Lattice QCD is a leading science driven application with clear goals and plans. Experiments + Lattice QCD both are instrumental to achieving science goals of Nuclear Physics. Ultrascale computing is the way to realize definitive Lattice QCD results.