### Session R9: Lattice QCD in Elementary Particle Physics

Sponsoring Units: DCOMP
Chair: Steven Gottlieb, Indiana University
Room: Hyatt Regency St. Louis Riverfront (formerly Adam's Mark Hotel), Promenade E

 Monday, April 14, 2008 10:45AM - 11:21AM R9.00001: Simulations of QCD with Staggered Quarks: Results and Issues Invited Speaker: Claude Bernard I describe recent advances in simulating QCD using the staggered quark action. Current results from the MILC collaboration on the physics of light pseudoscalars (pion and kaon decay constants, $V_{us}$, quark masses, and low energy constants) are presented, as are results from the Fermilab/MILC collaboration on leptonic decay constants and semileptonic form factors of the B and D systems. In addition, I detail the progress that has recently been made in putting staggered QCD simulations on a firmer theoretical footing, in particular by understanding the so-called rooting trick'' and the corresponding chiral effective theory. Monday, April 14, 2008 11:21AM - 11:57AM R9.00002: Testing the Standard Model in the quark flavor sector using lattice QCD Invited Speaker: Ruth Van de Water Recent advances in both computers and algorithms now allow realistic calculations of Quantum Chromodynamics (QCD) interactions using the numerical technique of lattice QCD. The methods used in so-called 2+1 flavor" lattice calculations have been verified both by post-dictions of quantities that were already experimentally well- known and by predictions that occurred before the relevant experimental determinations were sufficiently precise. This suggests that the sources of systematic error in lattice calculations are under control, and that lattice QCD can now be reliably used to calculate those weak matrix elements that cannot be measured experimentally but are necessary to interpret the results of many high-energy physics experiments. These same calculations also allow stringent tests of the Standard Model of particle physics, and may therefore lead to the discovery of new physics in the future. Monday, April 14, 2008 11:57AM - 12:33PM R9.00003: The removal of critical slowing down in lattice QCD Invited Speaker: Michael Clark The quark mass dependence of the computational cost in lattice QCD has proven to be a major obstacle against realistic calculation. I present recent progress in this area, specifically, a new multigrid algorithm which essentially removes this mass dependence.