Lattice Field Theory: from quarks to atoms

The simple-looking theory of quarks and gluons, QCD,belies the difficulty of using it to predict thep roperties of the hadronic bound states. Numerical simulations of QCD, formulated on a space time lattice, provide a nonperturbative method for computing many quantities. In the first half of my talk, I reviewsome recent innovations which have resulted in much more accurate calculations. I focus on decays and mixing of B mesons, which are important for understanding how quarks change flavor and searching for non-Standard Model physics. The second half of the talk outlines how lattice field theory techniques can be applied to a very different nonperturbative problem: a cold gas of dilute fermionic atoms, in particular the case where the 2-body scattering length has been tuned to +/- infinity. These atomic gases are a good model of neutron matter. I will show exploratory numerical results for the phase transition separating normal and superfluid matter.