Nuclear forces on the lattice

Recent studies by the NPLQCD collaboration of hadronic interactions using lattice QCD are reviewed, with an emphasis on a recent calculation of meson-baryon scattering lengths. Ongoing high-statistics calculations of baryon interactions are also reviewed. In particular, new insights into the signal/noise problems that plague correlation functions involving baryons are discussed.Comment: 12 pages, 12 figures, Talk given at 6th International Workshop on Chiral Dynamics, Bern, Switzerland, 6-10 Jul 200

Inviscid Simulations of Interacting Flags and Falling Sheets

We present a fluid dynamics video showing simulations of flexible bodies flapping and falling in an inviscid fluid. Vortex sheets are shed from the trailing edges of the bodies according to the Kutta condition. For interacting flags, a sampling of synchronous and asynchronous states are shown. For falling flexible sheets, the basic behavior is a repeated series of accelerations to a critical speed at which the sheet buckles, and rapidly decelerates, shedding large vortices. Examples of persistent circling, quasi-periodic flapping, and more complex trajectories are shown.Comment: APS DFD Gallery of Fluid Motion 200

New approach to NN with perturbative pions

The current status of effective field theory (EFT) descriptions of nucleon-nucleon (NN) interactions is briefly reviewed, and a new formulation of EFT which treats pion interactions perturbatively is presented. This approach differs from the Kaplan-Savage-Wise (KSW) expansion in that the singular short distance part of the pion tensor interaction is summed to all orders.Comment: 8 pages, 7 figures, Talk given at 6th International Workshop on Chiral Dynamics, Bern, Switzerland, 6-10 Jul 200