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

The Lambda_Q-Lambda_Q Potential

Lattice QCD simulations of the potential between two baryons, each containing a heavy quark and two light quarks, such as the Lambda_Q-Lambda_Q potential, will provide insight into the nucleon-nucleon interaction. As one-pion exchange does not contribute to the Lambda_Q-Lambda_Q potential, the long-distance behavior is dominated by physics that contributes to the intermediate-range attraction between two nucleons. We compute the leading long-distance contributions to the Lambda_Q-Lambda_Q potential in QCD and in partially-quenched QCD in the low-energy effective field theory.Comment: 10 pages LaTeX, 3 eps figs, 3 ps fig

Exploring Baryon Chiral Multiplets

The full QCD chiral symmetry algebra has predictive consequences at low energies. I discuss the ground-state chiral multiplet involving the light baryons and emphasize the special role of the Roper resonance.Comment: 10 pages. Invited plenary talk at NSTAR 2002, Pittsburgh, PA, 9-12 October 200

Restless pions: orbifold boundary conditions and noise suppression in lattice QCD

The study of one or more baryons in lattice QCD is severely hindered by the exponential decay in time of the signal-to-noise ratio. The rate at which the signal-to-noise decreases is a function of the the pion mass. More precisely, it depends on the minimum allowed pion energy in the box, which, for periodic boundary conditions, is equal to its mass. We propose a set of boundary conditions, given by a "parity orbifold'' construction, which eliminates the zero momentum pion modes, raising the minimum pion energy without altering the QCD ground state, and thereby improving the signal-to-noise ratio of (multi)-baryon correlation functions at long Euclidean times. We discuss variations of these "restless pions" boundary conditions and focus on their impact on the study of nuclear forces.Comment: 15 pages, 4 figure

Nucleon-Nucleon Scattering in the 1/N Expansion

The nucleon-nucleon 3S1-3D1 coupled-channel problem is solved analytically to leading order in a joint expansion in the quark masses and in 1/N. An approximate expression is derived for the 3S1 scattering length in the large-N limit, and the large-N behavior of the deuteron is discussed.Comment: 10 pages, Invited talk, The Phenomenology of Large-N_c QCD, to be published Proceedings of the Institute of Nuclear Theor

Unification of the physics of nucleons and nuclei

I outline an ambitious program which aims to achieve a unified description of nucleon and nuclear properties based on one chiral effective field theory.Comment: 9 pp, 6 figs, plenary talk at 17th International IUPAP Conference on Few-body Problems in Physics, June 5-10, 2003, Durham, North Carolina, US

Status of Effective Field Theory of NN Scattering

I review recent progress in developing a systematic power counting scheme for scattering processes involving more than one nucleon.Comment: 9 pages LaTeX and appb.sty, 2 figures (uses epsf); Talk given at the Workshop on 'The Structure of Mesons, Baryons and Nuclei', Cracow, May 1998, in honor of J. Speth's 60th birthday, to be published in Acta Physica Polonica

Baryons in Partially-Quenched Chiral Perturbation Theory

I discuss the inclusion of baryons into partially-quenched chiral perturbation theory and describe one-loop calculations that have been performed.Comment: Lattice2002(matrixel) : talk presented at Lattice 2002, 7 page