Phase separation in asymmetrical fermion superfluids

Motivated by recent developments on cold atom traps and high density QCD we consider fermionic systems composed of two particle species with different densities. We argue that a mixed phase composed of normal and superfluid components is the energetically favored ground state. We suggest how this phase separation can be used as a probe of fermion superfluidity in atomic traps.Comment: 9 pages, LaTeX2e, version to appear in Phys.Rev.Let

Superfluid phases of the three-species fermion gas

We discuss the zero temperature phase diagram of a dilute gas with three fermionic species. We make use of solvable limits to conjecture the behavior of the system in the "unitary" regions. The physics of the Thomas-Efimov effect plays a role in these considerations. We find a rich phase diagram with superfluid, gapless superfluid and inhomogeneous phases with different symmetry breaking patterns. We then discuss one particular possible experimental implementation in a system of ^6Li atoms and the possible phases arising in this system as an external magnetic field is varied across three overlaping Feshbach resonances. We also suggest how to experimentally distinguish the different phases.Comment: 4 pages, 1 figure, typos corrected and references adde

Renormalization of the Three-Body System with Short-Range Interactions

We discuss renormalization of the non-relativistic three-body problem with short-range forces. The problem becomes non-perturbative at momenta of the order of the inverse of the two-body scattering length, and an infinite number of graphs must be summed. This summation leads to a cutoff dependence that does not appear in any order in perturbation theory. We argue that this cutoff dependence can be absorbed in a single three-body counterterm and compute the running of the three-body force with the cutoff. We comment on relevance of this result for the effective field theory program in nuclear and molecular physics.Comment: 5 pages, RevTex, 4 PS figures included with epsf.sty, some clarifying comments added, version to appear in Phys. Rev. Let

Nucleon-Nucleon Scattering From Fully-Dynamical Lattice QCD

We present results of the first fully-dynamical lattice QCD determination of nucleon-nucleon scattering lengths in the 1S0 channel and 3S1-3D1 coupled channels. The calculations are performed with domain-wall valence quarks on the MILC staggered configurations with lattice spacing of b=0.125 fm in the isospin-symmetric limit, and in the absence of electromagnetic interactions.Comment: 4 pages, 4 figure

How To Classify 3-Body Forces -- And Why

For systems with only short-range forces and shallow 2-body bound states, the typical strength of any 3-body force in all partial-waves, including external currents, is systematically estimated by renormalisation-group arguments in the Effective Field Theory of Point-Like Interactions. The underlying principle and some consequences in particular in Nuclear Physics are discussed.Comment: 7 pages LaTeX2e using FBSart-class (provided); 2 figures in 3 .eps files included using graphicx; to appear in Few-Body System