2,474 research outputs found
Efimov physics in a finite volume
Three bosons with large scattering length show universal properties that do
not depend on the details of the interaction at short distances. In the
three-boson system, these properties include a geometric spectrum of shallow
three-body states called "Efimov states" and log-periodic dependence of
scattering observables on the scattering length. We investigate the
modification of the Efimov states in a finite cubic box and calculate the
dependence of their energies on the box size using effective field theory. We
explicitly verify the renormalization of the effective field theory in the
finite volume.Comment: 9 pages, 3 figures, sign error corrected, numerical results changed,
final versio
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
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
To bind or not to bind: The H-dibaryon in light of chiral effective field theory
We analyse the quark mass dependence of the binding energy of the H-dibaryon
in the framework of chiral effective field theory. We show that the SU(3)
breaking effects induced by the differences of the pertinent two-baryon
thresholds (Lambda-Lambda, Xi-N, Sigma-Sigma) have a very pronounced impact
that need to be incorporated properly in future lattice QCD simulations. We
also point out that if the H-dibaryon is a two-baryon bound state, its dominant
component is Xi-N rather than Lambda-Lambda, which is a consequence of the
approximate SU(3) flavor symmetry of the two-baryon interactions.Comment: 8 pages, 2 figures; Results updated to the new H binding energy
reported by NPLQCD, conclusions remain unchanged, several references adde
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
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
Ground state energy of the interacting Bose gas in two dimensions: an explicit construction
The isotropic scattering phase shift is calculated for non-relativistic
bosons interacting at low energies via an arbitrary finite-range potential in d
spacetime dimensions. Scattering on a (d-1)-dimensional torus is then
considered, and the eigenvalue equation relating the energy levels on the torus
to the scattering phase shift is derived. With this technology in hand, and
focusing on the case of two spatial dimensions, a perturbative expansion is
developed for the ground-state energy of N identical bosons which interact via
an arbitrary finite-range potential in a finite area. The leading non-universal
effects due to range corrections and three-body forces are included. It is then
shown that the thermodynamic limit of the ground-state energy in a finite area
can be taken in closed form to obtain the energy-per-particle in the
low-density expansion, by explicitly summing the parts of the finite-area
energy that diverge with powers of N. The leading and subleading finite-size
corrections to the thermodynamic limit equation-of-state are also computed.
Closed-form results --some well-known, others perhaps not-- for two-dimensional
lattice sums are included in an appendix.Comment: 24 pages, 2 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
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