Chiral Expansion, Renormalization and the Nuclear Force

The renormalization of singular chiral potentials as applied to NN scattering and the structure of the deuteron is discussed. It is shown how zero range theories may be implemented non-perturbatively as constrained from known long range NN forces.Comment: Talk at International IUPAP Conference on Few-Body Problems in Physics (FB18), Santos-Sao Paulo (Brasil), 21-26 August 200

Power Counting and Wilsonian Renormalization in Nuclear Effective Field Theory

Effective field theories are the most general tool for the description of low energy phenomena. They are universal and systematic: they can be formulated for any low energy systems we can think of and offer a clear guide on how to calculate predictions with reliable error estimates, a feature that is called power counting. These properties can be easily understood in Wilsonian renormalization, in which effective field theories are the low energy renormalization group evolution of a more fundamental ---perhaps unknown or unsolvable--- high energy theory. In nuclear physics they provide the possibility of a theoretically sound derivation of nuclear forces without having to solve quantum chromodynamics explicitly. However there is the problem of how to organize calculations within nuclear effective field theory: the traditional knowledge about power counting is perturbative but nuclear physics is not. Yet power counting can be derived in Wilsonian renormalization and there is already a fairly good understanding of how to apply these ideas to non-perturbative phenomena and in particular to nuclear physics. Here we review a few of these ideas, explain power counting in two-nucleon scattering and reactions with external probes and hint at how to extend the present analysis beyond the two-body problem.Comment: Contribution to the IJMPE special issue on "Effective Field Theories in Nuclear Physics". This update includes the corrections and changes of the published versio

Perturbative Renormalizability of Chiral Two Pion Exchange in Nucleon-Nucleon Scattering: P- and D-waves

We study the perturbative renormalizability of chiral two pion exchange in nucleon-nucleon scattering for p- and d-waves within the effective field theory approach. The one pion exchange potential is fully iterated at the leading order in the expansion, a choice generating a consistent and well-defined power counting that we explore in detail. The results show that perturbative chiral two pion exchange reproduces the data up to a center-of-mass momentum of k_cm ~300 MeV at NNLO and that the effective field theory expansion convergences up to k_cm ~ 350 MeV.Comment: 25 pages, 5 figures; final version. Published in Phys. Rev. C84, 064002 (2011

Statistical Nonlinearities in the Business Cycle

Nonlinear, Real Business Cycles, Efficient Method of Moments

Deuteron radial moments for renormalized chiral potentials

We calculate deuteron positive and negative radial moments involving any bilinear function of the deuteron S and D wave functions for renormalized OPE and TPE chiral potentials. The role played by the strong singularities of the potentials at the origin and the short distance insensitivity of the results when the potentials are fully iterated is emphasized as compared to realistic potentials.Comment: 3 pages, 2 figures. Poster presented at 4th International Conference on Quarks and Nuclear Physics (QNP06), Madrid, Spain, 5-10 Jun 200

Financial Choice in a Non-Ricardian Model of Trade

We join the new trade theory with a model of choice between bank and bond financing to show the differential effects of financial policy on the distribution of firm size, welfare, aggregate output, gains from trade, and the real exchange rate in a small open economy. Increasing bank efficiency and reducing bond transaction costs both increase welfare but have opposite effects on the extensive margin of trade, aggregate exports, and the real exchange rate. Increasing the degree of trade openness increases firms’ relative demand for bond versus bank financing. We identify a financial switching channel for gains from trade where increasing access to export markets allows firms to overcome high fixed costs of bond issuance to secure a lower marginal cost of capital.heterogeneity, bank, bond, firm finance, export real exchange rate

Power Counting of Contact-Range Currents in Effective Field Theory

We analyze the power counting of two-body currents in nuclear effective field theories (EFTs). We find that the existence of non-perturbative physics at low energies, which is manifest in the existence of the deuteron and the 1S0 NN virtual bound state, combined with the appearance of singular potentials in versions of nuclear EFT that incorporate chiral symmetry, modifies the renormalization-group flow of the couplings associated with contact operators that involve nucleon-nucleon pairs and external fields. The order of these couplings is thereby enhanced with respect to the naive-dimensional-analysis estimate. Consequently, short-range currents enter at a lower order in the chiral EFT than has been appreciated up until now, and their impact on low-energy observables is concomitantly larger. We illustrate the changes in the power counting with a few low-energy processes involving external probes and the few-nucleon systems, including electron-deuteron elastic scattering and radiative neutron capture by protons.Comment: 5 pages. Minor revisions. Conclusions unchanged. Version to appear in Physical Review Letter

Fishing Location decisions in the Chilean-Transzonal Jack Mackerel Fishery

This study examines factors conditioning the fishing location decisions of the Chilean fleet operating in the South-east Pacific straddling jack mackerel fishery, considering voyage data for the1987-2004 period. As from the early 1990s, this fleet began to move beyond the 200 nm zone, responding to changes in the spatial distribution of the species. It is thought that this change dynamics may have been intensified by the strong 1997-98 El Niño event. The return of distant water-fishing-nation’s fleets to this fishery, as from the year 2000, has increased interest in understanding effects related with this spatial change dynamics. This paper is an econometric analysis of the effect of environmental, regulatory, technological and economic factors on the fishing location decisions of the Chilean fleet working in this fishery. The possible influence of El Niño events on the spatial operations of this fleet is tested.