Quasielastic K+ scattering in nuclei

The quasielastic scattering kaon-nucleus experiment performed at BNL is analyzed in a finite nucleus continuum random phase approximation framework, treating the reaction mechanism in Glauber theory up to two-step inelastic processes. A good description of the data is achieved, also providing a useful constraint on the strength of the effective particle-hole interaction in the scalar-isoscalar channel at intermediate momentum transfers.Comment: 4 pages, 3 figures, needs espcrc1 and epsfig; presented at the International Conference on Hypernuclear and Strange Particle Physics, BNL October 13-18, 199

Grid-Bootstrap Methods vs. Bayesian Analysis. Testing for Structural Breaks in the Conditional Variance of Nominal Interest Rate Spreads - Four Cases in Europe

I use numerical methods to test for the presence of one-time structural breaks in the conditional variance of nominal interest rate spreads in four European countries over a period of eleven years (Jan 1988 to Dec 1998). I start with an intuitive approach consisting of a sequence of breakpoint Chow tests performed at subsequent dates over a given subsample of the squared residuals of the autoregressions used to model the yield spreads. Results from this procedure are misleading and spurious to some extent because of the incorrect critical values produced, which make the interpretation of the test stastistics basically unreliable. I then switch to large Monte Carlo simulations and to a fixed-regressor grid-bootstrap method to derive the right critical values and refine the previous conclusions. Finally, I utilize classical Bayesian econometrics to estimate alternative models for the series of nominal spreads and to detect potential shifts in the innovation variances of the equations describing the data. Outcomes need some interpretation: in the cases of Germany and Spain a break might have occurred in 1990 and 1994 respectively, as derived from the grid bootstrap approach. Likewise, there is evidence of a shift in the case of France in 1996 according to the Bayesian techniques employed, which also validate the hypothesis of a break for Italian yield spreads in 1995.Chow Test; Classical Bayesian Analysis; Conditional Variance; Fixed-Regressor Grid-Bootstrap Method; Structural Breaks.

Nuclear response functions with finite range Gogny force: tensor terms and instabilities

A fully-antisymmetrized random phase approximation calculation employing the continued fraction technique is performed to study nuclear matter response functions with the finite range Gogny force. The most commonly used parameter sets of this force, as well as some recent generalizations that include the tensor terms are considered and the corresponding response functions are shown. The calculations are performed at the first and second order in the continued fraction expansion and the explicit expressions for the second order tensor contributions are given. Comparison between first and second order continued fraction expansion results are provided. The differences between the responses obtained at the two orders turn to be more pronounced for the forces including tensor terms than for the standard Gogny ones. In the vector channels the responses calculated with Gogny forces including tensor terms are characterized by a large heterogeneity, reflecting the different choices for the tensor part of the interaction. For sake of comparison the response functions obtained considering a G-matrix based nuclear interaction are also shown. As first application of the present calculation, the possible existence of spurious finite-size instabilities of the Gogny forces with or without tensor terms has been investigated. The positive conclusion is that all the Gogny forces, but the GT2 one, are free of spurious finite-size instabilities. In perspective, the tool developed in the present paper can be inserted in the fitting procedure to construct new Gogny-type forces

Randomness in nuclei and in the quark-gluon plasma

The issue of averaging randomness is addressed, mostly in nuclear physics, but shortly also in QCD. The Feshbach approach, so successful in dealing with the continuum spectrum of the atomic nuclei ("optical model"), is extended to encompass bound states as well ("shell model"). Its relationship with the random-matrix theory is discussed and the bearing of the latter on QCD, especially in connection with the spectrum of the Dirac operator, is briefly touched upon. Finally the question of whether Feshbach's theory can cope with the averaging required by QCD is considered.Comment: 24 pages, 6 figures; to appear in the Proceedings of the Workshop "Quark-Gluon Plasma and Relativistic Heavy Ions", Frascati, 14-18 January 200

Statistical theory of the many-body nuclear system

A recently proposed statistical theory of the mean fields associated with the ground and excited collective states of a generic many-body system is extended by increasing the dimensions of the P-space. In applying the new framework to nuclear matter, in addition to the mean field energies we obtain their fluctuations as well, together with the ones of the wavefunctions, in first order of the expansion in the complexity of the Q-space states. The physics described by the latter is assumed to be random. To extract numerical predictions out of our scheme we develop a schematic version of the approach, which, while much simplified, yields results of significance on the size of the error affecting the mean fields, on the magnitude of the residual effective interaction, on the ground state spectroscopic factor and on the mixing occurring between the vectors spanning the P-space.Comment: 27 pages, 3 figures; Dedicated to the memory of Herman Feshbac

The (non-)resiliency of foreign direct investment in the United States during the 2007-2009 financial crisis

We study the contraction of Foreign Direct Investment (FDI) flows in the United States during the recent financial crisis and show their unusual non-resiliency, which depends in part on the global nature of the economic recession, but also on the increases in the cost of financing FDI in the economies in which the flows originate. To formally study the effects of external financial conditions on FDI in the United States, we exploit the three dimensions of a panel of U.S. inward FDI flows organized by recipient U.S. industries, source countries, and years for the recorded flows. Changes in the cost of finance in the source countries have little or no effect on total inward flows (the sum of equity, debt, and reinvested earnings) over the 2006-2010 period. However, U.S. industries characterized by more financial vulnerability experience statistically significant variations in the debt and equity components of inward FDI flows in response to the changes in the cost of capital that occurred in the source countries during the crisis.Capital movements ; Financial crises ; Investments, Foreign

Light-front quark distributions in the nucleon and nucleon electromagnetic form factors

Longitudinal and transverse quark momentum distributions in the nucleon are calculated from a phenomenological quark-nucleon vertex function obtained through an investigation of the nucleon electromagnetic form factors within a light-front framework.Comment: 6 pages, 11 figs. proceedings of LC2009, to appear in Nucl. Phys.