Reworking the Tucson-Melbourne Three-Nucleon Potential

We introduce new values of the strength constants (i.e., $a$, $b$, $c$, and $d$ coefficients) of the Tucson-Melbourne (TM) 2$\pi$ exchange three nucleon potential. The new values come from contemporary dispersion relation analyses of meson factory $\pi$N scattering data. We make variational Monte Carlo calculations of the triton with the original and updated three-body forces to study the effects of this update. We remove a short-range -- $\pi$-range part of the potential due to the $c$ coefficient and discuss the effect on the triton binding energy.Comment: 12 pages, to appear in Few-Body System

A Theoretical Examination of Double Jeopardy: Using Theory as a Guide to Concept Analysis

This article is a theoretical examination of the validity of the double jeopardy hypothesis from a number of social psychological perspectives. After a general review of the literature on double jeopardy, section two sets forth some alternative views on minority aging. In section three, four social psychological theories areexplicated in order to ascertain whether they would predict a double jeopardy outcome. In no case does the prediction suggest double jeopardy. Finally, a caveat is noted regarding how researchers define double jeopardy

Benchmark calculations for polarization observables in 3N scattering

High precision benchmark calculations for phase-shifts and mixing parameters as well as observables in elastic neutron-deuteron scattering below the deuteron breakup threshold are presented using a realistic nucleon-nucleon potential. Two totally different methods, one using a variational principle in configuration space and the other solving the Faddeev equations in momentum space are used and compared to each other. The agreement achieved in phase-shifts and mixing parameters as well as in the polarization observables is excellent. The extreme sensitivity of the vector analyzing power Ay to small changes of the phase shifts and mixing parameters is pointed out.Comment: 22 pages, 5 postscript figure

Momentum and Coordinate Space Three-nucleon Potentials

In this paper we give explicit formulae in momentum and coordinate space for the three-nucleon potentials due to $\rho$ and $\pi$ meson exchange, derived from off-mass-shell meson-nucleon scattering amplitudes which are constrained by the symmetries of QCD and by the experimental data. Those potentials have already been applied to nuclear matter calculations. Here we display additional terms which appear to be the most important for nuclear structure. The potentials are decomposed in a way that separates the contributions of different physical mechanisms involved in the meson-nucleon amplitudes. The same type of decomposition is presented for the $\pi - \pi$ TM force: the $\Delta$, the chiral symmetry breaking and the nucleon pair terms are isolated.Comment: LATEX, 33 pages, 3 figures (available as postscript files upon request

Analysis of three-nucleon forces effects in the A=3A=3 system

Using modern nucleon-nucleon interactions in the description of the $A=3,4$ nuclear systems the $\chi^2$ per datum results to be much bigger than one. In particular it is not possible to reproduce the three- and four-nucleon binding energies and the $n-d$ scattering length simultaneously. This is one manifestation of the necessity of including a three-nucleon force in the nuclear Hamiltonian. In this paper we perform an analysis of some, widely used, three-nucleon force models. We analyze their capability to describe the aforementioned quantities and, to improve their description, we propose modifications in the parametrization of the models. The effects of these new parametrization are studied in some polarization observables at low energies.Comment: 10 pages, to be published in Few-Body Systems. Presented at the workshop on "Relativistic Description of Two- and Three-body Systems in Nuclear Physics" ECT* Trento, 19 - 23 October 200

A New Treatment of 2N and 3N Bound States in Three Dimensions

The direct treatment of the Faddeev equation for the three-boson system in 3 dimensions is generalized to nucleons. The one Faddeev equation for identical bosons is replaced by a strictly finite set of coupled equations for scalar functions which depend only on 3 variables. The spin-momentum dependence occurring as scalar products in 2N and 3N forces accompanied by scalar functions is supplemented by a corresponding expansion of the Faddeev amplitudes. After removing the spin degrees of freedom by suitable operations only scalar expressions depending on momenta remain. The corresponding steps are performed for the deuteron leading to two coupled equations.Comment: 19 page

The Effects of Limiting Punitive Damage Awards

In response to concerns that jury awards in tort cases are excessive and unpredictable, nearly every state legislature has enacted some version of tort reform that is intended to curb extravagant damage awards. One of the most important and controversial reforms involves capping (or limiting) the maximum punitive damage award. We conducted a jury analogue study to assess the impact of this reform. In particular, we examined the possibility that capping punitive awards would cause jurors to inflate their compensatory awards to satisfy their desires to punish the defendant, particularly in situations where the defendant’s conduct was highly reprehensible. Relative to a condition in which punitive damages were unlimited, caps on punitive damages did not result in inflation of compensatory awards. However, jurors who had no option to award punitive damages assessed compensatory damages at a significantly higher level than did jurors who had the opportunity to do so. We discuss the policy implications of these findings

Cost-Effectiveness of Complementary Therapies in the United Kingdom—A Systematic Review(†)

Objectives: The aim of this review is to systematically summarize and assess all prospective, controlled, cost-effectiveness studies of complementary therapies carried out in the UK. Data sources: Medline (via PubMed), Embase, CINAHL, Amed (Alternative and Allied Medicine Database, British Library Medical Information Centre), The Cochrane Library, National Health Service Economic Evaluation Database (via Cochrane) and Health Technology Assessments up to October 2005. Review methods: Articles describing prospective, controlled, cost-effectiveness studies of any type of complementary therapy for any medical condition carried out in the UK were included. Data extracted included the main outcomes for health benefit and cost. These data were extracted independently by two authors, described narratively and also presented as a table. Results: Six cost-effectiveness studies of complementary medicine in the UK were identified: four different types of spinal manipulation for back pain, one type of acupuncture for chronic headache and one type of acupuncture for chronic back pain. Four of the six studies compared the complementary therapy with usual conventional treatment in pragmatic, randomized clinical trials without sham or placebo arms. Main outcome measures of effectiveness favored the complementary therapies but in the case of spinal manipulation (four studies) and acupuncture (one study) for back pain, effect sizes were small and of uncertain clinical relevance. The same four studies included a cost-utility analyses in which the incremental cost per quality adjusted life year (QALY) was less than £10 000. The complementary therapy represented an additional health care cost in five of the six studies. Conclusions: Prospective, controlled, cost-effectiveness studies of complementary therapies have been carried out in the UK only for spinal manipulation (four studies) and acupuncture (two studies). The limited data available indicate that the use of these therapies usually represents an additional cost to conventional treatment. Estimates of the incremental cost of achieving improvements in quality of life compare favorably with other treatments approved for use in the National Health Service. Because the specific efficacy of the complementary therapies for these indications remains uncertain, and the studies did not include sham controls, the estimates obtained may represent the cost-effectiveness non-specific effects associated with the complementary therapies

Modern nuclear force predictions for the neutron-deuteron scattering lengths

The nd doublet and quartet scattering lengths have been calculated based on the modern NN and 3N interactions. We also studied the effect of the electromagnetic interactions in the form introduced in AV18. Switching them off for the various nuclear force models leads to shifts of up to +0.04 fm for doublet scattering length, which is significant for present day standards. The electromagnetic effects have also a noticeable effect on quartet scattering length, which otherwise is extremely stable under the exchange of the nuclear forces. For the current nuclear force models there is a strong scatter of the 3H binding energy and the doublet scattering length values around an averaged straight line (Phillips line). This allows to use doublet scattering length and the 3H binding energy as independent low energy observables.Comment: 16 pages, 1 table, 4 ps figure

Triton calculations with π\pi and ρ\rho exchange three-nucleon forces

The Faddeev equations are solved in momentum space for the trinucleon bound state with the new Tucson-Melbourne $\pi$ and $\rho$ exchange three-nucleon potentials. The three-nucleon potentials are combined with a variety of realistic two-nucleon potentials. The dependence of the triton binding energy on the $\pi NN$ cut-off parameter in the three-nucleon potentials is studied and found to be reduced compared to the case with pure $\pi$ exchange. The $\rho$ exchange parts of the three-nucleon potential yield an overall repulsive effect. When the recommended parameters are employed, the calculated triton binding energy turns out to be very close to its experimental value. Expectation values of various components of the three-nucleon potential are given to illustrate their significance for binding.Comment: 17 pages Revtex 3.0, 4 figures. Accepted for publication in Phys. Rev.