Proton-Deuteron Elastic Scattering from 2.5 to 22.5 MeV

We present the results of a calculation of differential cross sections and polarization observables for proton-deuteron elastic scattering, for proton laboratory energies from 2.5 to 22.5 MeV. The Paris potential parametrisation of the nuclear force is used. As solution method for the charged-composite particle equations the 'screening and renormalisation approach' is adopted which allows to correctly take into account the Coulomb repulsion between the two protons. Comparison is made with the precise experimental data of Sagara et al. [Phys. Rev. C 50, 576 (1994)] and of Sperison et al. [Nucl. Phys. A422, 81 (1984)].Comment: 24 pages, 8 eps figures, uses REVTe

Momentum Space Integral Equations for Three Charged Particles: Diagonal Kernels

It has been a long-standing question whether momentum space integral equations of the Faddeev type are applicable to reactions of three charged particles, in particular above the three-body threshold. For, the presence of long-range Coulomb forces has been thought to give rise to such severe singularities in their kernels that the latter may lack the compactness property known to exist in the case of purely short-range interactions. Employing the rigorously equivalent formulation in terms of an effective-two-body theory we have proved in a preceding paper [Phys. Rev. C {\bf 61}, 064006 (2000)] that, for all energies, the nondiagonal kernels occurring in the integral equations which determine the transition amplitudes for all binary collision processes, possess on and off the energy shell only integrable singularities, provided all three particles have charges of the same sign, i.e., all Coulomb interactions are repulsive. In the present paper we prove that, for particles with charges of equal sign, the diagonal kernels, in contrast, possess one, but only one, nonintegrable singularity. The latter can, however, be isolated explicitly and dealt with in a well-defined manner. Taken together these results imply that modified integral equations can be formulated, with kernels that become compact after a few iterations. This concludes the proof that standard solution methods can be used for the calculation of all binary (i.e., (in-)elastic and rearrangement) amplitudes by means of momentum space integral equations of the effective-two-body type.Comment: 36 pages, 2 figures, accepted for publication in Phys. Rev.

Long-range behavior of the optical potential for the elastic scattering of charged composite particles

The asymptotic behavior of the optical potential, describing elastic scattering of a charged particle $\alpha$ off a bound state of two charged, or one charged and one neutral, particles at small momentum transfer $\Delta_{\alpha}$ or equivalently at large intercluster distance $\rho_{\alpha}$, is investigated within the framework of the exact three-body theory. For the three-charged-particle Green function that occurs in the exact expression for the optical potential, a recently derived expression, which is appropriate for the asymptotic region under consideration, is used. We find that for arbitrary values of the energy parameter the non-static part of the optical potential behaves for $\Delta_{\alpha} \rightarrow 0$ as $C_{1}\Delta_{\alpha} + o\,(\Delta_{\alpha})$. From this we derive for the Fourier transform of its on-shell restriction for $\rho_{\alpha} \rightarrow \infty$ the behavior $-a/2\rho_{\alpha}^4 + o\,(1/\rho_{\alpha}^4)$, i.e., dipole or quadrupole terms do not occur in the coordinate-space asymptotics. This result corroborates the standard one, which is obtained by perturbative methods. The general, energy-dependent expression for the dynamic polarisability $C_{1}$ is derived; on the energy shell it reduces to the conventional polarisability $a$ which is independent of the energy. We emphasize that the present derivation is {\em non-perturbative}, i.e., it does not make use of adiabatic or similar approximations, and is valid for energies {\em below as well as above the three-body dissociation threshold}.Comment: 35 pages, no figures, revte

The Political Economy of Institutions and Corruption in American States.

Theoretically, this paper draws on political agency theory to formulate hypotheses. Empirically, it shows that political institutions have a role in explaining the prevalence of political corruption in American states. In the states, a set of democracies where the rule of law is relatively well established and the confounding effects of differing electoral systems and regimes are absent, institutional variables relating to the openness of the political system inhibit corruption. That is, other things equal, the extent to which aspiring politicians can enter and gain financial backing, and to which voters can focus their votes on policies and thereby hold incumbent politicians accountable for policy outcomes and find substitutes for them if dissatisfied with those outcomes, reduce corruption as a general problem of agency. These institutional effects are estimated in the presence of controls for variables representing other approaches.

Inequality and Corruption: Evidence from US States

High-quality data on state-level inequality and incomes, panel data on corruption convictions, and careful attention to the consequences of including or excluding fixed effects in the panel specification allow us to estimate the impact of income considerations on the decision to undertake corrupt acts. Following efficiency wage arguments, for a given institutional environment the corruptible employee’s or official’s decision to engage in corruption is affected by relative wages and expected tenure in the public sector, the probability of detection, the cost of fines and jail terms, and the degree of inequality, which indicate diminished prospects facing those convicted of corruption. In US states over 25 years we show that inequality and higher government relative wages significantly and robustly produce less corruption. This reverses other findings of a positive association between inequality and corruption, which we show arises from long-run joint causation by unobserved factors.corruption; rent seeking; inequality; Gini coefficient; efficiency wage; public sector wages

Enforcement and Public Corruption: Evidence from US States

We use high-quality panel data on corruption convictions, new panels of assistant U.S. attorneys and relative public sector wages, and careful attention to the consequences of modeling endogeneity to estimate the impact of prosecutorial resources on criminal convictions of those who undertake corrupt acts. Consistent with “system capacity” arguments, we find that greater prosecutor resources result in more convictions for corruption, other things equal. We find more limited, recent evidence for the deterrent effect of increased prosecutions. We control for and confirm in a panel context the effects of many previously identified correlates and causes of corruption. By explicitly determining the allocation of prosecutorial resources endogenously from past corruption convictions and political considerations, we show that this specification leads to larger estimates of the effect of resources on convictions. The results are robust to various ways of measuring the number of convictions as well as to various estimators.corruption; rent seeking; enforcement; efficiency wage; public sector wages; system capacity

The Political Budget Cycle is Where You Can't See It: Transparency and Fiscal Manipulation

We investigate the effects of fiscal transparency and political polarization on the prevalence of electoral cycles in fiscal balance. The recent political economy literature on electoral cycles identifies such cycles mainly in weak and recent democracies. In contrast, we show, conditioning on a new index of institutional fiscal transparency, that electoral cycles in fiscal balance are a feature also of advanced industrialized economies. Using a sample of nineteen OECD countries in the 1990’s, we identify a persistent pattern of electoral cycles in low(er) transparency countries, while no such cycles can be observed in high(er) transparency countries. Furthermore, we find, in accordance with recent theory, that electoral cycles are larger in more politically polarized countries.fiscal transparency; political polarization; fiscal policy; budget deficits; political budget cycles; electoral policy cycles

Political and Judicial Checks on Corruption: Evidence from American State Governments

The paper investigates the effects of checks and balances on corruption. Within a presidential system, effective separation of powers is achieved under divided government, with the executive and legislative branches being controlled by different political parties. When government is unified, no effective separation exists even within a presidential system, but, we argue, can be partially restored by having an accountable judiciary. Our empirical findings show that divided government and elected, rather than appointed, state supreme court judges are associated with lower corruption and, furthermore, that the effect of an accountable judiciary is stronger under unified government, where government cannot control itself. The effect of an accountable judiciary seems to be driven primarily by judges chosen through direct elections, rather than those exposed to a retention vote following appointment.separation of powers; corruption; rent seeking; checks and balances; political institutions; judicial independence; rule of law