Relativistic quantum dynamics of scalar bosons under a full vector Coulomb interaction

The relativistic quantum dynamics of scalar bosons in the background of a full vector coupling (minimal plus nonminimal vector couplings) is explored in the context of the Duffin-Kemmer-Petiau formalism. The Coulomb phase shift is determined for a general mixing of couplings and it is shown that the space component of the nonminimal coupling is a {\it sine qua non} condition for the exact closed-form scattering amplitude. It follows that the Rutherford cross section vanishes in the absence of the time component of the minimal coupling. Bound-state solutions obtained from the poles of the partial scattering amplitude show that the time component of the minimal coupling plays an essential role. The bound-state solutions depend on the nonminimal coupling and the spectrum consists of particles or antiparticles depending on the sign of the time component of the minimal coupling without chance for pair production even in the presence of strong couplings. It is also shown that an accidental degeneracy appears for a particular mixing of couplings.Comment: 8 pages, 1 table. arXiv admin note: text overlap with arXiv:1403.603

Gravitational Wave Signatures of Highly Magnetized Neutron Stars

Motivated by the recent gravitational wave detection by the LIGO-VIRGO observatories, we study the Love number and dimensionless tidal polarizability of highly magnetized stars. We also investigate the fundamental quasi-normal mode of neutron stars subject to high magnetic fields. To perform our calculations we use the chaotic field approximation and consider both nucleonic and hyperonic stars. As far as the fundamental mode is concerned, we conclude that the role played by the constitution of the stars is far more relevant than the intensity of the magnetic field and if massive stars are considered, the ones constituted by nucleons only present frequencies somewhat lower than the ones with hyperonic cores, a feature that can be used to point out the real internal structure of neutron stars. Moreover, our studies clearly indicate that strong magnetic fields play a crucial role in the deformability of low mass neutron stars, with possible consequences on the interpretation of the detected gravitational waves signatures.Comment: 24 pages, 4 figures, 6 table

A Configurational Approach to Comparative Corporate Governance

We seek to bring to the core of the study of comparative corporate governance analysis the idea that within countries and industries, there exist multiple configurations of firm level characteristics and governance practices leading to effective corporate governance. In particular, we propose that configurations composed of different bundles of corporate governance practices are a useful tool to examine corporate governance models across and within countries (as well as potentially to analyze over time changes). While comparative research, identifying stylized national models of corporate governance, has been fruitful to help us think about the key institutional and shareholder rights determining governance differences and similarities across countries, we believe that given the financialization of the corporate economy, current globalization trends of investment, and rapid information technology advances, it is important to shift our conceptualization of governance models beyond the dichotomous world of common-law/outsider/shareholder-oriented system vs. civil law/insider/stakeholder oriented system. Our claim is based on the empirical observation that there exists a wide range of firms that either (1) fall in the "wrong" corporate governance category; (2) are a hybrid of these two categories; or (3) should be placed into an entirely new category such as firms in emerging markets or state-owned firms. In addition, as Aguilera and Jackson (2003) argue, firms, regardless of their legal family constraints, their labor and product markets, and the development of the financial markets from which they can draw, have significant degrees of freedom to chose whether to implement different levels of a given corporate governance practice. That is, firms might chose to fully endorse a practice or simply seek to comply with the minimum requirements without truly internalizing the governance practice. An illustrative example of the different degrees of internalization of governance practices is the existing variation in firms' definition of director independence or disclosure of compensation systems. We first discuss the conceptual idea of configurations or bundles of corporate governance practices underscoring the concept of equifinal paths to given firm outcomes as well as the complementarity and substitution in governance practices. We then move to the practice level of analysis to show how three governance characteristics (legal systems, ownership and boards of directors) cannot be conceptualized independently, as each of them is contingent on the strength and prevalence of other governance practices. In the last section, we illustrate how different configurations are likely to playout across industries and countries, taking as the departing practice, corporate ownership.

Relative returns to policy reform - evidence from controlled cross-country regressions

The authors aim at contributing to understand the dispersion of returns from policy reforms using cross-country regressions. The authors compare the"before reform"with"after reform"GDP growth outcome of countries that undertook import-liberalization and fiscal policy reforms. They survey a large sample (about 54) of developing countries over the period 1980-99. The benefits of openness to trade and fiscal prudence have been extensively identified in the growth literature, but the evidence from simple cross-section analysis can sometimes be inconclusive and remains vulnerable to criticism on estimation techniques, such as identification, endogeneity, multi-colinearity, and the quality of the data. The authors use a different analytical framework that establishes additional controls. First, they construct a counterfactual control group. These are countries that-under specific thresholds-did not introduce policy reforms under scrutiny. Second, the authors also try to use the most appropriate variable of policy reform, for example, exogenous changes in import-tariffs instead of the endogenous sum of all trade flows. Third, the authors try to base the before-after reform comparison on the most accurate date for the beginning of a policy reform period (instead of comparing averages over fixed intervals of time). Once these controls are set, they explain the difference between average GDP growth rates during the country-specific post and the pre-reform periods, relative to the average GDP growth of the relevant control group. The explanatory variables in the regressions include the standard growth-regression controls. The results are the following: 1) With a better measurement and timing of the policy reforms, the growth effect (the"returns on reform") is generally smaller than in previous papers. 2) There is evidence of contingent relationships between policy and growth, corresponding to the country's size, its export profile, and its governance. 2) Within the group of policy reformers, some countries have exhibited a relatively weaker growth response. Overall, the findings suggest that more accurate measurement and definition of the timing of reforms does not strengthen the significance of the effects of reforms on GDP growth. In fact, the effects are weaker than indicated in most cross-section studies. This suggests that the policy implications to be derived from these relationships should be treated with even more caution than previously thought.Environmental Economics&Policies,Trade Policy,Public Health Promotion,Economic Theory&Research,Health Monitoring&Evaluation,TF054105-DONOR FUNDED OPERATION ADMINISTRATION FEE INCOME AND EXPENSE ACCOUNT,Economic Theory&Research,Achieving Shared Growth,Environmental Economics&Policies,Trade and Regional Integration

Abandonada

Senior Project submitted to The Divisions of Arts of Bard Colleg