Production of a gluon with the exchange of three reggeized gluons in the Lipatov effective action approach

In the Regge kinematics the amplitude for gluon production off three scattering centers is found in the Lipatov effective action technique. The vertex for gluon emission with the reggeon splitting in three reggeons is calculated and its transversality is demonstrated. It is shown that in the sum of all contributions terms containing principal value singularities are cancelled and substituted by the standard Feynman poles. These results may be used for calculation of the inclusive cross-section for gluon production on two nucleons in the nucleus.Comment: 22 pages, 9 figures; submitted to Eur.Phys.Jour.

Wage subsidies and international trade: when does policy coordination pay?

National labour market institutions interact across national boundaries when product markets are global. Labour market policies can thus entail spill-overs, a fact widely ignored in the academic literature. This paper studies the effects of wage subsidies in an international duopoly model with unionised labour markets. We document both positive and negative spill-over effects and discuss the benefits and costs from international policy coordination both for the case of symmetric and asymmetric labour market institutions. Our results suggest that institutional differences could sign responsible for the slow speed at which labour market policy coordination has progressed so far

Introduction: Virtue's Reasons

Over the past thirty years or so, virtues and reasons have emerged as two of the most fruitful and important concepts in contemporary moral philosophy. Virtue theory and moral psychology, for instance, are currently two burgeoning areas of philosophical investigation that involve different, but clearly related, focuses on individual agents’ responsiveness to reasons. The virtues themselves are major components of current ethical theories whose approaches to substantive or normative issues remain remarkably divergent in other respects. The virtues are also increasingly important in a variety of new approaches to epistemology. ..

Boundary conditions in the QCD nucleus-nucleus scattering problem

In the framework of the effective field theory for interacting BFKL pomerons, applied to nucleus-nucleus scattering, boundary conditions for the classical field equations are discussed. Correspondence with the QCD diagrams at the boundary rapidities requires pomeron interaction with the participating nuclei to be exponential and non-local. Commonly used 'eikonal' boundary conditions, local and linear in fields, follow in the limit of small QCD pomeron-nucleon coupling. Numerical solution of the classical field equations, which sum all tree diagrams for central gold-gold scattering, demonstrates that corrected boundary conditions lead to substantially different results, as compared to the eikonal conditions studied in earlier publications. A breakdown of projectile-target symmetry for particular solutions discovered earlier in \cite{bom} is found to occur at roughly twice lower rapidity. Most important, due to a high non-linearity of the problem, the found asymmetric solutions are not unique but form a family growing in number with rapidity. The minimal value for the action turns out to be much lower than with the eikonal boundary conditions and saturates at rapidities around 10.Comment: 19 pages, 8 figure

Helioseismic Holography of an Artificial Submerged Sound Speed Perturbation and Implications for the Detection of Pre-Emergence Signatures of Active Regions

We use a publicly available numerical wave-propagation simulation of Hartlep et al. 2011 to test the ability of helioseismic holography to detect signatures of a compact, fully submerged, 5% sound-speed perturbation placed at a depth of 50 Mm within a solar model. We find that helioseismic holography as employed in a nominal "lateral-vantage" or "deep-focus" geometry employing quadrants of an annular pupil is capable of detecting and characterizing the perturbation. A number of tests of the methodology, including the use of a plane-parallel approximation, the definition of travel-time shifts, the use of different phase-speed filters, and changes to the pupils, are also performed. It is found that travel-time shifts made using Gabor-wavelet fitting are essentially identical to those derived from the phase of the Fourier transform of the cross-covariance functions. The errors in travel-time shifts caused by the plane-parallel approximation can be minimized to less than a second for the depths and fields of view considered here. Based on the measured strength of the mean travel-time signal of the perturbation, no substantial improvement in sensitivity is produced by varying the analysis procedure from the nominal methodology in conformance with expectations. The measured travel-time shifts are essentially unchanged by varying the profile of the phase-speed filter or omitting the filter entirely. The method remains maximally sensitive when applied with pupils that are wide quadrants, as opposed to narrower quadrants or with pupils composed of smaller arcs. We discuss the significance of these results for the recent controversy regarding suspected pre-emergence signatures of active regions

Towards strangeness saturation in central heavy-ion collisions at high energies

Analyses of the centrality binned identified hadron multiplicities at SPS and RHIC within the statistical-thermal model point to strangeness saturation with increasing centrality and energy.Comment: 4 pages, 2 figures. Presented at the 16th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions, Nantes, France, 18-24 July, 200