What has been the tax competition experience of the past 20 years?

This paper describes tax reforms in OECD countries over the last 20 years and how they are related to tax competition. Both individual countries? reforms and multilateralinitiatives and developments are covered. This is followed by an overview of theempirical evidence on tax competition. Our conclusion is that the evidence for someinterdependence in tax setting behaviour is strong, although the exact process driving thisremains unclear. While the most basic tax competition models fail to explain thedevelopment in OECD countries, there is more than one possible explanation for thereforms undertaken if more advanced models are considered. The multilateral initiativesthat were implemented however do not seem to be related to resource-based taxcompetition, instead they are about taxing rights. This paper describes tax reforms in OECD countries over the last 20 years and how they are related to tax competition. Both individual countries? reforms and multilateralinitiatives and developments are covered. This is followed by an overview of theempirical evidence on tax competition. Our conclusion is that the evidence for someinterdependence in tax setting behaviour is strong, although the exact process driving thisremains unclear. While the most basic tax competition models fail to explain thedevelopment in OECD countries, there is more than one possible explanation for thereforms undertaken if more advanced models are considered. The multilateral initiativesthat were implemented however do not seem to be related to resource-based taxcompetition, instead they are about taxing rights

Theory of Coherent cc-Axis Josephson Tunneling between Layered Superconductors

We calculate exactly the Josephson current for $c$-axis coherent tunneling between two layered superconductors, each with internal coherent tight-binding intra- and interlayer quasiparticle dispersions. Our results also apply when one or both of the superconductors is a bulk material, and include the usually neglected effects of surface states. For weak tunneling, our results reduce to our previous results derived using the tunneling Hamiltonian. Our results are also correct for strong tunneling. However, the $c$-axis tunneling results of Tanaka and Kashiwaya are shown to be incorrect in any limit. In addition, we consider the $c$-axis coherent critical current between two identical layered superconductors twisted an angle $\phi_0$ about the $c$-axis with respect to each other. Regardless of the order parameter symmetry, our coherent tunneling results using a tight-binding intralayer quasiparticle dispersion are inconsistent with the recent $c$-axis twist bicrystal Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ twist junction experiments of Li {\it et al.}Comment: 11 pages, 13 figures, submitted to Physical Review

The timelike half-supersymmetric backgrounds of N=2, D=4 supergravity with Fayet-Iliopoulos gauging

Subject to some relatively mild assumptions, we derive the complete form of all timelike half-supersymmetric solutions to N=2, D=4 gauged supergravity coupled to an arbitrary number of abelian vector multiplets. This is done using spinorial geometry techniques. Explicit examples are given for a simple prepotential. Among the solutions, there are near-horizon geometries of extremal rotating BPS black holes still to be discovered, with a nontrivial dependence of the scalar fields on one of the horizon coordinates.Comment: 38 pages, uses JHEP3.cl

Issues in the design and implentation of an R&D tax credit for the UK

R&D tax credits have become a popular policy tool for encouraging research and development (R&D) spending by business, with many countries offering subsidies of this form. The divergence between private and social rates of return to R&D expenditure by private firms provides one of the main justifications for government subsidies to R&D.2 In order to achieve the optimal level of R&D investment, government policy aims to bring private incentives in line with the social rate of return. An R&D tax credit does this by reducing the cost to the firm of doing R&D. Recent empirical evidence suggests that R&D tax credits are an effective instrument in stimulating additional R&D. However, in order to be desirable, a policy needs to be cost-effective and implementable. This Briefing Note reviews some of the major issues in the design and implementation of R&D tax credits. In Section 2, we briefly discuss the existing tax treatment of R&D in the UK. In particular, we outline the new Research and Development Allowance - which is an allowance for expenditure on plant, machinery and buildings for use in scientific research and which is available to firms of all sizes - and the tax credit for R&D that is available to small and medium-sized enterprises (SMEs). We then discuss, in Section 3, some of the main design features of tax credits that have been implemented in other countries. The discussion mainly concerns the question of how to target new or incremental R&D so as to keep down the total exchequer cost. We discuss problems that arise in defining incremental R&D and how these can be tackled. In Section 4, we provide estimates of the amount of new R&D and the exchequer cost that would be likely to result from implementing different designs of R&D tax credit in the UK. Section 5 concludes. Some technical details are dealt with in the Appendix

How has the UK corporation tax raised so much revenue?

We analyse a puzzle in the UK corporation tax: by both historic and international standards corporation tax revenues have been high while the statutory rate has been low. Possible explanations include the following: changes in tax law that may have increased effective tax rates; other factors such as higher profitability or different macro-economic conditions may have led to higher effective tax rates; and finally the size of the corporate sector may have increased. We find evidence for all three explanations, although none would be sufficient in itself. To the extent that higher profits, particularly financial sector profits may have led to high revenues, there are doubts as to whether revenues will continue to be so strong

Absolute rate parameters for the reaction of ground state atomic oxygen with carbonyl sulfide

The rate parameters for the reaction of O(3P) with carbonyl sulfide, O(3P) + OCS yields CO + SO have been determined directly by monitoring O(3P) using the flash photolysis-resonance fluorescence technique. The value for k sub 1 was measured over a temperature range of 263 - 502 K and the data were fitted to an Arrhenuis expression with good linearity

Holomorphic Anomaly in Gauge Theories and Matrix Models

We use the holomorphic anomaly equation to solve the gravitational corrections to Seiberg-Witten theory and a two-cut matrix model, which is related by the Dijkgraaf-Vafa conjecture to the topological B-model on a local Calabi-Yau manifold. In both cases we construct propagators that give a recursive solution in the genus modulo a holomorphic ambiguity. In the case of Seiberg-Witten theory the gravitational corrections can be expressed in closed form as quasimodular functions of Gamma(2). In the matrix model we fix the holomorphic ambiguity up to genus two. The latter result establishes the Dijkgraaf-Vafa conjecture at that genus and yields a new method for solving the matrix model at fixed genus in closed form in terms of generalized hypergeometric functions.Comment: 34 pages, 2 eps figures, expansion at the monopole point corrected and interpreted, and references adde

Epidemic threshold in structured scale-free networks

We analyze the spreading of viruses in scale-free networks with high clustering and degree correlations, as found in the Internet graph. For the Suscetible-Infected-Susceptible model of epidemics the prevalence undergoes a phase transition at a finite threshold of the transmission probability. Comparing with the absence of a finite threshold in networks with purely random wiring, our result suggests that high clustering and degree correlations protect scale-free networks against the spreading of viruses. We introduce and verify a quantitative description of the epidemic threshold based on the connectivity of the neighborhoods of the hubs.Comment: 4 pages, 4 figure