Doubled Conformal Compactification

We use Weyl transformations between the Minkowski spacetime and dS/AdS spacetime to show that one cannot well define the electrodynamics globally on the ordinary conformal compactification of the Minkowski spacetime (or dS/AdS spacetime), where the electromagnetic field has a sign factor (and thus is discountinuous) at the light cone. This problem is intuitively and clearly shown by the Penrose diagrams, from which one may find the remedy without too much difficulty. We use the Minkowski and dS spacetimes together to cover the compactified space, which in fact leads to the doubled conformal compactification. On this doubled conformal compactification, we obtain the globally well-defined electrodynamics.Comment: 14 pages, 4 figure

Minimum wage and export: evidence from Chinese firm-level data

This paper proposes a two-country trade equilibrium model with heterogeneous firms to investigate the influences of minimum wages and productivity on firms' exports. It shows that the influence of minimum wages on firms' exporting probability and foreign sales is negative while that of firms' productivity on their exports is positive. Econometric analysis based on the Annual Survey of Chinese Industrial Firms as well as the data of minimum wages collected ourselves from 1998 to 2007 verifies these predictions. Holding the other variables constant, if minimum wages and their productivity increase by 100%$, then the elasticity of minimum wage on firms' exporting sales is -8.6$ and increases by 1.6%$, respectively.Minimum wage, heterogeneous firm, productivity, export

The Renormalizable Three-Term Polynomial Inflation with Large Tensor-to-Scalar Ratio

We systematically study the renormalizable three-term polynomial inflation in the supersymmetric and non-supersymmetric models. The supersymmetric inflaton potentials can be realized in supergravity theory, and only have two independent parameters. We show that the general renormalizable supergravity model is equivalent to one kind of our supersymmetric models. We find that the spectral index and tensor-to-scalar ratio can be consistent with the Planck and BICEP2 results, but the running of spectral index is always out of the $2\sigma$ range. If we do not consider the BICEP2 experiment, these inflationary models can be highly consistent with the Planck observations and saturate its upper bound on the tensor-to-scalar ratio ($r \le 0.11$). Thus, our models can be tested at the future Planck and QUBIC experiments.Comment: 38 pages, 40 figure