Black holes and stars in Horava-Lifshitz theory with projectability condition

We systematically study spherically symmetric static spacetimes filled with a fluid in the Horava-Lifshitz theory of gravity with the projectability condition, but without the detailed balance. We establish that when the spacetime is spatially Ricci flat the unique vacuum solution is the de Sitter Schwarzshcild solution, while when the spacetime has a nonzero constant curvature, there exist two different vacuum solutions; one is an (Einstein) static universe, and the other is a new spacetime. This latter spacetime is maximally symmetric and not flat. We find all the perfect fluid solutions for such spacetimes, in addition to a class of anisotropic fluid solutions of the spatially Ricci flat spacetimes. To construct spacetimes that represent stars, we investigate junction conditions across the surfaces of stars and obtain the general matching conditions with or without the presence of infinitely thin shells. It is remarkable that, in contrast to general relativity, the radial pressure of a star does not necessarily vanish on its surface even without the presence of a thin shell, due to the presence of high order derivative terms. Applying the junction conditions to our explicit solutions, we show that it is possible to match smoothly these solutions (all with nonzero radial pressures) to vacuum spacetimes without the presence of thin matter shells on the surfaces of stars.Comment: The relations between energy-momentum tensors used in HL theory and GR are considered, and the singular behavior of the trace of extrinsic curvature is presented. References are updated. Version to appear in Physical Reviews D

Gauge Models in D Dimensions

Utilizing the Gauge Framework, software under development at Baylor University, we explicitly construct all layer 1 weakly coupled free fermionic heterotic string (WCFFHS) gauge models up to order 32 in four to ten large spacetime dimensions. These gauge models are well suited to large scale systematic surveys and, while they offer little phenomenologically, are useful for understanding the structure of the WCFFHS region of the string landscape. Herein we present the gauge groups statistics for this swath of the landscape for both supersymmetric and non-supersymmetric models.Comment: arXiv admin note: substantial text overlap with arXiv:1107.575

Money, Imperfect Information and Economic Fluctuations

This paper summarizes the macro-economic and, in particular, monetary and financial market implications of recent developments in the micro-economic theory of imperfect information. These micro-economic models which lead to credit-rationing on the one hand and limitations in the availability of equity type financing on the other can account for a wide range of observed business cycle and monetary phenomena. These include (a) unemployment, (b) the existence of Keynesian-type multiples, (c) the observed lack of production smoothing in response to cyclical fluctuations in demand, (d) the impact of monetary policy on business activity despite the absence of significant changes in real interest rates, and (e) price rigidities which arise from rational firm decisions (not as an a priori assumption).