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This paper studies the role of endogenous producer entry and product creation for monetary policy analysis and business cycle dynamics in a general equilibrium model with imperfect price adjustment. Optimal monetary policy stabilizes producer prices, but lets the consumer price index vary to accommodate changes in the number of available products. The free(More)
Previously circulated under the title " Business Cycles and Firm Dynamics " and …rst presented in the summer of 2004. For helpful comments, we thank Robert Shimer, two anonymous referees, and participants in many conferences and seminars. We are grateful to and Banque de France for …nancial support through the Chaire Banque de France at the Paris School of(More)
If borrowing capacity of indebted households is tied to the value of their home, house prices should enter a correctly specified aggregate Euler equation for consumption. I develop a simple two-agent, dynamic general equilibrium model in which home (collateral) values affect debt capacity and consumption possibilities for a fraction of the households. I(More)
We study housing and debt in a quantitative general equilibrium model. In the cross-section, the model matches the wealth distribution, the age pro…les of homeownership and mortgage debt, and the frequency of housing adjustment. In the time-series, the model matches the procyclicality and volatility of housing investment, and the procyclicality of mortgage(More)
Cosmology, high-energy physics and astrophysics are converging on the study of large-scale magnetic fields. While the experimental evidence for the existence of large-scale magnetization in galaxies, clusters and superclusters is rather compelling, the origin of the phenomenon remains puzzling especially in light of the most recent observations. The purpose(More)
A large class of string-cosmology backgrounds leads to a spectrum of relic stochastic grav-itational waves, strongly tilted towards high frequencies, and characterized by two basic parameters of the cosmological model. We estimate the required sensitivity for detection of the predicted gravitational radiation and show that a region of our parameter space is(More)
Within a broad class of inflationary models we critically analyse the way initial quantum fluctuations on a new-physics hypersurface (NPH) affect standard predictions for large-scale cosmological perturbations. We find that these so-called transplanckian effects crucially depend on the definition of the " vacuum state " in particular on which Hamiltonian is(More)