General Solutions for Multispin Two-Time Correlation and Response Functions in the Glauber-Ising Chain

The kinetic Glauber-Ising spin chain is one of the very few exactly solvable models of non-equilibrium statistical mechanics. Nevertheless, existing solutions do not yield tractable expressions for two-time correlation and response functions of observables involving products of more than one or two spins. We use a new approach to solve explicitly the full hierarchy of differential equations for the correlation and response functions. From this general solution follow closed expressions for arbitrary multispin two-time correlation and response functions, for the case where the system is quenched from equilibrium at T_i > 0 to some arbitrary T >= 0. By way of application, we give the results for two and four-spin two-time correlation and response functions. From the standard mapping, these also imply new exact results for two-time particle correlation and response functions in one-dimensional diffusion limited annihilation.Comment: 35 Pages, 4 Figure

The Svensson versus McCallum and Nelson Controversy Revisited in the BMW Framework

This note shows that the Svensson versus McCallum and Nelson controversy battled in the Federal Reserve Bank of St. Loius Review (September/ October 2005) can be mapped into a static version of a New Keynesian macro model that consists of an IS-equation, a Phillips curve and an inflation targeting central bank (e.g., Bofinger, Mayer, Wollmershäuser, (2006); Walsh (2002)). As a contribution to literature we supplement the controversy by a forceful graphical analysis. The general debate centers on the question by which notion monetary policy should be implemented. The two sides have fundamentally opposite views on this issue. Svensson argues for targeting rules as a notion of optimal monetary policy, whereas McCallum and Nelson promote simple instrument rules. In this note we systematically analyze these two categories of monetary policy rules. In particular we show that the rule discussed by McCallum and Nelson (2005) imposes different degrees of variability on the economy compared to a targeting rule when monetary policy falls prey to measurement error. To our opinion the hybrid Taylor rule developed by McCallum and Nelson contradicts the original idea of simple rules as a heuristic for monetary policy making and should be rebutted for practical reasons

The Stability and Growth Pact Time to Rebuild!

Within this paper we specify a symmetric two country model for the euro area to evaluate monetary and fiscal policy interaction with decentralized fiscal authorities. Obviously this calls for rules which neatly balance the chances and perils. Thereby we show that stringent rules are a prequisitive for a harmonious functioning of a monetary union. Nevertheless given the ability of fiscal policy to effectively stabilize the economic cycle we show that the current rules in reign are of little use. We close the paper by making some suggestions along which the Stability and Growth Pact might be reformed. --Economic and Monetary Union,Fiscal Policy,Fiscal Rules,Stability and Growth Pact

The Svensson versus McCallum and Nelson Controversy Revisited in the BMW Framework

This note shows that the Svensson versus McCallum and Nelson controversy battled in the Federal Reserve Bank of St. Louis Review (September/ October 2005) can be mapped into a static version of a New Keynesian macro model that consists of an IS-equation, a Phillips curve and an inflation targeting central bank (e.g., Bofinger, Mayer, Wollmershäuser, (2006); Walsh (2002)). As a contribution to literature we supplement the controversy by a forceful graphical analysis. The general debate centers on the question by which notion monetary policy should be implemented. The two sides have fundametaly opposite views on this issue. Svensson argues for targeting rules as a notion of optimal monetary policy, whereas McCallum and Nelson promote simple instrument rules. In this note we systematically analyze these two categories of monetary policy rules. In particular we show that the rule discussed by McCallum and Nelson (2005) imposes different degrees of variability on the economy compared to a targeting rule when monetary policy falls prey to measurement error. To our opinion the rule developed by McCallum and Nelson contradicts the original idea of simple rules as a heuristic for monetary policy making and should be rebutted for practical reasons . --inflation targeting,monetary policy rules,New Keynesian macroeconomics,central bank strategies

Monetary and fiscal policy interaction in the Euro area with different assumptions on the Phillips curve

In this paper we carry over a static version of a New Keynesian Macro Model developed in previous papers (see Bofinger, Mayer, and Wollmershäuser 2002) to a monetary union. For a similar approach see (Uhlig 2002). We will show in particular that a harmonious functioning of a monetary union critically depends on the correlation of shocks that hit the currency area. Additionally a high degree of integration in product markets is advantageous for the ECB as it prevents that national real interest rates can drive a wedge between macroeconomic outcomes across member states. In particular small countries are in a vulnerable position exposed to asymmetric shocks and therefore in need for fiscal policy as an independent stabilization agent with room to breath. --Monetary policy,inflation targeting,fiscal policy,policy coordination,free-riding

R&D, Implementation and Stagnation: A Schumpeterian Theory of Convergence Clubs

We construct a Schumpeterian growth theory consistent with the divergence in per-capita income that has occurred between countries since the mid 19th Century, and with the convergence that occurred between the richest countries during the second half of the 20th Century. The theory assumes that technological change underwent a transformation late in the 19th Century, associated with modern R&D labs. Countries sort themselves into three groups. Those in the highest group converge to a steady state where they do leading edge R&D, while those in the intermediate group converge to a steady state where they implement technologies developed elsewhere. Countries in both of these groups grow at the same rate in the long run, as a result of technology transfer, but inequality between them increases during the transition. Countries in the lowest group grow at a slower rate, with relative incomes that fall asymptotically to zero. Once modern R&D has been introduced, a country may have only a finite window of opportunity in which to introduce the institutions that support it.

Activated aging dynamics and negative fluctuation-dissipation ratios

In glassy materials aging proceeds at large times via thermal activation. We show that this can lead to negative dynamical response functions and novel and well-defined violations of the fluctuation-dissipation theorem, in particular, negative fluctuation-dissipation ratios. Our analysis is based on detailed theoretical and numerical results for the activated aging regime of simple kinetically constrained models. The results are relevant to a variety of physical situations such as aging in glass-formers, thermally activated domain growth and granular compaction.Comment: 4 pages, 4 figs; v2 final version (minor modifs) published in Phys. Rev. Let

The BMW model as a static approximation of a foreward-looking New Keynesian macroeconomic model

Over the last decade a new consensus model has emerged in monetary macroeconomics, labelled New Keynesian macroeconomics (Clarida et al., 1999). It consists of three simple building blocs: a forward-looking IS-equation that is derived from the optimization problem of a representative household, a forward-looking Phillips curve that maps the optimal pricing decisions of monopolistically competitive firms facing restrictions on their ability to adjust wages or prices in a flexible manner, and a relationship that describes how monetary policy is conducted. In Bofinger, Mayer and Wollmershäuser (2002a, 2002b) we developed the BMW model which takes this standard dynamic macro model to an intermediate audience in a down-to-earth fashion. This paper presents the linkages between our static BMW approach and a dynamic New Keynesian macro model. --BMW model,New Keynesian macroeconomic model,optimal monetary policy