We study the optimal monetary policy problem in a New Keynesian economy with a zero lower bound (ZLB) on the nominal interest rate, when the steady state natural rate (r*) becomes permanently negative. We show that the optimal policy aims to approach gradually a new steady state with positive...

Much recent research has focused on the development and analysis of extensions of the New Keynesian framework that model labor market frictions and unemployment explicitly. This chapter describes some of the essential ingredients and properties of those models, and their implications for...