We construct a utility-based model of fluctuations, with nominal rigidities and unemployment, and draw its implications for the unemployment-inflation trade- off and for the conduct of monetary policy. We proceed in two steps. We first leave nominal rigidities aside. We show that, under a...

We develop a utility based model of fluctuations, with nominal rigidities, and unemployment. In doing so, we combine two strands of research: the New Keynesian model with its focus on nominal rigidities, and the Diamond-Mortensen-Pissarides model, with its focus on labor market frictions and...

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...