Pourquoi les frictions nominales amplifient-elles les fluctuations du chômage ?

In this article we study the consequences of the presence of nominal frictions in a general equilibrium search and matching model. The presence of nominal frictions, in line with the New Keynesian framework, implies that in the short run firms choose to decrease labor, since demand doesn?t react to a positive productivity shock because of price rigidities. In the medium run, as prices adjust, the functioning of the economy comes back to the one highlighted in the real business cycle literature : a positive productivity shock decreases unemployment. We claim that this non monotonic dynamics of labor market variables, together with a calibration strategy in line with general equilibrium models, allows us to contribute to solve the ?puzzles? considered by Shimer [2005] : the relative volatilities of labor market variables, as well as their correlations with productivity implied by our calibrated version of the model are in line with the data for the United States.