Lepton Flavour Violating Decays of Supersymmetric Higgs Bosons

We compute the lepton flavour violating couplings of Higgs bosons in the Minimal Supersymmetric Standard Model, and show that they can induce the decays (h,H,A) --> mu tau at non-negligible rates, for large tan(beta) and sizeable smuon-stau mixing. We also discuss the prospects for detecting such decays at LHC and other colliders, as well as the correlation with other flavour violating processes, such as tau --> mu gamma and tau --> 3 mu.Comment: 13 LaTeX pages, 2 postscript figures, uses epsfig and axodra

Endogenous Market Structures and Labor Market Dynamics

We propose a flexible prices model where endogenous market structures and search and matching frictions in the labor market interact endogenously. The interplay between firms endogenous entry, strategic interactions among producers and labor market frictions represents a strong amplification channel of technology shocks on labor market variables, and helps addressing the unemployment-volatility puzzle. Consistently with U.S. evidence, new firms create a large fraction of new jobs and grow faster than more mature firms, net firms' entry is procyclical and the price mark up is countercyclical.Endogenous Market Structures; Firms' Entry; Search and Matching Frictions

Endogenous Market Structures and Labor Market Dynamics (New version)

We propose a model characterized by strategic interactions among an endogenous number of producers and search and matching frictions in the labor market. In line with U.S. data: (i) new firms account for a relatively small share of overall employment, but they create a relevant fraction of new jobs; (ii) firms’ entry is procyclical; (iii) price mark ups are countercyclical, while aggregate profits are procyclical. In response to a technology shock the labor share decreases on impact and overshoots its long run level. Also the propagation on labor market variables is stronger than in the standard search model. We argue that the countercyclicality of the price mark up is the key mechanism for our results.Endogenous Market Structures, Job Creation, Firms’ Entry, Search and Matching Frictions.

Endogenous Market Structures and Labor Market Dynamics

We propose a flexible prices model where endogenous market structures and search and matching frictions in the labor market interact endogenously. The interplay between firms endogenous entry, strategic interactions among producers and labor market frictions represents a strong amplification channel of technology shocks on labor market variables, and helps addressing the unemployment-volatility puzzle. Consistently with U.S. evidence, new firms create a large fraction of new jobs and grow faster than more mature firms, net firms’ entry is procyclical and the price mark up is countercyclical.Endogenous Market Structures, Firms’ Entry, Search and Matching Frictions

Why open source software can succeed

The paper discusses three key economic problems raised by the emergence and diffusion of Open source software: motivation, coordination, and diffusion under a dominant standard. First, the movement took off through the activity of a software development community that deliberately did not follow profit motivations. Second, a hierarchical coordination emerged without the support of an organization with proprietary rights. Third, Linux and other open source systems diffused in an environment dominated by established proprietary standards, which benefited from significant increasing returns. The paper shows that recent developments in the theory of critical mass in the diffusion of technologies with network externality may help to explain these phenomena.Open Source, Diffusion, Network Externality.