Does related variety matter for creative employment growth?

Little progress has been made in the mitigation of the controversies surrounding creativity and its role for local economic development (FLORIDA, 2002; PECK, 2005). Moreover, creative industries seem to have been denied, so far, a prominent role in the intense debate about the impact of localization or urbanization economies on innovation and growth. Taking departure in the void between these two streams of literature, I deploy the concept of «related variety», as formulated by BOSCHMA (2005) and FRENKEN, VAN OORT and VERBURG (2007), to verify if well-diversified and interdependent creative industries determine more pronounced local creative employment growth. A pooled OLS panel model has been estimated for 73 Italian provinces (2008-2010), using the total amount of creative workers as dependent variable and the variety indexes as main regressors. The results are mostly consistent with the main hypothesis: related variety, in terms of complementarity between sectors, has a positive and significant effect on provincial creative employment growth

Leptogenic Supersymmetry at the LHC

Leptogenic Supersymmetry is a scenario characterized by copious lepton production in cascade decays. Due to the high lepton multiplicity and the lack of significant missing energy, leptogenic supersymmetry provides very clean channels which can be probed already with the early LHC data. Furthermore, the Higgs may be discovered in the h->b bbar mode because the leptons accompanying Higgs production efficiently suppress the background.Comment: 4 pages, 2 figures. Contribution to the proceedings of SUSY 09, Northeastern University, Boston, M

Skew group algebras of Jacobian algebras

For a quiver with potential $(Q,W)$ with an action of a finite cyclic group $G$, we study the skew group algebra $\Lambda G$ of the Jacobian algebra $\Lambda = \mathcal P(Q, W)$. By a result of Reiten and Riedtmann, the quiver $Q_G$ of a basic algebra $\eta( \Lambda G) \eta$ Morita equivalent to $\Lambda G$ is known. Under some assumptions on the action of $G$, we explicitly construct a potential $W_G$ on $Q_G$ such that $\eta(\Lambda G) \eta\cong \mathcal P(Q_G , W_G)$. The original quiver with potential can then be recovered by the skew group algebra construction with a natural action of the dual group of $G$. If $\Lambda$ is self-injective, then $\Lambda G$ is as well, and we investigate this case. Motivated by Herschend and Iyama's characterisation of 2-representation finite algebras, we study how cuts on $(Q,W)$ behave with respect to our construction.Comment: 34 pages, comments welcome. Final version, to appear in Journal of Algebr

On Resonant Leptogenesis

It has been recently shown that the quantum Boltzmann equations may be relevant for the leptogenesis scenario. In particular, they lead to a time-dependent CP asymmetry which depends upon the previous dynamics of the system. This memory effect in the CP asymmetry is particularly important in resonant leptogenesis where the asymmetry is generated by the decays of nearly mass-degenerate right-handed neutrinos. We study the impact of the nontrivial time evolution of the CP asymmetry in resonant leptogenesis, both in the one-flavour case and with flavour effects included. We show that significant qualitative and quantitative differences arise with respect to the case in which the time dependence of the CP asymmetry is neglected.Comment: 16 pages, 7 figures. IOP LaTeX class used. Minor corrections and references added. Matches the version published in JCA

On the Impact of Flavour Oscillations in Leptogenesis

When lepton flavour effects in thermal leptogenesis are active, they introduce important differences with respect to the case in which they are neglected, the so-called one-flavour approximation. We investigate analytically and numerically the transition from the one-flavour to the two-flavour case when the $\tau$-lepton flavour becomes distinguishable from the other two flavours. We study the impact of the oscillations of the asymmetries in lepton flavour space on the final lepton asymmetries, for the hierarchical right-handed neutrino mass spectrum. Flavour oscillations project the lepton state on the flavour basis very efficiently. We conclude that flavour effects are relevant typically for M_1\lsim 10^{12} GeV, where $M_1$ is the mass of the lightest right-handed neutrino.Comment: 24 pages, 9 figures. Minor corrections; version published in JCA

Quantum Boltzmann Equations and Leptogenesis

The closed time-path formalism is a powerful Green's function formulation to describe non-equilibrium phenomena in field theory and it leads to a complete non-equilibrium quantum kinetic theory. We make use of this formalism to write down the set of quantum Boltzmann equations relevant for leptogenesis. They manifest memory effects and off-shell corrections. In particular, memory effects lead to a time-dependent CP asymmetry whose value at a given instant of time depends upon the previous history of the system. This result is particularly relevant when the asymmetry is generated by the decays of nearly mass-degenerate heavy states, as in resonant or soft leptogenesis.Comment: 21 pages, 5 figures. IOP LaTeX class used. Minor corrections and references added. Matches the version published in JCA