Anomalous dimensions and phase transitions in superconductors

The anomalous scaling in the Ginzburg-Landau model for the superconducting phase transition is studied. It is argued that the negative sign of the $\eta$ exponent is a consequence of a special singular behavior in momentum space. The negative sign of $\eta$ comes from the divergence of the critical correlation function at finite distances. This behavior implies the existence of a Lifshitz point in the phase diagram. The anomalous scaling of the vector potential is also discussed. It is shown that the anomalous dimension of the vector potential $\eta_A=4-d$ has important consequences for the critical dynamics in superconductors. The frequency-dependent conductivity is shown to obey the scaling $\sigma(\omega)\sim\xi^{z-2}$. The prediction $z\approx 3.7$ is obtained from existing Monte Carlo data.Comment: RevTex, 20 pages, no figures; small changes; version accepted in PR

Interview with Chris Wickham [Intervista a Chris Wickham]

L’intervista ripercorre la formazione, la carriera accademica, i rapporti con la comunità scientifica internazionale, i principali temi che caratterizzano l’ampia produzione storiografica di Chris Wickham, nonché il suo impegno politico e le sue esperienze nel campo della valutazione della ricerca e dell’editoria scientifica