Effective Theories in Modern Physics Group

Hadronic Physics

Finite temperature and density

We are interested in light meson systems at finite temperature and nuclear density, such as those formed in Relativistic Heavy Ion Collisions and cold nuclear matter. Within the framework of Unitarized Chiral Perturbation Theory, we are currently investigating transport properties, thermal resonances, chemical nonequilibrium effects, isospin breaking, higher order condensates and chiral susceptibilities. Our results for transport coefficients are obtained within a diagrammatic approach and show similar features as calculations based on kinetic theory, also performed by members of our group. Shear viscosity over entropy is very smooth near the transition, whereas bulk viscosity is highly correlated with the conformal anomaly and could be larger than expected. The electrical conductivity gives a prediction for the zero-energy photon spectrum. The thermal ρ behaves consistently with recent data on dileptons, whereas the σ shows signals of chiral restoration compatible with threshold enhancement effects. Pion number chemical potentials are introduced also diagramamtically, taking into account pion interactions in a realistic way and it produces interesting physical effects such as Bose-Einstein condensation or modifications in the freeze-out conditions.

D. Cabrera, A. Dobado, A. Gómez, F. LLanes-Estrada, J.R. Peláez, D. Fernández-Fraile, J. Ruiz de Elvira, R. Torres Andrés, J.M. Torres-Rincon.