Meson and diquark correlations in a chiral model for normal and color superconducting quark matter
March 13, 2015, at 11:15, room 422
- prof. dr hab. David Blaschke UWr IFT.
- prof. dr Dietmar Ebert – Humboldt University, Berlin,
- prof. dr hab. Wojciech Broniowski – Instytut Fizyki Jądrowej w Krakowie.
The theme of this work is the elaboration of a consistent formalism for the treatment of two-particle correlations in hot and dense quark matter within an effective model of QCD. We study the properties of this Fermi system in the framework of the path integral approach to quantum field theory at finite temperature and density. After a brief discussion of the model in mean field approximation, we perform a systematic expansion beyond the mean field up to second order in the fluctuating fields. Compact expressions for the two-particle polarization functions are derived and analyzed on the basis of their analytical properties in the complex energy plane. The particular choice of the interaction channels allows us to investigate the spontaneously breaking of chiral symmetry (and its restoration), and the formation of a color superconductor due to the Cooper instability at high densities on; two important phenomena characterizing the low temperature region of the QCD phase diagram. A BEC-BCS crossover transition can be triggered, when increasing the diquark coupling strength. It is characterized by the coexistence of q ̄q and qq pairing gaps and coincides with the Mott transition for mesonic and diquark bound states. It is shown, how correlations can be incorporated into the thermodynamic potential of the system, whereby not only bound states but also scattering states of the continuum are included on the same basis. We conclude with a delineation of possible extensions and a critical discussion of limitations inherent to the approach presented.