Speaker
Description
We will review recent progress towards the understanding of chiral and $U(1)_A$ symmetry restoration within the QCD phase diagram, arising from our results on effective theories, Ward Identities (WI) and resonances at finite temperature and chemical potentials. Our approach allows to control in a systematic and consistent way the dependence on relevant variables such as quark masses, strangeness or the number of colors.
For isospin channels $I=0,1,1/2$ we provide results for the $f_0(500) (\sigma)$, $K_0^* (700) (\kappa)$, $\rho (770)$ and $K^* (892)$ thermal resonance poles generated respectively from $\pi\pi$ and $\pi K$ scattering at finite temperature in unitarized Chiral Perturbation Theory, and their nature around the transition region. Those resonances provide useful insight for chiral and $U(1)_A$ symmetry restoration consistently with lattice analyses, mainly through scalar susceptibilities obtained within the so called saturation approach.
On the other hand, WI provide results for scalar-pseudoscalar partner degeneration around chiral restoration consistent with lattice and with our effective theory analysis. In turn, based on WI, one can derive scaling laws around $T_c$ in agreement with lattice screening masses.
We will also review novel results for effective theories and thermal resonances including nonzero isospin density or nonzero chiral imbalance.