“KMI Visitor Seminar” 26th July (Fri)  15：00 –

• Date: July 26th (Fri) 15:00 – 16:00
• Place: ES635
• Speaker: Gergely Fejos (Eotvos Lorand University)
• Title: Order of the chiral phase transition for N_f flavors in the chiral limit

Abstract

Based on the epsilon expansion of the renormalization group flows of the Ginzburg-Landau potential for the chiral phase transition of QCD, it has been widely accepted that it is of first order in the chiral limit for N_f > 2, with the possibility of a second order transition for N_f = 2, given the axial anomaly remains strong enough at the critical point. Recently, several lattice QCD studies hint that the transition can be of second order in the whole range of flavor numbers, after all. In this talk, I reanalyze the renormalization group flows of the Ginzburg-Landau potential using the functional renormalization group technique. Instead of employing the epsilon expansion around d = 4, with the inclusion of all (perturbatively) relevant and marginal interactions directly in d = 3, the method predicts that there exist new fixed points in the whole flavor number range, potentially belonging to conformal systems going through a finite-temperature chiral transition. The results indicate that the chiral transition can be of second order for N_f >= 5, while its nature depends on the strength of the U_A(1) anomaly for N_f = 2,3,4.