We discuss the role of the U(1) axial symmetry for the scalar and pseudoscalar meson mass spectrum of QCD at finite temperature, above the chiral transition at T_c, using a chiral effective Lagrangian model, which, in addition to the usual chiral condensate, also includes a (possible) genuine U(1)_A-breaking condensate that (possibly) survives across the chiral transition. The motivations for considering this Lagrangian (and a critical comparison with other effective Lagrangian models existing in the literature) are presented. A detailed comparison between the case N_f=3 (or N_f>3) and the (remarkably different) case N_f=2 is performed. The results obtained in the case N_f=2 are also critically compared with the available lattice results.
|Autori:||Meggiolaro, Enrico; Alessandro, Mordà|
|Titolo:||Remarks on the U(1) axial symmetry and the chiral transition in QCD at finite temperature|
|Anno del prodotto:||2013|
|Digital Object Identifier (DOI):||10.1103/PhysRevD.88.096010|
|Appare nelle tipologie:||1.1 Articolo in rivista|