Gómez Nicola, Ángel2023-06-172023-06-172021-05-281951-635510.1140/epjs/s11734-021-00147-4https://hdl.handle.net/20.500.14352/8269© 2021 Springer Heidelberg. Work partially supported by research contracts FPA2016-75654-C2-2-P (spanish "Ministerio de Economia y Competitividad") and PID2019-106080GB-C21 (spanish "Ministerio de Ciencia e Innovaci ' on"). This work has also received funding from the European Union Horizon 2020 research and innovation programme under grant agreement No 824093. Useful discussion and comments from J.Ruiz de Elvira, A.Vioque, F.Karsch, A.Lahiri, M.P.Lombardo and J.A.Oller are acknowledged.We review recent results on the role of light quark states within the QCD phase diagram. In particular, we will discuss how the combined use of theoretical techniques such as Effective Theories, Unitarization and Ward Identities helps to shed light on several important issues regarding chiral symmetry restoration, building bridges with recent lattice analyses. Special attention will be paid to the role of chiral and U(1)(A) partners in the interplay between those symmetries, which is crucial to properly understand the transition pattern. Light scalar mesons at finite temperature will be shown to be responsible for the description of susceptibilities encoding chiral and U(1)(A) restoration properties.engjournal articlehttp://dx.doi.org/10.1140/epjs/s11734-021-00147-4https://link.springer.com/open access51-73Large-NcPerturbation-theoryLattice GCDMeson massPhasePionTransitionPropagationDileptonsDynamics.Física-Modelos matemáticosFísica matemática