Cortés, SantiagoGómez Nicola, ÁngelMorales, John2023-06-172023-06-172016-12-212470-001010.1103/PhysRevD.94.116008https://hdl.handle.net/20.500.14352/18274© 2016 Amer Physical Soc. Work partially supported by Contracts No. FPA2014- 53375-C2-2-P and No. FIS2014-57026-REDT (Spanish Hadron Excelence Network) from the Spanish “Ministerío de Economia y Competitividad.” We also acknowledge the support of the HadronPhysics3 project from the European Union Seventh Framework Programme (EU-FP7). S. Cortés thanks Professor José Rolando Roldán and the High Energy Physics group of Universidad de los Andes and Colombian “Departamento Administrativo de Ciencia, Tecnologia e Innovacion” (COLCIENCIAS) for financial support.We analyze chiral restoration within the O(N + 1)/ O(N) nonlinear sigma model for large N as an effective theory for low-energy QCD at finite temperature T. The free energy is constructed diagrammatically to O(TM^3) in the pion mass expansion, which allows us to derive the quark condensate and the scalar susceptibility in the chiral limit. At this order, we do not have to deal with renormalization, either from divergences from mass tadpoles or from those of higher order loop contributions. Our results for the critical behavior are consistent with expectations from lattice analysis and with previous works where the susceptibility is saturated by the thermal f₀(500) pole.engjournal articlehttp://dx.doi.org/10.1103/PhysRevD.94.116008https://journals.aps.orgopen access51-73Nonlinear sigma-modelFinite-temperaturePerturbation-theoryOne-loopPhase-transitionExpansionLimitFísica-Modelos matemáticosFísica matemática