Modelos quirales para las interacciones fuertes: fenomenología de mesones y transiciones de fase en presencia de campos magnéticos externos

La dinámica de quarks se encuentra descrita en el marco del Modelo Estándar por la Cromodinámica Cuántica (QCD), que formalmente es una teoría de campos de gauge no abeliana. En procesos de altas energías la propiedad de libertad asintótica presente en QCD permite obtener predicciones a partir del lagrangiano fundamental de la teoría. Sin embargo, a bajas energías (≤1 GeV) la constante de acoplamiento fuerte aumenta su valor de modo tal que las técnicas perturbativas ya no son aplicables. En este régimen los quarks se encuentran confinados en hadrones, y la simetría quiral se encuentra espontáneamente rota. El empleo de teorías efectivas permite estudiar la fenomenología de las partículas hadrónicas y analizar el comportamiento de la materia fuertemente interactuante en sistemas con temperatura y densidad finitas. En esta Tesis se estudiaron modelos efectivos para la descripción de la interacción fuerte a bajas energías. En particular, se consideraron modelos de quarks relativistas del tipo Nambu-Jona-Lasinio con interacciones no locales para dos sabores de quarks de modo de estudiar la fenomenología de los mesones livianos. Se estudió también el acoplamiento con campos magnéticos externos uniformes, y el efecto de éstos sobre las propiedades de los mesones y las transiciones de fase que sufre la materia hadrónica a temperatura finita.Facultad de Ciencias Exacta

Vector mesons within nonlocal chiral quark models for strong interactions

We analyze meson properties within an SU(2) chiral quark model that includes nonlocal four fermion couplings with wave function renormalization. Model parameters are determined from meson phenomenology, considering different nonlocal form factor shapes. We concentrate in the description of basic features of nonstrange vector and axial vector mesons, considering nonlocal form factors that are based in lattice QCD results for effective quark propagators.Instituto de Física La Plat

Properties of vector and axial-vector mesons in a nonlocal SU(2) PNJL model

We study the features of a SU(2) Polyakov-Nambu-Jona-Lasinio model that includes wave function renormalization and nonlocal vector interactions. Within this framework we analyze, among other properties, the masses, width, and decay constants of light vector and axial-vector mesons at finite temperature. Then we obtain the corresponding phase diagram in a finite density scenario, after characterizing the deconfinement and chiral restoration transitions.Fil: Carlomagno, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Física; ArgentinaFil: Izzo Villafañe, María Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; Argentin

Vector mesons within nonlocal chiral quark models for strong interactions

We analyze meson properties within an SU(2) chiral quark model that includes nonlocal four fermion couplings with wave function renormalization. Model parameters are determined from meson phenomenology, considering different nonlocal form factor shapes. We concentrate in the description of basic features of nonstrange vector and axial vector mesons, considering nonlocal form factors that are based in lattice QCD results for effective quark propagators.Instituto de Física La Plat

Properties of vector and axial-vector mesons in a nonlocal SU(2) PNJL model

We study the features of a SU(2) Polyakov-Nambu-Jona-Lasinio model that includes wave function renormalization and nonlocal vector interactions. Within this framework we analyze, among other properties, the masses, width, and decay constants of light vector and axial-vector mesons at finite temperature. Then we obtain the corresponding phase diagram in a finite density scenario, after characterizing the deconfinement and chiral restoration transitions.Instituto de Física La Plat

Properties of magnetized neutral pions at zero and finite temperature in nonlocal chiral quark models

The behavior of π0 meson properties in the presence of a uniform external magnetic field is studied in the context of a nonlocal extension of the Polyakov-Nambu-Jona-Lasinio model. The analysis includes the π0 mass, the effective π0-quark coupling and the pion-to-vacuum hadronic form factors, both at zero and finite temperature. Numerical results are compared with previous calculations carried out within the local NJL model, when available. The validity of chiral relations and the features of deconfinement and chiral symmetry restoration transitions are discussed.Fil: Gomez Dumm, Daniel Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Izzo Villafañe, María Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Scoccola, Norberto Nerio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; Argentin

Strong magnetic fields in nonlocal chiral quark models

We study the behavior of strongly interacting matter under a uniform intense external magnetic field in the context of nonlocal extensions of the Polyakov-Nambu-Jona-Lasinio model. A detailed description of the formalism is presented, considering the cases of zero and finite temperature. In particular, we analyze the effect of the magnetic field on the chiral restoration and deconfinement transitions, which are found to occur at approximately the same critical temperatures. Our results show that these models offer a natural framework to account for the phenomenon of inverse magnetic catalysis found in lattice QCD calculations.Fil: Gomez Dumm, Daniel Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Izzo Villafañe, María Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Noguera, S.. Universidad de Valencia; EspañaFil: Pagura, Valeria Paula. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Valencia; EspañaFil: Scoccola, Norberto Nerio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; Argentina. Universidad Favaloro; Argentin

Neutral meson properties under an external magnetic field in nonlocal chiral quark models

We study the behavior of neutral meson properties in the presence of a static uniform external magnetic field in the context of nonlocal chiral quark models. The formalism is worked out introducing Ritus transforms of Dirac fields, which allow to obtain closed analytical expressions for π⁰ and σ meson masses and for the π⁰ decay constant. Numerical results for these observables are quoted for various parametrizations. In particular, the behavior of the π⁰ meson mass with the magnetic field is found to be in good agreement with lattice QCD results. It is also seen that the Goldberger-Treiman and Gell-Mann-Oakes-Renner chiral relations remain valid within these models in the presence of the external magnetic field.Facultad de Ciencias ExactasInstituto de Física La Plat

Vector and axial vector mesons in a nonlocal chiral quark model

Basic features of nonstrange vector and axial vector mesons are analyzed in the framework of a chiral quark model that includes nonlocal four-fermion couplings. Unknown model parameters are determined from some input values of masses and decay constants, while nonlocal form factors are taken from a fit to lattice QCD results for effective quark propagators. Numerical results show a good agreement with the observed meson phenomenology.Instituto de Física La Plat

Strong magnetic fields in nonlocal chiral quark models

We study the behavior of strongly interacting matter under a uniform intense external magnetic field in the context of nonlocal extensions of the Polyakov-Nambu-Jona-Lasinio model. A detailed description of the formalism is presented, considering the cases of zero and finite temperature. In particular, we analyze the effect of the magnetic field on the chiral restoration and deconfinement transitions, which are found to occur at approximately the same critical temperatures. Our results show that these models offer a natural framework to account for the phenomenon of inverse magnetic catalysis found in lattice QCD calculations.Instituto de Física La PlataConsejo Nacional de Investigaciones Científicas y Técnica