Supporting the search for the CEP location with nonlocal PNJL models constrained by Lattice QCD

We investigate the possible location of the critical endpoint in the QCD phase diagram based on nonlocal covariant PNJL models including a vector interaction channel. The form factors of the covariant interaction are constrained by lattice QCD data for the quark propagator. The comparison of our results for the pressure including the pion contribution and the scaled pressure shift $\Delta P / T^4$ vs $T/T_c$ with lattice QCD results shows a better agreement when Lorentzian formfactors for the nonlocal interactions and the wave function renormalization are considered. The strength of the vector coupling is used as a free parameter which influences results at finite baryochemical potential. It is used to adjust the slope of the pseudocritical temperature of the chiral phase transition at low baryochemical potential and the scaled pressure shift accessible in lattice QCD simulations. Our study, albeit presently performed at the meanfield level, supports the very existence of a critical point and favors its location within a region that is accessible in experiments at the NICA accelerator complex.Comment: 7 pages, 7 Figures. Version accepted by Eur. Phys. J. A as part of the topical collection: Exploring strongly interacting matter at high densities - NICA White Pape

Neutrino emissivity in the quark-hadron mixed phase of neutron stars

Numerous theoretical studies using various equation of state models have shown that quark matter may exist at the extreme densities in the cores of high-mass neutron stars. It has also been shown that a phase transition from hadronic matter to quark matter would result in an extended mixed phase region that would segregate phases by net charge to minimize the total energy of the phase, leading to the formation of a crystalline lattice. The existence of quark matter in the core of a neutron star may have significant consequences for its thermal evolution, which for thousands of years is facilitated primarily by neutrino emission. In this work we investigate the effect a crystalline quark-hadron mixed phase can have on the neutrino emissivity from the core. To this end we calculate the equation of state using the relativistic mean-field approximation to model hadronic matter and a nonlocal extension of the three-flavor Nambu-Jona-Lasinio model for quark matter. Next we determine the extent of the quark-hadron mixed phase and its crystalline structure using the Glendenning construction, allowing for the formation of spherical blob, rod, and slab rare phase geometries. Finally we calculate the neutrino emissivity due to electron-lattice interactions utilizing the formalism developed for the analogous process in neutron star crusts. We find that the contribution to the neutrino emissivity due to the presence of a crystalline quark-hadron mixed phase is substantial compared to other mechanisms at fairly low temperatures ($\lesssim 10^9$ K) and quark fractions ($\lesssim 30\%$), and that contributions due to lattice vibrations are insignificant compared to static-lattice contributions.Comment: 12 pages, 10 figures; accepted for publication in the European Physical Journal A - "Hadrons and Nuclei.

Nonlocal SU(3) chiral quark models at finite temperature: the role of the Polyakov loop

We analyze the role played by the Polyakov loop in the description of the chiral phase transition within the framework of nonlocal SU(3) chiral models with flavor mixing. We show that its presence provides a substantial enhancement of the predicted critical temperature, bringing it to a better agreement with the most recent results of lattice calculations.Comment: 9 pages, 1 figur

Implementación de los entornos virtuales de aprendizaje en cursos de capacitación docente

El uso de entornos virtuales de aprendizaje (eva), adoptado por instituciones educativas de distintos niveles, diversos ámbitos de formación y empresas, ha crecido notablemente en los últimos años. En este trabajo presentamos como caso la implementación de cursos de formación docente a distancia dentro del ámbito de la Escuela de Capacitación Docente del Centro de Pedagogías de Anticipación (cepa) del Ministerio de Educación del Gobierno la Ciudad de Autónoma de Buenos Aires, donde la demanda de este tipo de entornos, tanto para la oferta de cursos a distancia como para el apoyo a capacitaciones presenciales y semipresenciales, dio lugar a la implementación de tres nuevas plataformas educativas dedicadas a cubrir cada una de estas necesidades específicas. El artículo se estructura en tres partes. La primera presenta el escenario de implementación donde se describe el contexto particular de una capacitación docente llevada a cabo en un eva; la segunda parte aborda un análisis de la propuesta realizado en torno a tres ejes sobre la base de las categorías conceptuales y dimensiones analíticas utilizadas por Bordignon y otros (2001): las mediaciones didáctico-tecnológicas en los procesos de enseñanza y de aprendizaje operados; los procesos y estrategias que suponen la reconfiguración de los perfiles y roles de estudiantes y docentes, y, por último, los procesos de cambio a nivel de la institución. Finalmente, en la tercera parte, se manifiesta que se ha abordado la compleja instancia educativa desde respuestas elaboradas para cada objetivo en particular con actividades y recursos tic que hacen posible su concreción desde una perspectiva centrada en el alumno y no en las tecnologías, así como las cuestiones de la reconfiguración de roles, la incorporación de la experiencia al quehacer en el aula, y también el compartirla a nivel institucional y para implementar mejoras en algunas áreas de gestión administrativa

Neutrino Emissivity in the Quark-Hadron Mixed Phase

In this work we investigate the effect a crystalline quark–hadron mixed phase can have on the neutrino emissivity from the cores of neutron stars. To this end we use relativistic mean-field equations of state to model hadronic matter and a nonlocal extension of the three-flavor Nambu–Jona–Lasinio model for quark matter. Next we determine the extent of the quark–hadron mixed phase and its crystalline structure using the Glendenning construction, allowing for the formation of spherical blob, rod, and slab rare phase geometries. Finally, we calculate the neutrino emissivity due to electron–lattice interactions utilizing the formalism developed for the analogous process in neutron star crusts. We find that the contribution to the neutrino emissivity due to the presence of a crystalline quark–hadron mixed phase is substantial compared to other mechanisms at fairly low temperatures (≲10 9 K) and quark fractions (≲30%), and that contributions due to lattice vibrations are insignificant compared to static-lattice contributions. There are a number of open issues that need to be addressed in a future study on the neutrino emission rates caused by electron–quark blob bremsstrahlung. Chiefly among them are the role of collective oscillations of matter, electron band structures, and of gaps at the boundaries of the Brillouin zones on bremsstrahlung, as discussed in the summary section of this paper. We hope this paper will stimulate studies addressing these issues

Quark Deconfinement in Rotating Neutron Stars

In this paper, we use a three flavor non-local Nambu–Jona-Lasinio (NJL) model, an improved effective model of Quantum Chromodynamics (QCD) at low energies, to investigate the existence of deconfined quarks in the cores of neutron stars. Particular emphasis is put on the possible existence of quark matter in the cores of rotating neutron stars (pulsars). In contrast to non-rotating neutron stars, whose particle compositions do not change with time (are frozen in), the type and structure of the matter in the cores of rotating neutron stars depends on the spin frequencies of these stars, which opens up a possible new window on the nature of matter deep in the cores of neutron stars. Our study shows that, depending on mass and rotational frequency, up to around 8% of the mass of a massive neutron star may be in the mixed quark-hadron phase, if the phase transition is treated as a Gibbs transition. We also find that the gravitational mass at which quark deconfinement occurs in rotating neutron stars varies quadratically with spin frequency, which can be fitted by a simple formula

Revista iberoamericana de educación

Resumen basado en el de la publicaciónTítulo, resumen y palabras clave en español, portugués e inglésMonográfico con el título: "Entornos Virtuales de Aprendizaje en Iberoamérica"El uso de entornos virtuales de aprendizaje (EVA), adoptado por instituciones educativas de distintos niveles, diversos ámbitos de formación y empresas, ha crecido notablemente en los últimos años. Se presenta como caso la implementación de cursos de formación docente a distancia dentro del ámbito de la Escuela de Capacitación Docente del Centro de Pedagogías de Anticipación del Ministerio de Educación del Gobierno la Ciudad de Autónoma de Buenos Aires. Primero se presenta el escenario de implementación donde se describe el contexto particular de una capacitación docente llevada a cabo en un EVA; luego se realiza un análisis de la propuesta en torno a tres ejes sobre la base de las categorías conceptuales y dimensiones analíticas utilizadas por Bordignon y otros (2001): las mediaciones didáctico-tecnológicas en los procesos de enseñanza y de aprendizaje operados; los procesos y estrategias que suponen la reconfiguración de los perfiles y roles de estudiantes y docentes, y, por último, los procesos de cambio a nivel de la institución. Finalmente, se manifiesta que se ha abordado la compleja instancia educativa desde respuestas elaboradas para cada objetivo en particular con actividades y recursos tic que hacen posible su concreción desde una perspectiva centrada en el alumno y no en las tecnologías, así como las cuestiones de la reconfiguración de roles, la incorporación de la experiencia al quehacer en el aula, y también el compartirla a nivel institucional y para implementar mejoras en algunas áreas de gestión administrativa.ES

Phase transitions in neutron stars and their links to gravitational waves

International audienceThe recent direct observation of gravitational wave event GW170817 and its signal has opened up a new window to studying neutron stars and heralds a new era of astronomy referred to as the multimessenger astronomy. Both gravitational and electromagnetic waves from a single astrophysical source have been detected for the first time. This combined detection offers an unprecedented opportunity to place constraints on the neutron star matter equation of state (EoS). The existence of a possible hadron–quark phase transition in the central regions of neutron stars is associated with the appearance of g modes, which are extremely important as they could signal the presence of a pure quark matter core in the centers of neutron stars. Observations of g modes with frequencies between 1 and 1.5 kHz could be interpreted as evidence of a sharp hadron–quark phase transition in the cores of neutron stars. In this article, we shall review the description of the dense matter composing neutron stars, the determination of the EoS of such matter, and the constraints imposed by astrophysical observations of these fascinating compact objects