The usual theoretical treatments of the near-threshold pp→pp 0 reaction are based on various phenomenological Lagrangians. In this work we examine the relationship between these approaches and a systematic chiral perturbation method. Our chiral perturbation calculation indicates that the pion rescattering term should be significantly enhanced as compared with the traditional phenomenological treatment, and that this term should have substantial energy and momentum dependence. An important consequence of this energymomentum dependence is that, for a representative threshold kinematics and within the framework of our semiquantitative calculation, the rescattering term interferes destructively with the Born term in sharp contrast to the constructive interference obtained in the conventional treatment. This destructive interference makes theoretical cross sections for pp→pp 0 much smaller than the experimental values, a feature that suggests the importance of the heavy-meson exchange contributions to explain the experimental data.

We calculate the physical mass and the width of the sigma meson by considering that it couples in vacuum to two virtual pions. The mass is calculated by using the spectral function, and we find that it is about 600MeV. In addition, we obtained the value of 250MeV for the width of its spectral function. The value obtained for the mass, is in an excellent agreement with that reported in the Particle data Book for the σ -meson, which is also named ). This result also shows that the sigma meson can be considered as a two pion resonance.

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In sustainable education, it is important to analyze student diversity in order to create strategies that allow for the implementation of inclusive education based on the differences observed among students. To achieve this, a sample of 321 first-year engineering students (107 females and 214 males) at a private university in northeast Mexico was analyzed during the 2020 academic year. Students were classified according to their gender, engineering program, and the development of their multiple intelligences according to Howard Gardner theory of multiple intelligences. To verify the effect of gender and program factors on the development of multiple intelligences, Kruskal–Wallis tests were performed with α = 0.05. The analysis of the effects of gender identified significant differences in four intelligences: linguistic and interpersonal (for which the female students obtained higher mean scores) and mathematical and visual (for which the male students obtained higher mean scores). The analysis of the effects of the engineering program identified significant differences in five intelligences: mathematical, visual, and musical (for which civil engineering students obtained a higher mean score than the students in the other programs); kinesthetic (for which computer science students obtained a lower mean score than students in the other programs); and naturalistic (for which sustainability engineering students obtained a higher mean score than students in the other programs). These differences allowed us to observe the characteristics of the students and to develop more inclusive courses in order to make the teaching and learning process more optimal and sustainable.

In this article, the long-distance correction to the total decay width of the AE ! K 0 AE decay is calculated in a model-independent approach, in which a discrimination of photons in the bremmstrahlung process is assumed. This correction is completely free of ultraviolet and infrared singularities, and, moreover, it satisfies electromagnetic gauge invariance. The result of this work can be applied on the tau decays: AE ! AE 0 , K AE 0 .

Abstract:In a system of quark matter we study the chiral phase transition, the behavior of the chiral and quark number susceptibility and the CEP at nite temperature and chemical potential. This is done within the framework of two-avor Nambu and Jona-Lasinio model. We have calculated the chiral quark condensate and the quark number density and, with this, we have found the phase transition type. With these quantities we have determined the phase diagram for QCD and the CEP.

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Working in the SU(2) flavor version of the NJL model, we study the effect of taking a finite system volume on a strongly interacting system of quarks, and, in particular, the location of the chiral phase transition and the CEP. We consider two shapes for the volume, spherical and cubic regions with different sizes and different boundary conditions. To analyze the QCD phase diagram, we use a novel criterion to study the crossover zone. A comparison between the results obtained from the two different shapes and several boundary conditions is carried out. We use the method of Multiple Reflection Expansion to determine the density of states and three kinds of boundary conditions over the cubic shape. These boundary conditions are: periodic, anti-periodic and stationary boundary conditions on the quark fields.