Contemporary continuum QCD approaches to excited hadrons

Amongst the bound states produced by the strong interaction, radially excited meson and nucleon states offer an important phenomenological window into the long-range behavior of the coupling constant in Quantum Chromodynamics. We here report on some technical details related to the computation of the bound state's eigenvalue spectrum in the framework of Bethe-Salpeter and Faddeev equations.Comment: Proceedings of the 21st International Conference on Few-body Problems in Physics to be published in EPJ Web of Conference

Excited hadrons and the analytical structure of bound-state interaction kernels

We highlight Hermiticity issues in bound-state equations whose kernels are subject to a highly asymmetric mass and momentum distribution and whose eigenvalue spectrum becomes complex for radially excited states. We trace back the presence of imaginary components in the eigenvalues and wave functions to truncation artifacts and suggest how they can be eliminated in the case of charmed mesons. The solutions of the gap equation in the complex plane, which play a crucial role in the analytic structure of the Bethe-Salpeter kernel, are discussed for several interaction models and qualitatively and quantitatively compared to analytic continuations by means of complex-conjugate pole models fitted to real solutions.Comment: Proceeding of the ECT* workshop "Nucleon Resonances From Photoproduction to High Photon Virtualities", talk given by B.E.; 8 pages, 2 figures with 6 graph

Mass spectrum and decay constants of radially excited vector mesons

We calculate the masses and weak decay constants of flavorless ground and radially excited $J^P=1^-$ mesons and the corresponding quantities for the K^*, within a Poincar\'e covariant continuum framework based on the Bethe-Salpeter equation. We use in both, the quark's gap equation and the meson bound-state equation, an infrared massive and finite interaction in the leading symmetry-preserving truncation. While our numerical results are in rather good agreement with experimental values where they are available, no single parametrization of the QCD inspired interaction reproduces simultaneously the ground and excited mass spectrum, which confirms earlier work on pseudoscalar mesons. This feature being a consequence of the lowest truncation, we pin down the range and strength of the interaction in both cases to identify common qualitative features that may help to tune future interaction models beyond the rainbow-ladder approximation

A fluorometric method for the assay of protein kinase activity

Protein kinases constitute one of the largest protein families in nature. Current methods to assay their activity involve the use of radioactive ATP or very expensive reagents. In this work, we developed a highly sensitive, cost-effective and straightforward protocol to measure protein kinase activity using a microplate layout. Released ADP is converted into NAD+, which is quantified by its fluorescent properties after alkaline treatment (linear range 0–10 nmol ADP). To validate our protocol, we characterized a recombinant calcium-dependent protein kinase from potato. Overall, this tool represents a critical step forward in the functional characterization of protein kinases.Fil: Rojas, Bruno Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; ArgentinaFil: Santin, Franco. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Ulloa, Rita Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Iglesias, Alberto Alvaro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; ArgentinaFil: Figueroa, Carlos Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentin

Real-Life Radioactive Men

A common perception in modern society is that exposure to any amount of radiation is a bad thing and should be avoided at all costs. In the fictional superhero genre, exposure to radiation has been used as a vehicle to enable superpowers in what were previously ordinary humans. For instance, Dr Chen Lu, a Nuclear Physicist otherwise known as Radioactive Man, exposed himself to increasing amounts of radiation until he could endure a massive barrage, and in the process turned himself into Radioactive Man. In a similar fashion, Bruce Banner was exposed to a large amount of gamma radiation, giving him the superpowers of the Incredible Hulk. Although there is an element of truth in that the body can withstand low levels of radiation without any observable effects, there are many harmful side effects of being exposed to high levels of radiation. These harmful side effects form the underlying fear of the general publics’ understanding of radiation exposure. This article will explore in detail the reasoning behind the principles of radiation safety, and how different types of damage are caused to the human body when exposed to radiation. Furthermore, we discuss how cellular mutations are caused, as well as the potential of organisms to develop resistance to the harmful effects of radiation and the beneficial uses of radiation in the medical field for diagnosis and cancer treatment

Romper las fronteras. Las luchas de las organizaciones de migrantes y la emergencia de una reivindicación antirracista (1998-2018, Santiago)

Since the mid-nineties, the Latin American and Caribbean migration that has arrived in the country has sought to integrate into social life in our cities. In Santiago, migrant communities had to face a series of social violence and exclusion processes based on a series of racialization and de-citizenization practices, constituting a social heterogeneity of support networks and social organizations. This article affirms the need to question certain analytical frameworks in order to understand the agency of migrants in the face of racialization processes and contribute in this sense by exploring the organizational and demands dynamics of migrant organizations. In this context, this article explores from a sociohistorical perspective a line of development of these organizations that went from being spaces of mutual support for their social insertion led by peruvian political refugees, to the development of social and sectoral organizations, maturing politically and organizationally in articulation processes that have come to have a national scale and links with other social movements. Process in which they have raised a series of claims to end the exclusions and racism faced by their communities, framing their struggles in a discourse on human rights that extends its recognition to all inhabitants regardless of nationality or skin color, having in his agency a democratizing role in Chilean society.Desde mediados de los noventa la migración latinoamericana y caribeña que ha arribado a Chile ha buscado integrarse a la vida social en nuestras ciudades. En Santiago, las comunidades de migrantes tuvieron que hacer frente a una serie de violencias sociales y procesos de exclusión a partir de una serie prácticas de racialización y desciudadanización, constituyendo para insertarse socialmente una heterogeneidad de redes de apoyo y organizaciones sociales. En este artículo se afirma la necesidad de cuestionar ciertos marcos analíticos para comprender la agencia de los migrantes ante los procesos de racialización y contribuye en este sentido explorando las dinámicas organizativas y reivindicativas de las organizaciones de migrantes. En este contexto, este artículo explora desde un enfoque sociohistórico los procesos organizativos, la acción colectiva y los marcos reivindicativos de las organizaciones de migrantes en Santiago desde fines de los noventas hasta el 2018. Seguimos así una línea de desarrollo de estas organizaciones que pasaron de ser espacios de apoyo mutuo para su inserción social conducidas por refugiados políticos peruanos, hasta el desarrollo de organizaciones sociales y sectoriales, madurando política y organizacionalmente en procesos de articulación que han llegado a tener escala nacional y vinculaciones con otros movimientos sociales. Proceso en el cual han levantado una serie de demandas para terminar con las exclusiones, discriminaciones y el racismo que enfrentan sus comunidades, enmarcando sus luchas en un discurso sobre los derechos humanos que extienda su reconocimiento a todos los habitantes sin importar nacionalidad ni color de piel, teniendo en su agencia un rol democratizador en la sociedad chilena.    Desde meados dos anos 90, a migração da América Latina e do Caribe que chegou ao país tentou se integrar à vida social de nossas cidades. Em Santiago, as comunidades que vivenciaram esse processo tiveram que enfrentar uma série de violência social, discriminação institucional, articulada por práticas de racialização, que constituíram uma heterogeneidade de redes de apoio e organizações sociais. Nesse contexto, este artigo explora uma linha de desenvolvimento dessas organizações que passou da construção de organizações de apoio mútuo para sua inserção social, liderada por grupos de refugiados peruanos, ao desenvolvimento de organizações sindicais setoriais que amadurecem em processos de articulação em escala nacional e vínculos com outros movimentos sociais. Nesse sentido, a hipótese que defendo neste artigo afirma que as organizações de migrantes melhoraram seu desenvolvimento a partir da crescente imigração intra-regional que abalou a cidade, bem como das queixas causadas pelos processos de racialização e violência explícita que eles sofreram. comunidades Nesse desenvolvimento, essas organizações tendiam a participar do processo de reativação das mobilizações da sociedade civil e dos movimentos sociais, desempenhando um papel democratizante da sociedade, conseguindo articular suas demandas e projetos sociais particulares.       &nbsp

Completing the picture of the Roper resonance

We employ a continuum approach to the three valence-quark bound-state problem in relativistic quantum field theory to predict a range of properties of the proton's radial excitation and thereby unify them with those of numerous other hadrons. Our analysis indicates that the nucleon's first radial excitation is the Roper resonance. It consists of a core of three dressed-quarks, which expresses its valence-quark content and whose charge radius is 80% larger than the proton analogue. That core is complemented by a meson cloud, which reduces the observed Roper mass by roughly 20%. The meson cloud materially affects long-wavelength characteristics of the Roper electroproduction amplitudes but the quark core is revealed to probes with $Q^2 \gtrsim 3 m_N^2$.Comment: 6 pages, 3 figure