Vacuum stability with spontaneous violation of lepton number

The vacuum of the Standard Model is known to be unstable for the measured values of the top and Higgs masses. Here we show how vacuum stability can be achieved naturally if lepton number is violated spontaneously at the TeV scale. More precise Higgs measurements in the next LHC run should provide a crucial test of our symmetry breaking scenario. In addition, these schemes typically lead to enhanced rates for processes involving lepton flavour violation .Comment: 9 pages, 4+2 figures; some references added, some textual modifications: 2 figures added, appendices added. Results unchanged. Matches published versio

Flavour-symmetric type-II Dirac neutrino seesaw mechanism

We propose a Standard Model extension with underlying A4 flavour symmetry where small Dirac neutrino masses arise from a Type-II seesaw mechanism. The model predicts the "golden" flavour-dependent bottom-tau mass relation, requires an inverted neutrino mass ordering and non-maximal atmospheric mixing angle. Using the latest neutrino oscillation global fit we derive restrictions on the oscillation parameters, such as a correlation between Dirac CP phase and the lightest neutrino mass.Comment: 10 pages, 4 figure

Higgs decay into two photons from a 3HDM with flavor symmetry

In this short letter we show that the excess of events in the decay of Higgs to two photons reported by ATLAS and CMS can be easily accommodated in a flavor renormalizable three Higgs doublet model (3HDM). The model is consistent with all fermion masses, mixing angles, and flavor changing neutral current constraints.Comment: 4 pages, 3 figures, version to be published in PL

Situación de la tuberculosis en el Perú

Cada año se registran 220 000 nuevos casos de tuberculosis en la Región de las Américas y mueren mas de 50 000 personas a consecuencia de esta enfermedad.Uno de los aspectos más importantes y fascinantes en relación a la tuberculosis, es que es una enfermedad 100% curable y prevenible, sin embargo se ha convertido en la infección trasmisible más importante en los seres humanos. En el Perú una comprensión cabal de la situación de la epidemia de la tuberculosis en el país, permite aplicar eficazmente las herramientas disponibles para su control, incrementando la eficiencia de las intervenciones habiendosé logrado considerables progresos en prevención y control de la tuberculosis, asi en el año 1992 se notificaron en total mas de 55 mil casos, mientras que el 2007, se ha logrado reducir esta cifra en 32,7 %, la meta al 2011 es disminuir el número de casos en 50%. Tambien se ha mejorado e incrementado la la capacidad diagnostica de TB MDR Y TB XDR. No obstante, tanto la TB MDR, TB XDR, la comorbilidad TB/VIH-SIDA, el estigma, la discriminación y lo complicado de las intervenciones técnicas, socioeconómicas y culturales, significan un reto para el mejoramiento. El 58 % de casos de TB, 82 % de casos de TB MDR y 93 % de casos de TB XDR son notificados por Lima y Callao. El primer caso de TB XDR1,2 , fue notificado el año de 1999 y hasta agosto del 2008 se han notificado 186 casos acumulados, de los cuales el 85 % se concentran en los distritos de La Victoria, Lima Cercado, San Martin de Porres, San Juan de Lurigancho, Ate, Santa Anita y El Agustino

Implications of helminth immunomodulation on COVID-19 co-infections

Coronavirus disease 2019 (COVID-19) and helminths infections can be in a synergistic epidemic in developing and suburban areas of industrialized countries. The coinfected hosts will derive a parasite-specific Th2 innate and adaptive immune response with CD4+ T cells, eosinophils, interleukin-4, interleukin-5, and interleukin-10. In the early stages of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) infection, virus-specific Th1 cytotoxic CD8+ T cell, interleukin-6, interferon-γ, and interleukin-27 by lung are keys in controlling viral replication in the lung epithelial cells and limiting the pathology to other organs, like the intestine. CD4+ and CD8+ T cells are associated with protective immunity against and during COVID-19. However, viral evasion mechanisms occur. Interference of the interferon-γ secretion, like in helminths immunomodulation, can contribute to COVID-19 severity. Immunomodulation can result in mild, moderate, or severe COVID-19 depending on which helminth is coinfecting by regulating or avoiding host cytokine and pro-inflammatory response, decreasing viral load, and affecting vaccine-induced antibody response. We discuss the implications of immunomodulation on COVID-19 caused by helminth co-infection and for public health in the context of COVID-19 vaccine use in helminth endemic zones