Weak Mixing Angle in the Thomson Limit

We present a calculation of the weak mixing angle in the $\overline{\rm\small MS}$ renormalization scheme which is relevant for experiments performed at very low energies or momentum transfers. We include higher orders in the perturbative QCD expansion, as well as updated phenomenological and theoretical input, and obtain the result $\sin^{2}{\theta}_W(0) = 0.23868(5)(2)$ for the reference values $\alpha_s(M_Z) = 0.1182$ and $m_c(m_c) = 1.272$ GeV. The first quoted error is from the current Standard Model evaluation of the mixing angle at the $Z$ boson mass scale. The second error represents the theoretical and parametric uncertainties induced by the evolution to the Thomson limit and is discussed in detail.Comment: 22 pages, 3 figures; one formula extended with corresponding very small numerical changes; one table and four references adde

Quantization of Second Order Fermions

The quantization of a massive spin $1/2$ field that satisfies the Klein-Gordon equation is studied. The framework is consistent, provided it is formulated as a pseudo-hermitian quantum field theory by the redefinition of the field dual and the identification of an operator that modifies the internal product of states in Hilbert space to preserve a real energy spectrum and unitary evolution. Since the fermion field has mass dimension one, the theory admits renormalizable fermion self-interactions.Comment: 4 page

¡Cuidémonos entre todos! : Parte II

Es de vital importancia la bioseguridad, ya que se encarga de disminuir el riesgo para la salud y el medio ambiente proveniente de la exposición a agentes biológicos causantes de enfermedades. Nuestras acciones en el marco de la Pandemia Covid-19, fueron orientadas a lograr actitudes y conductas responsables, que disminuyan la posibilidad de adquirir infecciones. El objetivo fue: proporcionar información sobre el manejo preventivo frente a los microorganismos potencialmente patógenos con poder de riesgo de contaminación biológica como lo es el virus Sars-cov2. Las actividades se realizaron mediante la organización de charlas virtuales, producción de videos informativos, armado de power point, preparación de material didáctico, diagramación de folletos, instructivos y elementos de bioseguridad para la higiene de manos.Facultad de Odontologí

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

Perturbative contributions to Δ α 5 M Z 2 Δα(5)(MZ2) \Delta {\alpha}^{(5)}\left({M}_Z^2\right)

Abstract We compute a theoretically driven prediction for the hadronic contribution to the electromagnetic running coupling at the Z scale using lattice QCD and state-of-the-art perturbative QCD. We obtain Δ α 5 M Z 2 = 279.5 ± 0.9 ± 0.59 × 10 − 4 Mainz Collaboration Δ α 5 M Z 2 = 278.42 ± 0.22 ± 0.59 × 10 − 4 BMW Collaboration , $${\displaystyle \begin{array}{cc}\Delta {\alpha}^{(5)}\left({M}_Z^2\right)=\left[279.5\pm 0.9\pm 0.59\right]\times {10}^{-4}& \left(\textrm{Mainz}\ \textrm{Collaboration}\right)\\ {}\Delta {\alpha}^{(5)}\left({M}_Z^2\right)=\left[278.42\pm 0.22\pm 0.59\right]\times {10}^{-4}& \left(\textrm{BMW}\ \textrm{Collaboration}\right),\end{array}}$$ where the first error is the quoted lattice uncertainty. The second is due to perturbative QCD, and is dominated by the parametric uncertainty on α ̂ s $${\hat{\alpha}}_s$$ , which is based on a rather conservative error. Using instead the PDG average, we find a total error on Δ α 5 M Z 2 $$\Delta {\alpha}^{(5)}\left({M}_Z^2\right)$$ of 0.4 × 10 −4. Furthermore, with a particular emphasis on the charm quark contributions, we also update Δ α 5 M Z 2 $$\Delta {\alpha}^{(5)}\left({M}_Z^2\right)$$ when low-energy cross-section data is used as an input, obtaining Δ α 5 M Z 2 $$\Delta {\alpha}^{(5)}\left({M}_Z^2\right)$$ = [276.29 ± 0.38 ± 0.62] × 10 −4. The difference between lattice QCD and cross-section-driven results reflects the known tension between both methods in the computation of the anomalous magnetic moment of the muon. Our results are expressed in a way that will allow straightforward modifications and an easy implementation in electroweak global fits