Search results for "Relativitat"
showing 10 items of 20 documents
Spritz: General relativistic magnetohydrodynamics with neutrinos
2020
We here present a new version of the publicly available general relativistic magnetohydrodynamic (GRMHD) code $\texttt{Spritz}$, which now includes an approximate neutrino leakage scheme able to handle neutrino cooling and heating. The leakage scheme is based on the publicly available $\texttt{ZelmaniLeak}$ code, with a few modifications in order to properly work with $\texttt{Spritz}$. We discuss the involved equations, physical assumptions, and implemented numerical methods, along with a large battery of general relativistic tests performed with and without magnetic fields. Our tests demonstrate the correct implementation of the neutrino leakage scheme, paving the way for further improvem…
Solutions of the Einstein field equations for a bounded and finite discontinuous source, and its generalization: Metric matching conditions and jumpi…
2019
We consider the metrics of the General Relativity, whose energy-momentum tensor has a bounded support where it is continuous except for a finite step across the corresponding boundary surface. As a consequence, the first derivative of the metric across this boundary could perhaps present a finite step too. However, we can assume that the metric is ${\cal C}^1$ class everywhere. In such a case, although the partial second derivatives of the metric exhibit finite (no Dirac $\delta$ functions) discontinuities, the Dirac $\delta$ functions will still appear in the conservation equation of the energy-momentum tensor. As a consequence, strictly speaking, the corresponding metric solutions of the …
Una propuesta sobre enseñanza de la relatividad en el bachillerato como motivación para el aprendizaje de la física
2007
Relativity is a very important part of modern physics. In this paper we analyze the teaching and learning of the theory of relativity in secondary education and we show some reasoned arguments against traditional methods to teach it. Finally, a didactic proposal for the teaching of relativity is presented; it comes as a conclusion that it is possible a suitable teaching of the principles of relative which should bring into the students a change in attitude, concepts and methodology.
Comprensión de la teoría especial de la relatividad y diseño de una visita guiada a un museo de ciencia
2007
SUMMARY The problem which we are tackling in this work emerges from three different concerns: the importance of `learning science `informally¿ as part of the school curriculum, the need for scientific literacy and the importance of the social implications of contemporary science. An exhibition was used in the Kutxaespacio Science Museum in San Sebastian on the centenary of the Spatial Theory of Relativity to design a visit for first year Engineering students and assess the learning which is achieved. The first part of the work presents the design which was produced to build bridges between formal teaching and the exhibition visit. The second part analyses the potential of the exhibition and…
Algunos problemas en la enseñanza de la relatividad
2021
Resumen. La relatividad es una parte importante de la física moderna. En este artículo se analiza su enseñanza-aprendizaje en la enseñanza secundaria y se muestran sus principales dificultades. El artículo argumenta razonadamente contra prácticas tradicionales en la enseñanza de la relatividad y finalmente apunta una nueva aproximación a su enseñanza. Palabras clave. Enseñanza-aprendizaje, relatividad, didáctica de la física. Summary. Relativity is a very important part of modern physics. In this paper we analyze the teaching and learning of the theory of relativity at secondary school level and we show the pupils¿ main difficulties. This article presents some reasoned arguments against tra…
Precision measurement of D meson mass differences
2013
Using three- and four-body decays of D mesons produced in semileptonic b-hadron decays, precision measurements of D meson mass differences are made together with a measurement of the D-0 mass. The measurements are based on a dataset corresponding to an integrated luminosity of 1.0 fb(-1) collected in pp collisions at 7 TeV. Using the decay D-0 -> K+K-K-pi(+), the D-0 mass is measured to be M(D-0) = 1864.75 +/- 0.15 (stat) +/- 0.11 (syst) MeV/c(2). The mass differences M(D+) - M(D-0) = 4.76 +/- 0.12 (stat) +/- 0.07 (syst) MeV/c(2), M(D-s(+)) - M(D+) = 98.68 +/- 0.03 (stat) +/- 0.04 (syst) MeV/c(2) are measured using the D-0 -> K+K-pi(+)pi(-) and D-(s)(+) -> K+K-pi(+) modes.
Implicaciones de la evolución histórica de algunos conceptos en la enseñanza de la Relatividad
2006
La relatividad es una parte importante de la fisica moderna. En este articulo se analiza el debate en torno a la utilizacion de la historia de la ciencia para orientar la didactica de la relatividad en la ensenanza secundaria. Se repasa la evolucion historica de algunos conceptos clave de la relatividad especial y se muestra su implicacion en la ensenanza-aprendizaje.Palabras clave: ensenanza-aprendizaje; relatividad; historia de la ciencia.Implications of the historical evolution of some concepts in the teaching of relativityThe relativity is an important part the modern physics. In this article we analyze the discussion around the use of the history of science to guide the didactics of th…
Search for neutral Higgs bosons decaying into four taus at LEP2
2010
A search for the production and non-standard decay of a Higgs boson, h, into four taus through intermediate pseudoscalars, a, is conducted on 683 pb-1 of data collected by the ALEPH experiment at centre-of-mass energies from 183 to 209 GeV. No excess of events above background is observed, and exclusion limits are placed on the combined production cross section times branching ratio, β2 = σ(e+e -→Zh)/σSM(e+e-→Zh) ×B(h→aa)×B(a→τ+τ-) 2. For mh 1 is excluded at the 95% confidence level.
Potential perturbation to Friedmann universes
1994
The energy-momentum tensor of perturbed Friedmann universes in the longitudinal gauge (depending on only one gravitational potential) is obtained in order to clarify the physical meaning of two important cases: (1) conformally static perturbations (when the potential is independent of time), and (2) nonstatic perturbations in the case where the potential allows a particular separation of time and space coordinates. The statement according to which the longitudinal gauge allows a description of high-density-contrast regions is analyzed. In the conformally static case we suggest interpreting the energy-momentum tensor as representing a set of particles in gravitational interaction, suitable f…
Cosmic censorship conjecture in some matching spherical collapsing metrics
2017
A physically plausible Lema{\^{\i}}tre-Tolman-Bondi collapse in the marginally bound case is considered. By "physically plausible" we mean that the corresponding metric is ${\cal C}^1$ matched at the collapsing star surface and further that its {\em intrinsic} energy is, as due, stationary and finite. It is proved for this Lema{\^{\i}}tre-Tolman-Bondi collapse, for some parameter values, that its intrinsic central singularity is globally naked, thus violating the cosmic censorship conjecture with, for each direction, one photon, or perhaps a pencil of photons, leaving the singularity and reaching the null infinity. Our result is discussed in relation to some other cases in the current liter…