Tau Decay Determination of the Strange Quark Mass

The recent ALEPH measurements of the inclusive Cabibbo--suppressed decay width of the $\tau$ and several moments of its invariant mass distribution are used to determine the value of the strange quark mass. We obtain, in the $\bar{\rm MS}$ scheme, $m_s(M_\tau^2) = (119\pm 24)$ MeV, which corresponds to $m_s(1 {\rm GeV}^2) = (164 \pm 33) {\rm MeV}, m_s(4 {\rm GeV}^2) = (114\pm 23) {\rm MeV}$.Comment: 5pages. Invited talk at QCD'99 (Montpellier, July 1999

Chiral low-energy constants from tau data

We analyze how the recent precise hadronic tau-decay data on the V-A spectral function and general properties of QCD such as analyticity, the operator product expansion and chiral perturbation theory (ChPT), can be used to improve the knowledge of some of the low-energy constants of ChPT. In particular we find the most precise values of L_{9,10} (or equivalently l_{5,6}) at order p^4 and p^6 and the first phenomenological determination of C_87 (c_50).Comment: Proceedings of the 6th International Workshop on Chiral Dynamics (Bern, Switzerland, July 6-10, 2009). 9 pages, 3 figure

Strange Quark Mass from the Invariant Mass Distribution of Cabibbo-Suppressed Tau Decays

Quark mass corrections to the tau hadronic width play a significant role only for the strange quark, hence providing a method for determining its mass. The experimental input is the vector plus axial-vector strange spectral function derived from a complete study of tau decays into strange hadronic final states performed by ALEPH. New results on strange decay modes from other experiments are also incorporated. The present analysis determines the strange quark mass at the Mtau mass scale using moments of the spectral function. Justified theoretical constraints are applied to the nonperturbative components and careful attention is paid to the treatment of the perturbative expansions of the moments which exhibit convergence problems. The result obtained, m_s(Mtau^2) = (120 +- 11_exp +- 8_Vus +- 19_th) MeV = (120^+21_-26) MeV, is stable over the scale from Mtau down to about 1.4 GeV. Evolving this result to customary scales yields m_s(1 GeV^2) = (160^+28_-35) MeV and m_s(4 GeV^2) = (116^+20_-25) MeV.Comment: LaTex, 8 pages, 4 figures (EPS

Determination of |V_us| from hadronic tau decays

The recent update of the strange spectral function and the moments of the invariant mass distribution by the OPAL collaboration from hadronic tau decay data are employed to determine |V_us| as well as m_s. Our result, |V_us|=0.2208\pm0.0034, is competitive to the standard extraction of |V_us| from K_e3 decays and to the new proposals to determine it. Furthermore, the error associated to our determination of |V_us| can be reduced in the future since it is dominated by the experimental uncertainty that will be eventually much improved by the B-factories hadronic tau data. Another improvement that can be performed is the simultaneous fit of both |V_us| and m_s to a set of moments of the hadronic tau decays invariant mass distribution, which will provide even a more accurate determination of both parameters.Comment: 6 pages. Invited talk given by E.G. at the XXXXth Rencontres de Moriond on Electroweak Interactions and Unified Theories, La Thuile, Italy, 5-12 Mar 200

Stop as a next-to-lightest supersymmetric particle in constrained MSSM

So far the squarks have not been detected at the LHC indicating that they are heavier than a few hundred GeVs, if they exist. The lighter stop can be considerably lighter than the other squarks. We study the possibility that a supersymmetric partner of the top quark, stop, is the next-to-lightest supersymmetric particle in the constrained supersymmetric standard model. Various constraints, on top of the mass limits, are taken into an account, and the allowed parameter space for this scenario is determined. Observing stop which is the next-to-lightest supersymmetric particle at the LHC may be difficult.Comment: v2: A few references, a plot indicating used parameters, discussion about the role of parameters in determination of the stop NLSP, CCB minima and a comment about (g-2) added. Typos corrected. Version in PR

Durkheim, the Sacred and Environmental Crisis in the Contemporary Industrial Society

Este artículo presenta una lectura heurística de Las formas elementales de la vida religiosa. Contiene dos partes. La primera trata unos prolegómenos teóricos y metodológicos y la segunda pasa a considerar una aplicación práctica. Los prolegómenos precisan los conceptos de lectura y de lectura heurística, para recordar luego el valor heurístico concreto que damos a una serie de conceptos de base de la obra durkheimiana. La interdependencia y la integración de estos conceptos nos dan una idea concisa del núcleo central del pensamiento de Durkheim en lo que toca a la relación entre lo sagrado y el mundo contemporáneo. La aplicación práctica nos parece más ambiciosa, ya que se refiere directamente al excepcional problema del calentamiento climático y de la degradación constante del medio ambiente que vivimos desde hace unas décadas. Después de indicar en sus grandes líneas las causas societales determinantes de este problema, entramos en la cuestión delicada del remedio que es necesario encontrar para poder sobrevivir, nosotros, nuestros hijos y nuestros nietos. Para entrar de manera concreta en estas causas y remedios, nuestra lectura de FE nos lleva a considerar la importancia suprema del concepto de sagrado que, para expresarlo en términos puramente positivos y naturales, calificamos de valor ético fundamental que orienta el comportamiento de las personas y de los grupos sociales. El artículo termina sometiendo a consideración los elementos de un cambio social alternativo que, siguiendo las posiciones de Durkheim, incluya a la vez, estos valores éticos fundamentales y las condiciones organizativas, económicas y sociales.This paper presents a heuristic reading of The Elementary Forms of the Religious Life. It includes two parts. The first one deals with theoretical and methodological prolegomena and the second, with a practical application. The prolegomena specify previously the notions of reading and of heuristic reading, and later the heuristic value that we attribute to a series of basic durkheimian concepts. The interdependence and integration of these concepts offers a concise idea on the hard core of the sociological theory concerned with sacred and profane throughout The Forms The practical application seems vaster and more ambitious. It refers directly to the exceptional problem of climate change and the constant degradation of natural environment that we are suffering these last decades. After showing broadly the societal determinant causes of climate change, we go into the critical question of the remedies that are necessary to survive, ourselves, our children and our grand children. To study concretely these causes and these remedies, our reading of The Forms leads to consider the major importance of the crucial term of sacred. A term which, in order to employ a positive and neutral vocabulary, will be called as the founding ethical value that guides the behaviour of people and of social groups. This paper ends with an appeal to a kind of social alternative change that, following Durkheim’s insights, includes simultaneously the recognition of these fundamental ethical values and a particular attention to the social and economic conditions that shape the modern lif

alpha_s^3 conversion relation betweeen MS-bar and Euclidean quark masses

We report on the analytical calculation of NNNLO (of order alpha_s^3) conversion factor between the MS-bar quark mass and the one defined in the so-called Regularization Invariant scheme. The NNNLO contribution in the conversion factor turns out to be relatively large and comparable to the known NNLO term.Comment: 4 pages, Latex, uses espcrc2.sty. The paper is also available via anonymous ftp at ftp://ttpux2.physik.uni-karlsruhe.de/ttp99/ttp99-39/ or via www at http://www-ttp.physik.uni-karlsruhe.de/Preprints

Tenth-Order QED Contribution to the Electron g-2 and an Improved Value of the Fine Structure Constant

This paper presents the complete QED contribution to the electron g-2 up to the tenth order. With the help of the automatic code generator, we have evaluated all 12672 diagrams of the tenth-order diagrams and obtained 9.16 (58)(\alpha/\pi)^5. We have also improved the eighth-order contribution obtaining -1.9097(20)(\alpha/\pi)^4, which includes the mass-dependent contributions. These results lead to a_e(theory)=1 159 652 181.78 (77) \times 10^{-12}. The improved value of the fine-structure constant \alpha^{-1} = 137.035 999 174 (35) [0.25 ppb] is also derived from the theory and measurement of a_e.Comment: 4 pages, 2 figures. Some numbers are slightly change