255 research outputs found

    Dimensionally regulated one-loop box scalar integrals with massless internal lines

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    Using the Feynman parameter method, we have calculated in an elegant manner a set of one‚ąí-loop box scalar integrals with massless internal lines, but containing 0, 1, 2, or 3 external massive lines. To treat IR divergences (both soft and collinear), the dimensional regularization method has been employed. The results for these integrals, which appear in the process of evaluating one‚ąí-loop (N‚Č•5)‚ąí(N\ge 5)-point integrals and in subdiagrams in QCD loop calculations, have been obtained for arbitrary values of the relevant kinematic variables and presented in a simple and compact form.Comment: 14 pages, 2 figures included, SVJour, journal versio

    IR finite one-loop box scalar integral with massless internal lines

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    The IR finite one-loop box scalar integral with massless internal lines has been recalculated. The result is very compact, simple and valid for arbitrary values of the relevant kinematic variables. It is given in terms of only two dilogarithms and a few logarithms, all of very simple arguments.Comment: 7 pages, 2 figure

    Absorption of solar radiation by solar neutrinos

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    We calculate the absorption probability of photons radiated from the surface of the Sun by a left-handed neutrino with definite mass and a typical momentum for which we choose |p_1|=0.2 MeV, producing a heavier right-handed antineutrino. Considering two transitions the \nu_1 -> \nu_2 and \nu_2 -> \nu_3 we obtain two oscillation lengths L_{12}=4960.8 m, L_{23}=198.4 m, two absorption probabilities P_{12}^{abs.}=2.5 10^{-67}, P_{23}^{abs.}=1.2 10^{-58} and the two absorption ranges R_{12}^{abs.}=4.47 10^4 R_{\odot}=208.0 au, R_{23}^{abs.}=0.89 10^4 R_{\odot}=41.4 au, using a neutrino mass differences of \sqrt{|\Delta m^2_{12}|}=10 meV, \sqrt{|\Delta m^2_{23}|}=50 meV and associated transition dipole moments. We collect all necessary theoretical ingredients, i.e. neutrino mass and mixing scheme, induced electromagnetic transition dipole moments, quadratic charged lepton mass asymmetries and their interdependence.Comment: 5 pages, 3 figures, typos corrected and reference added, version to appear in Eur. Phys. J.

    De la methexis a la alienación : o el reverso de la libertad

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    El artículo realiza una aproximación a la problemática de un “lugar" filosófico de la libertad y de su génesis. A partir de allí se realiza un recorrido por cuatro autores (Hegel, Marx, Lukács, Honneth) donde se presenta la relación entre libertad y alienación. Este análisis se centra en tres tipos de relación donde se manifiesta el fenómeno de la libertad: relación de sí-consigo, con los otros y con el mundo.Fil: Duplancic, Víctor

    Santiago de Estrada : su viaje al Per√ļ

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    Este trabajo se centra en el estudio de la secci√≥n "De Valpara√≠so a La Oroya", que abarca m√°s de doscientas p√°ginas de las trescientas sesenta y dos del segundo tomo de los Viajes de Santiago Estrada (1889). Se analiza el texto desde la literatura comparada como un texto de viajes en el cual resultan evidentes las constantes antropol√≥gicas y est√©ticas de este tipo de discurso, seg√ļn lo establecen los estudios te√≥ricos al respecto. Desde el punto de vista antropol√≥gico se observa c√≥mo el autor retrata los distintos aspectos de una experiencia viajera corta pero significativa. Desde lo est√©tico se pueden apreciar las estrategias discursivas que ordenan el material de acuerdo con las intenciones panamericanistas del autor y que evidencian su filiaci√≥n rom√°ntica.Fil: Duplancic de Elgueta, Elena. Universidad Nacional de Cuy

    Lattice QCD and QCD Sum Rule determination of the decay constants of eta_c, J/psi and hc states

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    We compute the decay constants of the lowest ccbar-states with quantum numbers J(PC)=0(-+) [eta_c], 1(--) [J/psi], and 1(+-) [hc] by using lattice QCD and QCD sum rules. We consider the coupling of J/psi to both the vector and tensor currents. Lattice QCD results are obtained from the unquenched (Nf=2) simulations using twisted mass QCD at four lattice spacings, allowing us to take the continuum limit. On the QCD sum rule side we use the moment sum rules. The results are then used to discuss the rate of eta_c --> gamma gamma decay, and to comment on the factorization in B --> X K decays, with X being either eta_c or J/psi.Comment: 25 pages (published version
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