1,050 research outputs found

    Pipeline Geopolitics: Subaquatic Materials and the Tactical Point

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    This paper starts from the proposition that studies of geopolitics need to address the political significance of spaces above and below the apparently twodimensional or flat surface of the land and sea. However, we depart from the view that such spaces should be defined by their verticality or conceived as three-dimensional volumes. Instead, the argument stresses the importance of attending to the relations between physical and biological things, and the ways in which the proximity of things is both mediated and supplemented by legal, and scientific and political practice. The empirical focus of the paper is a specific geopolitical puzzle. How did a short section of the route of a transnational gas pipeline, the 3500km Southern Gas Corridor, come to be a site or ‘tactical point’ at which the construction of the pipeline could be disrupted? Our contention is that any analysis of this political question must address not only the contested relations between states, corporations and civil society, but also the potential tension and interference between the horizontal networked geopolitics of pipelines and their subaquatic and subterranean construction. The subaquatic turns out not to be volume but a space of situated encounters between disparate materials

    Recent developments in radiative B decays

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    We report on recent theoretical progress in radiative B decays. We focus on a calculation of logarithmically enhanced QED corrections to the branching ratio and forward-backward asymmetry in the inclusive rare decay anti-B --> X(s) l+ l-, and present the results of a detailed phenomenological analysis. We also report on the calculation of NNLO QCD corrections to the inclusive decay anti-B --> X(s) gamma. As far as exclusive modes are concerned we consider transversity amplitudes and the impact of right-handed currents in the exclusive anti-B --> K^* l+ l- decay. Finally, we state results for exclusive B --> V gamma decays, notably the time-dependent CP-asymmetry in the exclusive B --> K^* gamma decay and its potential to serve as a so-called ``null test'' of the Standard Model, and the extraction of CKM and unitarity triangle parameters from B --> (rho,omega) gamma and B --> K^* gamma decays.Comment: 5 pages, 2 figures. Accepted for publication in the proceedings of International Europhysics Conference on High Energy Physics (EPS-HEP2007), Manchester, England, 19-25 Jul 200

    Complete NNLO QCD Analysis of B -> X_s l^+ l^- and Higher Order Electroweak Effects

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    We complete the next-to-next-to-leading order QCD calculation of the branching ratio for B -> X_s l^+ l^- including recent results for the three-loop anomalous dimension matrix and two-loop matrix elements. These new contributions modify the branching ratio in the low-q^2 region, BR_ll, by about +1% and -4%, respectively. We furthermore discuss the appropriate normalization of the electromagnetic coupling alpha and calculate the dominant higher order electroweak effects, showing that, due to accidental cancellations, they change BR_ll by only -1.5% if alpha(mu) is normalized at mu = O(m_b), while they shift it by about -8.5% if one uses a high scale normalization mu = O(M_W). The position of the zero of the forward-backward asymmetry, q_0^2, is changed by around +2%. After introducing a few additional improvements in order to reduce the theoretical error, we perform a comprehensive study of the uncertainty. We obtain BR_ll(1 GeV^2 <= q^2 <= 6 GeV^2) = (1.57 +- 0.16) x 10^-6 and q_0^2 = (3.76 +- 0.33) GeV^2 and note that the part of the uncertainty due to the b-quark mass can be easily reduced.Comment: 26 pages, 7 figures; v5: corrected normalisation in Eq. (5), numerical results unchange

    Physical renormalization condition for the quark-mixing matrix

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    We investigate the renormalization of the quark-mixing matrix in the Electroweak Standard Model. We show that the corresponding counterterms must be gauge independent as a consequence of extended BRS invariance. Using rigid SU(2)_L symmetry, we proof that the ultraviolet-divergent parts of the invariant counterterms are related to the field renormalization constants of the quark fields. We point out that for a general class of renormalization schemes rigid SU(2)_L symmetry cannot be preserved in its classical form, but is renormalized by finite counterterms. Finally, we discuss a genuine physical renormalization condition for the quark-mixing matrix that is gauge independent and does not destroy the symmetry between quark generations.Comment: 20 pages, LaTeX, minor changes, references adde

    Brief review on semileptonic B decays

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    We concisely review semileptonic B decays, focussing on recent progress on both theoretical and experimental sides.Comment: 18 pages, 2 figures; version to be published in Mod. Phys. Lett.

    A New Renormalization Scheme of Fermion Fields in Electroweak Standard Model

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    This paper has been withdrawn by the author,due a immature idea.Comment: 6 page

    QCD Corrections to the Radiative Decay B -> X_s gamma

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    In this short review, the calculation of the next-to-next-to-leading order QCD corrections to the inclusive radiative decay B -> X_s gamma is described. I summarize the salient features of the calculational framework adopted, discuss the results obtained in the last few years, and indicate the technical tools that made the NNLO calculations possible. I conclude by comparing the current NNLO theoretical estimate for the branching ratio with the experimental measurement and by briefly discussing the size and origin of the residual theoretical uncertainty.Comment: 18 pages, 7 figures. Invited review for Modern Physics Letters
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