1,060 research outputs found
Pipeline Geopolitics: Subaquatic Materials and the Tactical Point
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 âtactical pointâ 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
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
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
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
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
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
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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