174 research outputs found
Towards the NNLL precision in
The present NLL prediction for the decay rate of the rare inclusive process
has a large uncertainty due to the charm mass
renormalization scheme ambiguity. We estimate that this uncertainty will be
reduced by a factor of 2 at the NNLL level. This is a strong motivation for the
on-going NNLL calculation, which will thus significantly increase the
sensitivity of the observable to possible new degrees
of freedom beyond the SM. We also give a brief status report of the NNLL
calculation.Comment: 5 pages, 2 figures, contribution to the proceedings of EPS-HEP 200
Reduction of Charm Quark Mass Scheme Dependence in at the NNLL Level
The uncertainty of the theoretical prediction of the
branching ratio at NLL level is dominated by the charm mass renormalization
scheme ambiguity. In this paper we calculate those NNLL terms which are related
to the renormalization of , in order to get an estimate of the
corresponding uncertainty at the NNLL level. We find that these terms
significantly reduce (by typically a factor of two) the error on induced by the definition of . Taking into account the
experimental accuracy of around 10% and the future prospects of the
factories, we conclude that a NNLL calculation would increase the sensitivity
of the observable to possible new degrees of freedom
beyond the SM significantly.Comment: 13 pages including 3 figure
Reconciling scientific reality with realpolitik: moving beyond carbon pricing to TEQs – an integrated, economy-wide emissions cap
<div><p>This article considers why price-based frameworks may be inherently unsuitable for delivering unprecedented global emissions reductions while retaining the necessary public and political support, and argues that it is time to instead draw on quantity-based mechanisms such as TEQs (tradable energy quotas).</p><p>TEQs is a climate policy framework combining a hard cap on emissions with the use of market mechanisms to distribute quotas beneath that cap.</p><p>The significant international research into TEQs is summarized, including a 2008 UK government feasibility study, which concluded that the scheme was “ahead of its time.” TEQs would cover all sectors within a national economy, including households, and findings suggest it could act as a catalyst for the socio-technical transitions required to maximize wellbeing under a tightening cap, while generating national common purpose toward innovative energy demand reductions.</p><p>Finally, there are reflections on the role that the carbon management community can play in further developing TEQs and reducing the rift between what climate science calls for and what politics is delivering.</p></div
Non-Canonical Perturbation Theory of Non-Linear Sigma Models
We explore the O(N)-invariant Non-Linear Sigma Model (NLSM) in a different
perturbative regime from the usual relativistic-free-field one, by using
non-canonical basic commutation relations adapted to the underlying O(N)
symmetry of the system, which also account for the non-trivial (non-flat)
geometry and topology of the target manifold.Comment: 11 pages, 1 figure, LaTe
NNLL QCD Contribution of the Electromagnetic Dipole Operator to Gamma(anti-B -> X(s) gamma)
We present an independent calculation of that part of the O(\alpha_s^2)
contribution to the decay width \Gamma(\bar B -> X_s \gamma) which arises from
the self-interference term of the electromagnetic dipole operator O_7. Using a
different method, we find complete agreement with a previous calculation. This
NNLL contribution is an important ingredient for the complete NNLL prediction
of \Gamma(\bar B -> X_s \gamma) which will resolve the charm quark mass
ambiguity appearing at NLL accuracy.Comment: 15 pages, uses axodraw.st
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