8,537 research outputs found
Probing the Standard Model with electroweak penguin B decays
Recent branching fraction and asymmetry results of Electroweak Penguin B
decays from BaBar, Belle and CLEO experiments are reviewed. While these
branching fractions are consistent with the Standard Model expectations and are
being used to extract heavy quark model parameters and CKM matrix elements, the
asymmetry results are just becoming sensitive to observe any new physics
effects.Comment: Invited talk at the XXIII Physics in Collisions Conference (PIC03),
Zeuthen, Germany, June 2003, 12 pages, LaTeX, 3 eps figures. PSN FRAT0
Recommended from our members
Parton distributions
I discuss our current understanding of parton distributions. I begin with the underlying theoretical framework, and the way in which different data sets constrain different partons, highlighting recent developments. The methods of examining the uncertainties on the distributions and those physical quantities dependent on them is analyzed. Finally I look at the evidence that additional theoretical corrections beyond NLO perturbative QCD may be necessary, what type of corrections are indicated and the impact these may have on the uncertainties.</jats:p
Внутрішні аспекти французької безпеки в першу повоєнну добу 1918 – 1924
(uk) У статті розкриваються важливі аспекти безпеки Франції, такі, як зміцнення збройних сил, відновлення національного («священного») союзу, подолання економічних негараздів і соціальної напруженості, використання ресурсів колоній, навколо яких у першу повоєнну добу точилася запекла політична боротьба.(en) The important aspects of safety of France, such as strengthening of military powers, renewal of national («sacred») union, overcoming of economic confusions and social tension, use of resources of colonies open up in the article, round which the bitter political fight proceeded in the first post-war days
Implementation of hidden semi-Markov models
One of the most frequently used concepts applied to a variety of engineering and scientific studies over the recent years is that of a Hidden Markov Model (HMM). The Hidden semi-Markov model (HsMM) is contrived in such a way that it does not make any premise of constant or geometric distributions of a state duration. In other words, it allows the stochastic process to be a semi-Markov chain. Each state can have a collection of observations and the duration of each state is a variable. This allows the HsMM to be used extensively over a range of applications. Some of the most prominent work is done in speech recognition, gene prediction, and character recognition.
This thesis deals with the general structure and modeling of Hidden semi-Markov models and their implementations. It will further show the details of evaluation, decoding, and training with a running example
Persistent Topology of Syntax
We study the persistent homology of the data set of syntactic parameters of
the world languages. We show that, while homology generators behave erratically
over the whole data set, non-trivial persistent homology appears when one
restricts to specific language families. Different families exhibit different
persistent homology. We focus on the cases of the Indo-European and the
Niger-Congo families, for which we compare persistent homology over different
cluster filtering values. We investigate the possible significance, in
historical linguistic terms, of the presence of persistent generators of the
first homology. In particular, we show that the persistent first homology
generator we find in the Indo-European family is not due (as one might guess)
to the Anglo-Norman bridge in the Indo-European phylogenetic network, but is
related to the position of Ancient Greek and the Hellenic branch within the
network.Comment: 15 pages, 25 jpg figure
Measurement of kinematic and nuclear dependence of R = σ_L/σ_T in deep inelastic electron scattering
We report results on a precision measurement of the ratio R=σ_L/σ_T in deep inelastic electron-nucleon scattering in the kinematic range 0.2≤x≤0.5 and 1≤Q^2≤10 (GeV/c)^2. Our results show, for the first time, a clear falloff of R with increasing Q^2. Our R results are in agreement with QCD predictions only when corrections for target mass effects and some additional higher twist effects are included. At small x, the data on R favor structure functions with a large gluon contribution. We also report results on the differences R_A-R_D and the cross section ratio σ^A/σ^D between Fe and Au nuclei and the deuteron. Our results for R_A-R_D are consistent with zero for all x, Q^2 indicating that possible contributions to R from nuclear higher twist effects and spin-0 constituents in nuclei are not different from those in nucleons. The ratios σ^A/σ^D from all recent experiments, at all x, Q^2 values, are now in agreement
Measurement of the Difference in R=σ_L/σ_T and of σ^A/σ^D in Deep-Inelastic e-D, e-Fe, and e-Au Scattering
We measured the differences in R=σ_L/σ_T and the cross-section ratio σA/σD in deep-inelastic electron scattering from D, Fe, and Au nuclei in the kinematic range 0.2≤x≤0.5 and 1≤Q^2≤5 (Gev/c)^2. Our results for R^A-R^D are consistent with zero for all x and Q^2, indicating that possible contributions to R from nuclear higher-twist effects and spin-0 constituents in nuclei are not different from those in nucleons. The European Muon Collaboration effect is reconfirmed, and the low-x data from all recent experiments, at all Q^2, are now in agreement
- …