1,721,183 research outputs found
Radiative penguin and leptonic rare decays at BABAR.
No full textRecent BaBar results on rare B decays involving flavour-changing neutral currents or purely leptonic final states are presented. New measurements of the CP asymmetries in B -> K* gamma, B -> K*2(1430) gamma, and b -> s gamma are reported, as well as a new measurement of the B -> K* gamma branching fraction. Also reported are updated limits on B -> mu nu and recent measurements of B -> K* l+ l- and b -> s l+ l-. The data sample comprises 123 10^6 Y4S -> B Bbar decays collected with the BaBar detector at the PEP-II e+e- storage ring
SuperB Progress Reports -- Accelerator
No full textAbstract: The physics objectives of SuperB, an asymmetric electron-positron collider with a luminosity above 10^36/cm^2/s are described, together with the conceptual design of a novel low emittance design that achieves this performance with wallplug power comparable to that of the current B Factories, and an upgraded detector capable of doing the physics in the SuperB environment
Touschek effect at DAFNE for the new KLOE run in the crab-waist scheme.
No full textThe innovative crab-waist collision scheme has been recently implemented at DAFNE for a new KLOE run. This scheme requires special attention to the Touschek effect, both for the lifetime and the machine induced backgrounds into the detector. T hese two aspects have been handled starting from the same Monte Carlo simulation. The DAFNE optical model has been tuned to keep the effects of Touschek scattering under control with a trade-off between critical parameters, following the indications given by simulations. Connections between numerical results and lattice modifications are discussed here. Dedicated lifetime measurements have been carried out to validate these studies. Particle losses at the IR have been minimized by means of the same optica l knobs, but in addition proper shieldings have been implemented to further decrease their impact on the detector performance. IR distributions of the Touschek particle losses have been tracked from the beam pipe into KLOE for direct comparison of measure d and expected backgrounds. Moreover, these studies are carried out with the same software tools used for the SuperB factory design, allowing a direct validation test of this approach
MAGNETIC DESIGN STUDIES FOR THE FINAL FOCUS QUADRUPOLES OF THE SUPERB LARGE CROSSING ANGLE COLLISION SCHEME
No full textThe final doublets of the SuperB factory project [1], based on the large crossing angle collision scheme, must provide a pure quadrupolar field on each of the two beams to avoid the high background rates in the detector
Design, Construction and Test of a Model Superconducting Quadrupole for the Interaction Region of Super B Factory
No full textSuper is an asymmetric energy e(+)e(-) collider operating at the gamma(4S) peak (root s similar to 10.58 GeV) to be built in Italy, with a design peak luminosity of 10(36) Hz/cm(2). In order to get the required high luminosity, a novel collision scheme, the so called "large Piwinski angle and crab waist", has been designed. This scheme requires that two doublets of high gradient superconducting quadrupoles (denominated in the Super naming scheme as QD0 and QF1) are placed as close as possible to the interaction point. This layout is critical because the space allowed to the doublets is very small. An advanced design of the quadrupole has been developed, based on the so-called helical coil concept. The paper discusses the design and construction concept of a model of the superconducting quadrupole based on NbTi technology
Compact Superconducting High Gradient Quadrupole Magnets for the Interaction Regions of High Luminosity Colliders
No full textRecent developments in the high luminosity e(+)e(-) colliders are based on a collision scheme with a large Piwinski angle, a vertical beta function beta(y) much smaller than the bunch length, and a crab waist transformation. This scheme is being adopted in the SuperB asymmetric collider, to be built in Italy, with a design peak luminosity of 10(36) cm(-2) sec(-1). A crucial role is played by the quadrupole doublets QD0/QF1, which are placed close to the interaction point and generate gradients close to 100 T/m. The available space for the doublets is very small, causing the magnets to be operated with a high engineering current density (2000 A/mm(2)). Starting from the helical coil concept, an advanced design of the quadrupole has been developed. The paper discusses the basic design concepts and the development of a coil model aimed at assessing the design criteria and demonstrating the feasibility of the quadrupole. The successful test of the coil model opens the way to new compact superconducting high gradient quadrupole magnets for the interaction regions of high luminosity colliders
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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