35,142 research outputs found
The saga of bottom production in proton-antiproton collisions
I review here the history of bottom quark cross section measurements and
theoretical predictions. Starting form the early days of UA1, and going through
the sequence of the large excesses reported during run 0 and I at the Tevatron
by CDF and D0, I summarize how both data and theory have evolved in time,
thanks to improved experimental techniques, more data, and improved control
over the main ingredients of the theoretical calculations. I conclude with the
discussion of the preliminary data from run II, which appear to finally give a
satisfactory picture of the data vs theory comparison.Comment: 14 pages, Presented at the 2004 Hadron Collider Physics Workshop,
East Lansing, MI, June 200
Phenomenology of Quarkonium Production in Hadronic Collisions
We review recent progress made in the theory of quarkonium production in
hadronic collisions.Comment: 15 pages, Latex, 6 PS figures included via psfig. To appear in the
Proceedings of the Xth Topical Workshop on Proton--Antiproton Collider
Physics, Batavia, IL, USA, May 199
Observables for possible QGP signatures in central pp collisions
Proton-proton (pp) data show collective effects, such as long-range azimuthal
correlations and strangeness enhancement, which are similar to phenomenology
observed in heavy ion collisions. Using simulations with and without explicit
existing models of collective effects, we explore new ways to probe pp
collisions at high multiplicity, in order to suggest measurements that could
help identify the similarities and differences between large- and small-scale
collective effects. In particular, we focus on the properties of jets produced
in ultra-central pp collisions in association with a Z boson. We consider
observables such as jet energy loss and jet shapes, which could point to the
possible existence of an underlying quark-gluon plasma, or other new dynamical
effects related to the presence of large hadronic densities.Comment: 32 pages, 20 figure
Comments on claimed risk from metastable black holes
In a recent note, arXiv:0808.1415, it was argued that a hypothetical
metastable black hole scenario could pose collider risk not excluded by our
previous study. We comment on inconsistency of this proposed scenario.Comment: 3 pages; comment on arXiv:0808.141
Radiative quarkonium decays and the NMSSM Higgs interpretation of the HyperCP Sigma+ --> p mu+mu- events
We study the potential of radiative decays of the Upsilon(1S) and of the phi
mesons to search for a light pseudoscalar Higgs boson, proposed as a possible
interpretation of Sigma+ --> p mu+mu- events observed by the HyperCP
collaboration at Fermilab. We conclude that the detection of this signal should
certainly be possible with the current CLEO Upsilon(1S) data, and is within the
reach of KLOE in at least part of the range of couplings suggested by the
HyperCP findings.Comment: 6 pages, no figure
Performance based earthquake assessment of an industrial silos structure and retrofit with sliding isolators
Recent seismic events pointed out the high vulnerability of existing industrial facilities, stressing on safety and high losses inherent to interruption of economic activities and release of environmentally hazardous materials. These structures often have irregular geometry and structural configuration, are subject to aging and corrosion, and are designed without specific performance-based or seismic design criteria. Due to these inherent complexities, retrofit using friction isolators can be a viable and practical solution for performance improvements. This work presents a case study of irregular industrial storage plant structure consisting of a group of six elevated silos resting on a steel frame on one side and connected to a vaulted RC structure on the other. A computational model is built incorporating nonlinearities from the components (braces, beams, columns, etc.) and from the mitigation devices. Retrofit using friction isolators is analyzed and evaluated through linear and nonlinear dynamic analyses under a set of natural ground motions. Results show the effectiveness of the mitigation strategy in terms of performance improvement
Lepton Flavour Violating top decays at the LHC
We consider lepton flavour violating decays of the top quark, mediated by
four-fermion operators. We compile constraints on a complete set of
SU(3)*U(1)-invariant operators, arising from their loop contributions to rare
decays and from HERA's single top search. The bounds on e-mu flavour change are
more restrictive than l-tau; nonetheless the top could decay to a jet with a branching ratio of order . We estimate that the
currently available LHC data (20 inverse-fb at 8 TeV) could be sensitive to
+ jet) , and extrapolate that 100
inverse-fb at 13 TeV could reach a sensitivity of .Comment: 10 pages + Appendice
Defining adaptation in a generic multi layer model : CAM: the GRAPPLE conceptual adaptation model
Authoring of Adaptive Hypermedia is a difficult and time consuming task. Reference models like LAOS and AHAM separate adaptation and content in different layers. Systems like AHA! offer graphical tools based on these models to allow authors to define adaptation without knowing any adaptation language. The adaptation that can be defined using such tools is still limited. Authoring systems like MOT are more flexible, but usability of adaptation specification is low. This paper proposes a more generic model which allows the adaptation to be defined in an arbitrary number of layers, where adaptation is expressed in terms of relationships between concepts. This model allows the creation of more powerful yet easier to use graphical authoring tools. This paper presents the structure of the Conceptual Adaptation Models used in adaptive applications created within the GRAPPLE adaptive learning environment, and their representation in a graphical authoring tool
Defining adaptation in a generic multi layer model : CAM: the GRAPPLE conceptual adaptation model
Authoring of Adaptive Hypermedia is a difficult and time consuming task. Reference models like LAOS and AHAM separate adaptation and content in different layers. Systems like AHA! offer graphical tools based on these models to allow authors to define adaptation without knowing any adaptation language. The adaptation that can be defined using such tools is still limited. Authoring systems like MOT are more flexible, but usability of adaptation specification is low. This paper proposes a more generic model which allows the adaptation to be defined in an arbitrary number of layers, where adaptation is expressed in terms of relationships between concepts. This model allows the creation of more powerful yet easier to use graphical authoring tools. This paper presents the structure of the Conceptual Adaptation Models used in adaptive applications created within the GRAPPLE adaptive learning environment, and their representation in a graphical authoring tool
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