58 research outputs found

    Twenty Years of Diffraction at the Tevatron

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    Results on diffractive particle interactions from the Fermilab Tevatron pbar-p collider are placed in perspective through a QCD inspired phenomenological approach, which exploits scaling and factorization properties observed in data. The results discussed are those obtained by the CDF Collaboration from a comprehensive set of single, double, and multigap soft and hard diffraction processes studied during the twenty year period since 1985, when the CDF diffractive program was proposed and the first Blois Workshop was held.Comment: 6 pages, Presented at EDS-2005, XIth International Conference on Elastic and Diffractive Scattering, Chateau de Blois, France, 15-20 May 200

    New Diffraction Results from the Tevatron

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    We present new results from studies on diffractive dijet production and exclusive production of dijet and diphoton obtained by the CDF Collaboration in proton-antiproton collisions at the Fermilab Tevatron.Comment: 4 pages, To be submitted to the proceedings of the 41st Rencontres de Moriond - QCD and High Energy Hadronic Interactions, La Thuile, Italy, 18-25 March 200

    CDF experimental results on diffraction

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    Experimental results on diffraction from the Fermilab Tevatron collider obtained by the CDF experiment are reviewed and compared. We report on the diffractive structure function obtained from dijet production in the range 0<Q2<10,0000<Q^2<10,000 GeV2^2, and on the t|t| distribution in the region 0<t<10<|t<1 GeV2^2 for both soft and hard diffractive events up to Q24,500Q^2\approx 4,500 GeV2^2. Results on single diffractive W/Z production, forward jets, and central exclusive production of both dijets and diphotons are also presented.Comment: 6 pages, 9 figures; Proceedings of the "Multi-Parton Interaction" workshop, Perugia, Italy, October 28-31, 200

    NuGrid stellar data set. 1. Stellar yields from H to Bi for stars with metallicities Z=0.02 and Z=0.01

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    We provide a set of stellar evolution and nucleosynthesis calculations that applies established physics assumptions simultaneously to low- and intermediate-mass and massive star models. Our goal is to provide an internally consistent and comprehensive nuclear production and yield database for applications in areas such as presolar grain studies. Our non-rotating models assume convective boundary mixing (CBM) where it has been adopted before. We include 8 (12) initial masses for Z = 0.01 (0.02). Models are followed either until the end of the asymptotic giant branch phase or the end of Si burning, complemented by simple analytic core-collapse supernova (SN) models with two options for fallback and shock velocities. The explosions show which pre-SN yields will most strongly be effected by the explosive nucleosynthesis. We discuss how these two explosion parameters impact the light elements and the s and p process. For low- and intermediate-mass models, our stellar yields from H to Bi include the effect of CBM at the He-intershell boundaries and the stellar evolution feedback of the mixing process that produces the ¹³C pocket. All post-processing nucleosynthesis calculations use the same nuclear reaction rate network and nuclear physics input. We provide a discussion of the nuclear production across the entire mass range organized by element group. The entirety of our stellar nucleosynthesis profile and time evolution output are available electronically, and tools to explore the data on the NuGrid VOspace hosted by the Canadian Astronomical Data Centre are introduced

    Information Warfare and New Organizational Landscapes: An Inquiry into the ExxonMobil–Greenpeace Dispute over Climate Change

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    A defining characteristic of the emergence of new organizational landscapes is that information is not just being used as a tool by organizations, as it is more usually understood, but also as a weapon in a ?war of position?. As organizations seek to influence public perception over such emotive issues as climate change, conflict at the ideation level can give rise to information warfare campaigns. In this article, we analyse the ways in which ExxonMobil and Greenpeace employ distinctive informational tactics against a range of diverse targets in their dispute over the climate change debate. The purpose of this article is to advance the neo-Gramscian perspective on social movement organizations as a framework for understanding such behaviour. We argue that information warfare is likely to become common as corporations and non-governmental organizations are increasingly sensitive to their informational environment as a source of both opportunity and possible conflict

    Nuclear astrophysics: the unfinished quest for the origin of the elements

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    Half a century has passed since the foundation of nuclear astrophysics. Since then, this discipline has reached its maturity. Today, nuclear astrophysics constitutes a multidisciplinary crucible of knowledge that combines the achievements in theoretical astrophysics, observational astronomy, cosmochemistry and nuclear physics. New tools and developments have revolutionized our understanding of the origin of the elements: supercomputers have provided astrophysicists with the required computational capabilities to study the evolution of stars in a multidimensional framework; the emergence of high-energy astrophysics with space-borne observatories has opened new windows to observe the Universe, from a novel panchromatic perspective; cosmochemists have isolated tiny pieces of stardust embedded in primitive meteorites, giving clues on the processes operating in stars as well as on the way matter condenses to form solids; and nuclear physicists have measured reactions near stellar energies, through the combined efforts using stable and radioactive ion beam facilities. This review provides comprehensive insight into the nuclear history of the Universe and related topics: starting from the Big Bang, when the ashes from the primordial explosion were transformed to hydrogen, helium, and few trace elements, to the rich variety of nucleosynthesis mechanisms and sites in the Universe. Particular attention is paid to the hydrostatic processes governing the evolution of low-mass stars, red giants and asymptotic giant-branch stars, as well as to the explosive nucleosynthesis occurring in core-collapse and thermonuclear supernovae, gamma-ray bursts, classical novae, X-ray bursts, superbursts, and stellar mergers.Comment: Invited Review. Accepted for publication in "Reports on Progress in Physics" (version with low-resolution figures
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