58 research outputs found
Twenty Years of Diffraction at the Tevatron
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
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
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
GeV, and on the distribution in the region
GeV for both soft and hard diffractive events up to
GeV. 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
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
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Measurement of total cross sections on hydrogen and deuterium
Total cross sections of {pi}{sup {+-}}, K{sup {+-}}, p and {bar p} on hydrogen and deuterium are to be measured at about eight energies between 20 GeV and the maximum available energy. An accuracy of about one part in one thousand will yield the energy dependence of cross sections, comparisons of cross sections within SU(3) supermultiplets, and stringent tests of high energy limiting theorems
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Tevatron-for-LHC Report of the QCD Working Group
The experiments at Run 2 of the Tevatron have each accumulated over 1 fb{sup -1} of high-transverse momentum data. Such a dataset allows for the first precision (i.e. comparisons between theory and experiment at the few percent level) tests of QCD at a hadron collider. While the Large Hadron Collider has been designed as a discovery machine, basic QCD analyses will still need to be performed to understand the working environment. The Tevatron-for-LHC workshop was conceived as a communication link to pass on the expertise of the Tevatron and to test new analysis ideas coming from the LHC community. The TeV4LHC QCD Working Group focused on important aspects of QCD at hadron colliders: jet definitions, extraction and use of Parton Distribution Functions, the underlying event, Monte Carlo tunes, and diffractive physics. This report summarizes some of the results achieved during this workshop
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Measurement of the top quark mass using the template method in the lepton plus jets channel with in situ W ---> j j calibration at CDF-II
We report an updated measurement of the top quark mass in the lepton plus jets channel of t{bar t} events from p{bar p} collisions at {radical}s = 1.96 TeV. This measurement uses a dataset with integrated luminosity of 680 pb{sup -1}, containing 360 t{bar t} candidates separated into four subsamples. A top quark mass is reconstructed for each event by using energy and momentum constraints on the top quark pair decay products. We also employ the reconstructed mass of hadronic W boson decays W {yields} jj to constrain in situ the largest systematic uncertainty of the top quark mass measurement: the jet energy scale. Monte Carlo templates of the reconstructed top quark and W boson mass are produced as a function of the true top quark mass and the jet energy scale. The distribution of reconstructed top quark and W boson mass in the data are compared to the Monte Carlo templates using a likelihood fit to obtain: M{sub top} = 173.4 {+-} 2.8 GeV/c{sup 2}
Information Warfare and New Organizational Landscapes: An Inquiry into the ExxonMobil–Greenpeace Dispute over Climate Change
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
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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