36,875 research outputs found

    Double proton tagging at the LHC as a means to discover new physics

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    We review the theoretical and experimental motivations behind recent proposals to add forward proton tagging detectors to the LHC experiments as a means to search for new physics.Comment: Talk given at the 5th Rencontres du Vietnam, 'New Views in Particle Physics' conference, Hanoi, August 200

    Central Exclusive Di-jet Production at the Tevatron

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    We perform a phenomenological analysis of dijet production in double pomeron exchange at the Tevatron. We find that the CDF Run I results do not rule out the presence of an exclusive dijet component, as predicted by Khoze, Martin and Ryskin (KMR). With the high statistics CDF Run II data, we predict that an exclusive component at the level predicted by KMR may be visible, although the observation will depend on accurate modelling of the inclusive double pomeron exchange process. We also compare to the predictions of the DPEMC Monte Carlo, which contains a non-perturbative model for the central exclusive process. We show that the perturbative model of KMR gives different predictions for the di-jet ET dependence in the high di-jet mass fraction region than non-perturbative models.Comment: 17 pages, 15 figure

    Diffractive production of high pt photons at HERA

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    We study the diffractive production of high pt photons at HERA. We have implemented the process as a new hard sub-process in the HERWIG event generator in order to prepare the ground for a future measurement.Comment: 4 pages, 4 figures. Contribution to the 1999 UK Phenomenology Workshop on Collider Physics, Durham, U

    Low-temperature phases in Pb(Zr0.52Ti0.48)O3: A neutron powder diffraction study

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    A neutron powder diffraction study has been carried out on Pb(Zr0.52Ti0.48)O3 in order to resolve an ongoing controversy about the nature of the low-temperature structure of this strongly-piezoelectric and technologically-important material. The results of a detailed and systematic Rietveld analysis at 20 K are consistent with the coexistence of two monoclinic phases having space groups Cm and Ic respectively, in the approximate ratio 4:1, and thus support the findings of a recent electron diffraction study by Noheda et al. [Phys. Rev. B 66, 060103 (2002)]. The results are compared to those of two recent conflicting neutron powder diffraction studies of materials of the same nominal composition by Hatch et al. [Phys. Rev. B 65, 212101 (2002)] and Frantti et al. [Phys. Rev. B 66, 064108 (2002)].Comment: RevTex4, 16 pages, 6 color figure

    Integral Agriculture: Taking seriously the mindset of the farmer, the interiority of the beings on the farm, and a metaphysics that connects them

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    With the steady increase in the market share of organic food over the last 30 years, some farmers have switched from conventional to sustainable agricultural practices in order to capitalize on those new markets. Are the practices the only things that need to change? Building off of Warwick Fox\u27s conception of transpersonal ecology, transpersonal agroecology (TPAE) is the name given to a proposed alternative mindset of the farmer derived from various alternative agricultural theorists of the last 100 years. These writers oppose the scientism and economism that typify industrial agriculture, subscribe to the notion that experiences of identification between the farmer and the beings on the farm are an important component of a truly sustainable agriculture, and suggest that a truly sustainable agriculture requires a radical critique of the metaphysical assumptions that underlie modern agricultural practices. A case is made that a process metaphysics (based on the philosophy of A.N. Whitehead) can productively support a transpersonal agroecological way of being on the farm with its requisite sustainable agricultural practices. Finally, though many theorists have analyzed both industrial and sustainable agriculture from an ideological perspective, most of them partake of a subtle form of materialism, recapitulating the belief that relationships among beings are exclusively external. This subtle materialism precludes the farmer from ascribing interiority to the majority of the beings she is in relationship with. Revisiting transpersonal agroecology, with an understanding of interiority, yields a truly holistic, integral agriculture that takes seriously the mindset of the farmer and the interiority of the beings on the farm

    The Spaceborne Global Climate Observing Center (SGCOC): Executive summary

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    Conceptual planning of the Spaceborne portion of the Global Climate Observing Systems (SGCOS) is reviewed. Fundamentals of the SGCOS are summarized

    Universal Phase Diagram for High-Piezoelectric Perovskite Systems

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    Strong piezoelectricity in the perovskite-type PbZr(1-x)TixO3 (PZT) and Pb(Zn1/3Nb2/3)O3-PbTiO3 (PZN-PT) systems is generally associated with the existence of a morphotropic phase boundary (MPB) separating regions with rhombohedral and tetragonal symmetry. An x-ray study of PZN-9%PT has revealed the presence of a new orthorhombic phase at the MPB, and a near-vertical boundary between the rhombohedral and orthorhombic phases, similar to that found for PZT between the rhombohedral and monoclinic phases. We discuss the results in the light of a recent theoretical paper by Vanderbilt and Cohen, which attributes these low-symmetry phases to the high anharmonicity in these oxide systems.Comment: REVTeX file. 4 pages,=A0 4 figures embedde
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