234 research outputs found

    A geological background for planning and development in the 'Black Country'

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    This study, carried out between 1989 and 1992, was commissioned by the Department of the Environment and funded jointly by the Department and the British Geological Survey. Its principal aim was to produce a synthesis of geological information relevant to the planning of land-use and development in that part of the West Midlands conurbation known as the ‘Black Country’. This report is aimed at those involved in planning and development. The results are presented in a style which, it is hoped, will meet the needs of both those with and without previous geological knowledge. Much of the information is provided on a series of ten thematic maps, each of which concentrates on a specific aspect of the geology relevant to the use of land. In addition to the information contained in the report, sources of other more detailed data are indicated

    Hadron Radiation in Leptonic ZZ Decays

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    The rate for the final state radiation of hadrons in leptonic ZZ decays is evaluated, using as input experimental data for σ(e+e−→hadrons)\sigma (e^+e^-\to hadrons) in the low energy region. Configurations with a lepton pair of large and a hadronic state of low invariant mass are dominant. A relative rate Γllˉhad/Γllˉ=6.3×10−4\Gamma_{l\bar l had}/\Gamma_{l\bar l}=6.3\times 10^{-4} is calculated. This result is about twice the prediction based on a parton model calculation with a quark mass of 300300 MeV. The rate for secondary production of heavy quarks is calculated in the same formalism.Comment: 7 pages, LaTex (uses epsf.sty, 2 figures appended as uuencoded eps files). Errors of some numerical values corrected. Conclusions are not affected by these modification

    Next-to-Next-to-Leading Electroweak Logarithms in W-pair Production at ILC

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    We derive the high energy asymptotic behavior of gauge boson production cross section in a spontaneously broken SU(2) gauge theory in the next-to-next-to-leading logarithmic approximation. On the basis of this result we obtain the logarithmically enhanced two-loop electroweak corrections to the differential cross section of W-pair production at ILC/CLIC up to the second power of the large logarithm.Comment: 17 pages, LaTeX, Eqs. (31) and (35) correcte

    Observing the First Stars and Black Holes

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    The high sensitivity of JWST will open a new window on the end of the cosmological dark ages. Small stellar clusters, with a stellar mass of several 10^6 M_sun, and low-mass black holes (BHs), with a mass of several 10^5 M_sun should be directly detectable out to redshift z=10, and individual supernovae (SNe) and gamma ray burst (GRB) afterglows are bright enough to be visible beyond this redshift. Dense primordial gas, in the process of collapsing from large scales to form protogalaxies, may also be possible to image through diffuse recombination line emission, possibly even before stars or BHs are formed. In this article, I discuss the key physical processes that are expected to have determined the sizes of the first star-clusters and black holes, and the prospect of studying these objects by direct detections with JWST and with other instruments. The direct light emitted by the very first stellar clusters and intermediate-mass black holes at z>10 will likely fall below JWST's detection threshold. However, JWST could reveal a decline at the faint-end of the high-redshift luminosity function, and thereby shed light on radiative and other feedback effects that operate at these early epochs. JWST will also have the sensitivity to detect individual SNe from beyond z=10. In a dedicated survey lasting for several weeks, thousands of SNe could be detected at z>6, with a redshift distribution extending to the formation of the very first stars at z>15. Using these SNe as tracers may be the only method to map out the earliest stages of the cosmic star-formation history. Finally, we point out that studying the earliest objects at high redshift will also offer a new window on the primordial power spectrum, on 100 times smaller scales than probed by current large-scale structure data.Comment: Invited contribution to "Astrophysics in the Next Decade: JWST and Concurrent Facilities", Astrophysics & Space Science Library, Eds. H. Thronson, A. Tielens, M. Stiavelli, Springer: Dordrecht (2008

    Aspects of χ\chi and ψ\psi Production in Polarized Proton-Proton Collisions

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    Several topics of relevance to low transverse momentum ψ\psi and χ1,2(cc‾)\chi_{1,2}(c\overline{c}) production in polarized proton-proton collisions are discussed. The leading O(αS3){\cal O}(\alpha_S^3) contributions to the low pTp_T χ1\chi_1 production cross-sections via gggg, qgqg, and qq‾q\overline{q} initial states are calculated as well as the corresponding spin-spin asymmetries. We find that χ1\chi_1 production increases relative to direct ψ\psi and χ2\chi_2 production, providing up to 25%25\% of the observable e+e−e^+e^- pairs arising from ψ\psi decays in pppp collisions at s=500 GeV\sqrt{s} = 500\,GeV. The spin-dependence of χ1\chi_1 production, however, is much smaller than for either direct ψ\psi or χ2\chi_2 production and so will likely be far less useful than either process in probing the polarized gluon structure function of the proton. A subset of the O(αS3){\cal O}(\alpha_S^3) radiative corrections to χ2\chi_2 production involving initial state quarks are also performed and compared to leading order gg→χ2gg \rightarrow \chi_2 predictions.Comment: 21 pages + 5 postscript figures (included), OCIP/C-94-

    Back the bid: the 2012 summer games and the governance of London

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    The Olympic Park being developed in east London for the 2012 Games is one large urban renewal project among many in the city. The impact of the Games on urban development may be of less significance than the impact on city politics. Bidding for and delivering the Games has contributed to a reassessment of the recent experiment with mayoral government. The paper examines these changing representations of the structures of London government that are now seen as a success. Much of the literature on Olympic cities is highly critical of the impact of the games, but the (current) substantial support for London2012 also needs to be explained. We examine how London has created opportunities for support, and moments and spaces for celebration when political leaders and Londoners can come together around particular representations of themselves and the city

    Physical Processes in Star Formation

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    © 2020 Springer-Verlag. The final publication is available at Springer via https://doi.org/10.1007/s11214-020-00693-8.Star formation is a complex multi-scale phenomenon that is of significant importance for astrophysics in general. Stars and star formation are key pillars in observational astronomy from local star forming regions in the Milky Way up to high-redshift galaxies. From a theoretical perspective, star formation and feedback processes (radiation, winds, and supernovae) play a pivotal role in advancing our understanding of the physical processes at work, both individually and of their interactions. In this review we will give an overview of the main processes that are important for the understanding of star formation. We start with an observationally motivated view on star formation from a global perspective and outline the general paradigm of the life-cycle of molecular clouds, in which star formation is the key process to close the cycle. After that we focus on the thermal and chemical aspects in star forming regions, discuss turbulence and magnetic fields as well as gravitational forces. Finally, we review the most important stellar feedback mechanisms.Peer reviewedFinal Accepted Versio

    Search for gravitational waves from Scorpius X-1 in the second Advanced LIGO observing run with an improved hidden Markov model

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    We present results from a semicoherent search for continuous gravitational waves from the low-mass x-ray binary Scorpius X-1, using a hidden Markov model (HMM) to track spin wandering. This search improves on previous HMM-based searches of LIGO data by using an improved frequency domain matched filter, the J-statistic, and by analyzing data from Advanced LIGO's second observing run. In the frequency range searched, from 60 to 650 Hz, we find no evidence of gravitational radiation. At 194.6 Hz, the most sensitive search frequency, we report an upper limit on gravitational wave strain (at 95% confidence) of h095%=3.47×10-25 when marginalizing over source inclination angle. This is the most sensitive search for Scorpius X-1, to date, that is specifically designed to be robust in the presence of spin wandering. © 2019 American Physical Society
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