2,391 research outputs found

    Parity-Violating Electron Scattering and Neucleon Structure

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    The measurement of parity violation in the helicity dependence of electron-nucleon scattering provides unique information about the basic quark structure of the nucleons. In this review, the general formalism of parity-violating electron scattering is presented, with emphasis on elastic electron-nucleon scattering. The physics issues addressed by such experiments is discussed, and the major goals of the presently envisioned experimental program are identified. %General aspects of the experimental technique are reviewed and A summary of results from a recent series of experiments is presented and the future prospects of this program are also discussed.Comment: 45 pages, 9 figure

    Garvey-Kelson Relations for Nuclear Charge Radii

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    The Garvey-Kelson relations (GKRs) are algebraic expressions originally developed to predict nuclear masses. In this letter we show that the GKRs provide a fruitful framework for the prediction of other physical observables that also display a slowly-varying dynamics. Based on this concept, we extend the GKRs to the study of nuclear charge radii. The GKRs are tested on 455 out of the approximately 800 nuclei whose charge radius is experimentally known. We find a rms deviation between the GK predictions and the experimental values of only 0.01 fm. This should be contrasted against some of the most successful microscopic models that yield rms deviations almost three times as large. Predictions - with reliable uncertainties - are provided for 116 nuclei whose charge radius is presently unknown.Comment: 4 pages and 3 figure

    Error propagation in extrapolated nuclear mass predictions

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    The properties of the error of the nuclear masses calculated from the transverse mass relations are analysed. The work assumes that the calculated errors of the nuclei whose masses are known experimentally behave as a sample selected randomly from a normal population having a zero mean and a standard deviation σ . It is found that the errors of the calculated masses of nuclei far from the line of beta-stability behave as c 1 d 3/2 where c 1 is a constant and d is the distance of the nucleus from the line of beta-stability. It is shown also that the errors related to the calculated mass differences behave as c 2 d 1/2 where c 2 is another constant.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45826/1/10050_2005_Article_BF01433618.pd

    Signals for strange quark contributions to the neutrino (antineutrino) scattering in quasi-elastic region

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    Strange quark contributions to the neutrino (antineutrino) scattering are investigated on the elastic neutrino-nucleon scattering and the neutrino-nucleus scattering for 12C target in the quasi-elastic region on the incident energy of 500 MeV, within the framework of a relativistic single particle model. For the neutrino-nucleus scattering, the effects of final state interaction for the knocked-out nucleon are included by a relativistic optical potential. In the cross sections we found some cancellations of the strange quark contributions between the knocked-out protons and neutrons. Consequently, the asymmetries between the incident neutrino and antineutrino which is the ratio of neutral current to charged current, and the difference between the asymmetries are shown to be able to yield more feasible quantities for the strangeness effects. In order to explicitly display importance of the cancellations, results of the exclusive reaction 16O(\nu, \nu' p) are additionally presented for detecting the strangeness effects.Comment: 14 pages, 8 figures, submitted to Phys. Lett.

    "Driven to distraction?" Children's experiences of car travel

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    This is an Author's Accepted Manuscript of an article published in volume, 4, issue 1, pages 59-76 in Mobilities 2009. Copyright @ 2009 Taylor & Francis, available online at: http://www.tandfonline.com/doi/abs/10.1080/17450100802657962.Cars have become increasingly significant features in the lives of many children and adults in the UK and elsewhere. Whilst there is a growing body of research considering how adults experience automobility, that is the increasingly central role of cars within societies, there has been little equivalent research exploring children's perspectives. Drawing upon a variety of methods including personal diaries, photographs, in‐depth interviews and surveys amongst schools within Buckinghamshire and North London, the paper contributes to filling this gap in existing research through exploring how cars are not only journey spaces for children, but are also sites for play, relaxation, homework, companionship, technology and the consumption of commodities. Using a Foucauldian analysis of power, insights into wider familial processes relating to mobility are provided by exploring how cars are sites of conflicting power relations between parents and children. The paper also explores how children's everyday experiences of cars were framed by wider sets of power relations, including car corporations which design and manufacture these spaces, and the role of capital which commodifies everyday activities in cars. In doing so, the paper challenges existing research on automobility for only focusing upon adults' experiences of cars and begins to theorise a more inclusive account of automobility which incorporates children and young people

    Exchange Current Corrections to Neutrino--Nucleus Scattering

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    Relativistic exchange current corrections to neutrino--nucleus cross sections are presented assuming non--vanishing strange quark form factors for the constituent nucleons. For charged current processes the exchange current corrections can lower the impulse approximation results by 10\% while these corrections are found to be sensitive to both the nuclear density and the strange quark axial form factor of the nucleon for neutral current processes. Implications on the LSND experiment to determine this form factor are discussed.Comment: 11 pages, 2 figures, revtex 3.0, full postscript version of the file and figures available at http://www.nikhefk.nikhef.nl/projects/Theory/preprints/preprints.html To appear in Phys. Rev. Lett

    Strange Mesonic Transition Form Factor in the Chiral Constituent Quark Model

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    The form factor gρπ(S)(Q2)g_{\rho \pi}^{(S)}(Q^{2}) of the strange vector current transition matrix element is calculated within the chiral quark model. A strange vector current of the constituent UU- and D-quarks is induced by kaon radiative corrections and this mechanism yields the nonvanishing values of gρπ(S)(0)g_{\rho\pi}^{(S)}(0). The numerical result at the photon point is consistent with the one given by the ϕ\phi -meson dominance model, but the fall-off in the Q2Q^{2}-dependence is faster than the monopole form factor. Mesonic radiative corrections are also examined for the electromagnetic ρ\rho -to-π\pi and K∗K^{*}-to-KK transition amplitudes.Comment: LaTex 11 pages, 2 PostScript figure

    A Letter of Intent to Build a MiniBooNE Near Detector: BooNE

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    There is accumulating evidence for a difference between neutrino and antineutrino oscillations at the ∌1\sim 1 eV2^2 scale. The MiniBooNE experiment observes an unexplained excess of electron-like events at low energies in neutrino mode, which may be due, for example, to either a neutral current radiative interaction, sterile neutrino decay, or to neutrino oscillations involving sterile neutrinos and which may be related to the LSND signal. No excess of electron-like events (−0.5±7.8±8.7-0.5 \pm 7.8 \pm 8.7), however, is observed so far at low energies in antineutrino mode. Furthermore, global 3+1 and 3+2 sterile neutrino fits to the world neutrino and antineutrino data suggest a difference between neutrinos and antineutrinos with significant (sin⁥22ΞΌΌ∌35\sin^22\theta_{\mu \mu} \sim 35%) ΜˉΌ\bar \nu_\mu disappearance. In order to test whether the low-energy excess is due to neutrino oscillations and whether there is a difference between ΜΌ\nu_\mu and ΜˉΌ\bar \nu_\mu disappearance, we propose building a second MiniBooNE detector at (or moving the existing MiniBooNE detector to) a distance of ∌200\sim 200 m from the Booster Neutrino Beam (BNB) production target. With identical detectors at different distances, most of the systematic errors will cancel when taking a ratio of events in the two detectors, as the neutrino flux varies as 1/r21/r^2 to a calculable approximation. This will allow sensitive tests of oscillations for both Îœe\nu_e and Μˉe\bar \nu_e appearance and ΜΌ\nu_\mu and ΜˉΌ\bar \nu_\mu disappearance. Furthermore, a comparison between oscillations in neutrino mode and antineutrino mode will allow a sensitive search for CP and CPT violation in the lepton sector at short baseline (Δm2>0.1\Delta m^2 > 0.1 eV2^2).Comment: 43 pages, 40 figure
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