2,750 research outputs found

    Bilepton Production at Hadron Colliders

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    We examine, as model-independently as possible, the production of bileptons at hadron colliders. When a particular model is necessary or useful, we choose the 3-3-1 model. We consider a variety of processes: q anti-q -> Y^{++} Y^{--}, u anti-d -> Y^{++} Y^{-}, anti-u d -> Y^+ Y^{--}, q anti-q -> Y^{++} e^{-} e^{-}, q anti-q -> phi^{++} phi^{--}, u anti-d -> -> phi^{++} phi^{-}, and anti-u d -> phi^{+} phi^{--}, where Y and phi are vector and scalar bileptons, respectively. Given the present low-energy constraints, we find that at the Tevatron, vector bileptons are unobservable, while light scalar bileptons (M_phi <= 300 GeV) are just barely observable. At the LHC, the reach is extended considerably: vector bileptons of mass M_Y <= 1 TeV are observable, as are scalar bileptons of mass M_phi <= 850 GeV.Comment: 20 pages (LATEX), 7 figures, minor modification

    SOLUTIONS OF THE LANDAU-VLASOV EQUATION IN NUCLEAR PHYSICS

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    The properties of Vlasov equation solutions obtained by projection on coherent state basis are discussed. Such solutions satisfy stationarity conditions and satisfactorily describe the average diffusivity of nuclear phase space and reproduce the bulk properties of nuclei. Sampling methods and their effects on dynamics are discussed for the study of heavy ion reactions at intermediate energies. The non-local Gogny force is easily computable on this basis which allows to use it for dynamical nuclear studies

    LOW AND INTERMEDIATE ENERGY HEAVY ION COLLISIONS IN THE SEMI-CLASSICAL MICROSCOPIC DESCRIPTION

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    It is shown how peripheral and central heavy-ion collisions can be described by Landau-Vlasov dynamics. For peripheral collisions at intermediate energies, mass-mass correlations, ejectile mean energies and angular distributions are obtained and compared with fragmentation data. For central collisions, one shows that the collision term destroys the TDHF property of transparency at low impact parameters for collisions close from the Coulomb barrier. Above 20 MeV/u incomplete fusion is described with associated linear momentum transfer and nuclear deformations. One exhibits how coupling to the continuum is obtained in Vlasov and Landau-Vlasov dynamics. Coulomb interaction being taken into account, we present also results concerning the isospin transfer and the excitation of the isovector dipole mode near and well above the Coulomb barrier. Some perspectives to further studies of physical observables are finally drawn

    Customer Perception of Drive-Thru Service

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    The rapid growth of off-premise dining and, consequently, drive- thru service, presents the challenge of building customer loyalty in a highly competitive marketplace. In this study, customer perceptions of drive-thru service associated with quick service restaurants were examined. Results suggest that service time appears to differ among quick service restaurants, even those within the same chain. Employee courtesy was rated positively at all restaurants, as was food quality. The implications of these results for restaurateurs who offer drive-thru service are discussed

    A STUDY ON THE FUSION REACTION 139La + 12C AT 50 MeV/u WITH THE VUU EQUATION

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    Recently Bownan et al. found that in the reaction 139La + 12C at 50 MeV/u a compound nucleus is formed. We simulate this reaction with a numerical solution of the VUU equation and indeed find that for a central collision the system fuses and equilibrates after 90 fm/c

    Light-particle emission from the fissioning nuclei 126Ba, 188Pt and (266,272,278)/110: theoretical predictions and experimental results

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    We present a comparison of our model treating fission dynamics in conjunction with light-particle (n, p, alpha) evaporation with the available experimental data for the nuclei 126Ba, 188Pt and three isotopes of the element Z=110. The dynamics of the symmetric fission process is described through the solution of a classical Langevin equation for a single collective variable characterizing the nuclear deformation along the fission path. A microscopic approach is used to evaluate the emission rates for pre-fission light particles. Entrance-channel effects are taken into account by generating an initial spin distribution of the compound nucleus formed by the fusion of two deformed nuclei with different relative orientations

    Liquid-Drop Model and Quantum Resistance Against Noncompact Nuclear Geometries

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    The importance of quantum effects for exotic nuclear shapes is demonstrated. Based on the example of a sheet of nuclear matter of infinite lateral dimensions but finite thickness, it is shown that the quantization of states in momentum space, resulting from the confinement of the nucleonic motion in the conjugate geometrical space, generates a strong resistance against such a confinement and generates restoring forces driving the system towards compact geometries. In the liquid-drop model, these quantum effects are implicitly included in the surface energy term, via a choice of interaction parameters, an approximation that has been found valid for compact shapes, but has not yet been scrutinized for exotic shapes.Comment: 9 pages with 3 figure
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