5,988 research outputs found

    Detection of atmospheric neutrinos and relativistic nuclear structure effects

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    Neutrino-nucleus cross sections for the detection of atmospheric neutrinos are calculated in relativistic impulse and random phase approximations. Pion production is estimated via inclusive Delta-hole nuclear excitations. The number of pion events can confuse the identification of the neutrino flavor. As a further source of pions we calculate coherent pion production (where the nucleus remains in the ground state). We examine how these nuclear structure effects influence atmospheric neutrino experiments and study possible improvements in the present detector simulations

    Aging effects in the quantum dynamics of a dissipative free particle: non-ohmic case

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    We report new results related to the two-time dynamics of the coordinate of a quantum free particle, damped through its interaction with a fractal thermal bath (non-ohmic coupling ∼ωδ\sim\omega^\delta with 0<δ<10<\delta<1 or 1<δ<2)1<\delta<2). When the particle is localized, its position does not age. When it undergoes anomalous diffusion, only its displacement may be defined. It is shown to be an aging variable. The finite temperature aging regime is self-similar. It is described by a scaling function of the ratio tw/τ{t_w/\tau} of the waiting time to the observation time, as characterized by an exponent directly linked to δ\delta.Comment: 4 pages, 3 figures, submitted to PR

    The acute effects of daily nicotine intake on heart rate--a toxicokinetic and toxicodynamic modelling study.

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    Abstract Joint physiologically-based toxicokinetic and toxicodynamic (PBTK/TD) modelling was applied to simulate concentration–time profiles of nicotine, a well-known stimulant, in the human body following single and repeated dosing. Both kinetic and dynamic models were first calibrated by using in vivo literature data for the Caucasian population. The models were then used to estimate the blood and liver concentrations of nicotine in terms of the Area Under Curve (AUC) and the peak concentration (Cmax) for selected exposure scenarios based on inhalation (cigarette smoking), oral intake (nicotine lozenges) and dermal absorption (nicotine patches). The model simulations indicated that whereas frequent cigarette smoking gives rise to high AUC and Cmax in blood, the use of nicotine-rich dermal patches leads to high AUC and Cmax in the liver. Venous blood concentrations were used to estimate one of the most common acute effects, mean heart rate, both at rest and during exercise. These estimations showed that cigarette smoking causes a high peak heart rate, whereas dermal absorption causes a high mean heart rate over 48 h. This study illustrates the potential of using PBTK/TD modelling in the safety assessment of nicotine-containing products

    Production of eta Mesons in Double Pomeron Exchange

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    We estimate the production cross sections for ηc\eta_c and ηb\eta_b mesons via pomeron-pomeron fusion in peripheral heavy-ion collisions. Total and elastic PP cross sections are calculated in an equivalent pomeron approximation.Comment: 9 pages, 3 Postscript figure

    Precision Spectroscopy at Heavy Ion Ring Accelerator SIS300

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    Unique spectroscopic possibilities open up if a laser beam interacts with relativistic lithium-like ions stored in the heavy ion ring accelerator SIS300 at the future Facility for Antiproton and Ion Research FAIR in Darmstadt, Germany. At a relativistic factor gamma = 36 the 2P 1/2 level can be excited from the 2S 1/2 ground state for any element with frequency doubled dye-lasers in collinear geometry. Precise transition energy measurements can be performed if the fluorescence photons, boosted in forward direction into the X-ray region, are energetically analyzed with a single crystal monochromator. The hyperfine structure can be investigated at the 2P 1/2 - 2S 1/2 transition for all elements and at the 2P 3/2 - 2S 1/2 transition for elements with Z < 50. Isotope shifts and nuclear moments can be measured with unprecedented precision, in principle even for only a few stored radioactive species with known nuclear spin. A superior relative line width in the order of 5E-7 may be feasible after laser cooling, and even polarized external beams may be prepared by optical pumping

    On the temperature dependence of correlation functions in the space like direction in hot QCD

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    We study the temperature dependence of quark antiquark correlations in the space like direction. In particular, we predict the temperature dependence of space like Bethe-Salpeter amplitudes using recent Lattice gauge data for the space like string potential. We also investigate the effect of the space like string potential on the screening mass and discuss possible corrections which may arise when working with point sources.Comment: 15 pages 8 figures (not included, will be sent on request), (SUNY-NTG-94-3

    On the Red-Green-Blue Model

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    We experimentally study the red-green-blue model, which is a sytem of loops obtained by superimposing three dimer coverings on offset hexagonal lattices. We find that when the boundary conditions are ``flat'', the red-green-blue loops are closely related to SLE_4 and double-dimer loops, which are the loops formed by superimposing two dimer coverings of the cartesian lattice. But we also find that the red-green-blue loops are more tightly nested than the double-dimer loops. We also investigate the 2D minimum spanning tree, and find that it is not conformally invariant.Comment: 4 pages, 7 figure

    Exact Multifractal Spectra for Arbitrary Laplacian Random Walks

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    Iterated conformal mappings are used to obtain exact multifractal spectra of the harmonic measure for arbitrary Laplacian random walks in two dimensions. Separate spectra are found to describe scaling of the growth measure in time, of the measure near the growth tip, and of the measure away from the growth tip. The spectra away from the tip coincide with those of conformally invariant equilibrium systems with arbitrary central charge c≤1c\leq 1, with cc related to the particular walk chosen, while the scaling in time and near the tip cannot be obtained from the equilibrium properties.Comment: 4 pages, 3 figures; references added, minor correction

    Glueball Production in Peripheral Heavy-Ion Collisions

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    The method of equivalent quanta is applied both to photon-photon and, by analogy, to double pomeron exchange in heavy-ion collisions. This Weizs\"acker-Williams approach is used to calculate production cross sections for the glueball candidate fJ(1710)f_J(1710) meson via photon-photon and pomeron-pomeron fusion in peripheral heavy-ion collisions at both RHIC and LHC energies. The impact-parameter dependence for total and elastic cross sections are presented, and are compared to results for proton-proton collisions.Comment: 15 pages, 6 figure
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