237,066 research outputs found

    Analytical methods in heavy quark physics and the case of τ1/2(w)\tau_{1/2}(w)

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    Analytical methods in heavy quark physics are shortly reviewed, with emphasis on the problems of dynamical calculations. Then, attention is attracted to the various difficulties raised by a tentative experimental determination of τ1/2\tau_{1/2}Comment: 10 pages, FPCP2003 conference (Paris) [typos corrected,new references

    From the arrow of time in Badiali's quantum approach to the dynamic meaning of Riemann's hypothesis

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    The novelty of the Jean Pierre Badiali last scientific works stems to a quantum approach based on both (i) a return to the notion of trajectories (Feynman paths) and (ii) an irreversibility of the quantum transitions. These iconoclastic choices find again the Hilbertian and the von Neumann algebraic point of view by dealing statistics over loops. This approach confers an external thermodynamic origin to the notion of a quantum unit of time (Rovelli Connes' thermal time). This notion, basis for quantization, appears herein as a mere criterion of parting between the quantum regime and the thermodynamic regime. The purpose of this note is to unfold the content of the last five years of scientific exchanges aiming to link in a coherent scheme the Jean Pierre's choices and works, and the works of the authors of this note based on hyperbolic geodesics and the associated role of Riemann zeta functions. While these options do not unveil any contradictions, nevertheless they give birth to an intrinsic arrow of time different from the thermal time. The question of the physical meaning of Riemann hypothesis as the basis of quantum mechanics, which was at the heart of our last exchanges, is the backbone of this note.Comment: 13 pages, 2 figure

    Sum rules in the heavy quark limit of QCD

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    In the leading order of the heavy quark expansion, we propose a method within the OPE and the trace formalism, that allows to obtain, in a systematic way, Bjorken-like sum rules for the derivatives of the elastic Isgur-Wise function ξ(w)\xi(w) in terms of corresponding Isgur-Wise functions of transitions to excited states. A key element is the consideration of the non-forward amplitude, as introduced by Uraltsev. A simplifying feature of our method is to consider currents aligned along the initial and final four-velocities. As an illustration, we give a very simple derivation of Bjorken and Uraltsev sum rules. On the other hand, we obtain a new class of sum rules that involve the products of IW functions at zero recoil and IW functions at any ww. Special care is given to the needed derivation of the projector on the polarization tensors of particles of arbitrary integer spin. The new sum rules give further information on the slope ρ2=ξ(1)\rho^2 = - \xi '(1) and also on the curvature σ2=ξ(1)\sigma^2 = \xi '' (1), and imply, modulo a very natural assumption, the inequality σ254ρ2\sigma^2 \geq {5\over 4} \rho^2, and therefore the absolute bound σ21516\sigma^2 \geq {15 \over 16}.Comment: 64 pages, Late

    Designing Redress: A Study About Grievances Against Public Bodies

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    How grievances against public bodies are resolved is important not only for the individuals concerned and the decision-makers complained about but also to the whole system of government. People need to have confidence that when things go wrong, they will be put right. There is a general public interest in that being done in accordance with constitutional principles and in ways that are effective and efficient. Over many years, a great variety of different ?mechanisms? for dealing with grievances have been created, ranging from internal complaints processes through to the work of external bodies (including ombudsmen, tribunals and courts). This project has focused on how mechanisms are designed. The study explores how different mechanisms can be thought of as relating to each other. It also looks at the various reasons why mechanisms have to be designed. Drawing on interviews with people involved in the design process and analysis of public information, a map of where the activity of designing redress has been created. Evaluating the ?administrative justice landscape?, two particular deficiencies emerge: there is no strong political or official leadership in relation to how mechanisms ought to be designed and the system is fragmented, with many different people, in various organisations all contributing to design activities. Might a toolkit of guiding principles for designing redress be one way of achieving a better design process and outcomes? A number of principles are proposed in this report, and the authors hope to engage stakeholders in a debate about how this might best be taken forward

    Study of thermometers for measuring a microcanonical phase transition in nuclear fragmentation

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    The aim of this work is to study how the thermodynamic temperature is related to the known thermometers for nuclei especially in view of studying the microcanonical phase transition. We find within the MMMC-model that the "S-shape" of the caloric equation of state e^*(T) which is the signal of a phase transition in a system with conserved energy, can be seen in the experimentally accessible slope temperatures T_slope for different particle types and also in the isotopic temperatures T_He-Li. The isotopic temperatures T_H-He are weaker correlated to the shape of the thermodynamic temperature and therefore are less favorable to study the signal of a microcanonical phase transition. We also show that the signal is very sensitive to variations in mass of the source

    DsJ(2860)D_{sJ}(2860) and DsJ(2715)D_{sJ}(2715)

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    Recently Babar Collaboration reported a new csˉc\bar{s} state DsJ(2860)D_{sJ}(2860) and Belle Collaboration observed DsJ(2715)D_{sJ}(2715). We investigate the strong decays of the excited csˉc\bar{s} states using the 3P0^{3}P_{0} model. After comparing the theoretical decay widths and decay patterns with the available experimental data, we tend to conclude: (1) DsJ(2715)D_{sJ}(2715) is probably the 1(13D1)1^{-}(1^{3}D_{1}) csˉc\bar{s} state although the 1(23S1)1^{-}(2^{3}S_{1}) assignment is not completely excluded; (2) DsJ(2860)D_{sJ}(2860) seems unlikely to be the 1(23S1)1^{-}(2^{3}S_{1}) and 1(13D1)1^{-}(1^{3}D_{1}) candidate; (3) DsJ(2860)D_{sJ}(2860) as either a 0+(23P0)0^{+}(2^{3}P_{0}) or 3(13D3)3^{-}(1^{3}D_{3}) csˉc\bar{s} state is consistent with the experimental data; (4) experimental search of DsJ(2860)D_{sJ}(2860) in the channels DsηD_s\eta, DKDK^{*}, DKD^{*}K and DsηD_{s}^{*}\eta will be crucial to distinguish the above two possibilities.Comment: 18 pages, 7 figures, 2 tables. Some discussions added. The final version to appear at EPJ

    Anisotropy in scattering of light from an atom into the guided modes of a nanofiber

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    We study the scattering of guided light from a multilevel cesium atom with the transitions between the hyperfine levels 6S1/2F=46S_{1/2}F=4 and 6P3/2F=56P_{3/2}F'=5 of the D2D_2 line into the guided modes of a nanofiber. We show that the rate of scattering of guided light from the atom in the steady-state regime into the guided modes is asymmetric with respect to the forward and backward directions and depends on the polarization of the probe field. The asymmetry between the forward and backward scattering is a result of the complex transition structure of the atom and the existence of a longitudinal component of the guided-mode profile function. In the case of a two-level atom, the rates of spontaneous emission (and consequently the rates of scattering) into the forward and backward guided modes differ from each other when the atomic dipole matrix-element vector is a complex vector in the plane that contains the fiber axis and the atomic position.Comment: 18 pages, 11 figures, accepted for publication in Phys. Rev.
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