237,066 research outputs found
Analytical methods in heavy quark physics and the case of
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
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
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
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
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 . 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 and also on the curvature
, and imply, modulo a very natural assumption, the
inequality , and therefore the absolute bound
.Comment: 64 pages, Late
Designing Redress: A Study About Grievances Against Public Bodies
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
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
and
Recently Babar Collaboration reported a new state
and Belle Collaboration observed . We investigate the strong
decays of the excited states using the model. After
comparing the theoretical decay widths and decay patterns with the available
experimental data, we tend to conclude: (1) is probably the
state although the
assignment is not completely excluded; (2) seems unlikely to be
the and candidate; (3)
as either a or state is
consistent with the experimental data; (4) experimental search of
in the channels , , and
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
We study the scattering of guided light from a multilevel cesium atom with
the transitions between the hyperfine levels and
of the 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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