10,969 research outputs found
The Bargmann representation for the quantum mechanics on a sphere
The Bargmann representation is constructed corresponding to the coherent
states for a particle on a sphere introduced in: K. Kowalski and J.
Rembielinski, J. Phys. A: Math. Gen. 33, 6035 (2000). The connection is
discussed between the introduced formalism and the standard approach based on
the Hilbert space of square integrable functions on a sphere S^2.Comment: LaTe
Coherent states for the q-deformed quantum mechanics on a circle
The q-deformed coherent states for a quantum particle on a circle are
introduced and their properties investigated.Comment: 11 pages, 2 PostScript figure
On the uncertainty relations and squeezed states for the quantum mechanics on a circle
The uncertainty relations for the position and momentum of a quantum particle
on a circle are identified minimized by the corresponding coherent states. The
sqeezed states in the case of the circular motion are introduced and discussed
in the context of the uncertainty relations.Comment: 4 figure
Causal sets and conservation laws in tests of Lorentz symmetry
Many of the most important astrophysical tests of Lorentz symmetry also
assume that energy-momentum of the observed particles is exactly conserved. In
the causal set approach to quantum gravity a particular kind of Lorentz
symmetry holds but energy-momentum conservation may be violated. We show that
incorrectly assuming exact conservation can give rise to a spurious signal of
Lorentz symmetry violation for a causal set. However, the size of this spurious
signal is much smaller than can be currently detected and hence astrophysical
Lorentz symmetry tests as currently performed are safe from causal set induced
violations of energy-momentum conservation.Comment: 8 pages, matches version published in PR
Coherent states for a particle on a sphere
The coherent states for a particle on a sphere are introduced. These states
are labelled by points of the classical phase space, that is the position on
the sphere and the angular momentum of a particle. As with the coherent states
for a particle on a circle discussed in Kowalski K {\em et al} 1996 {\em J.
Phys. A} {\bf 29} 4149, we deal with a deformation of the classical phase space
related with quantum fluctuations. The expectation values of the position and
the angular momentum in the coherent states are regarded as the best possible
approximation of the classical phase space. The correctness of the introduced
coherent states is illustrated by an example of the rotator.Comment: LaTeX, 16 pages, 2 figure
Blackbody radiation in \kappa-Minkowski spacetime
We have computed the black body radiation spectra in Minkowski
space-time, using the quantum mechanical picture of massless scalar particles
as well as effective quantum field theory picture. The black body radiation
depends on how the field theory (and thus how the Poincar\'e algebra)
handles the ordering effect of the noncommutative space-time. In addition,
there exists a natural momentum cut-off of the order , beyond which a
new real mode takes its shape from a complex mode and the old real mode flows
out to be a new complex mode. However, the new high momentum real mode should
not be physical since its contributions to the black-body radiation spoils the
commutative limit.Comment: 22pages, No figure, some corrections, to appear in Phys. Rev.
Exclusive diffractive processes at HERA within the dipole picture
We present a simultaneous analysis, within an impact parameter dependent
saturated dipole model, of exclusive diffractive vector meson (J/psi, phi and
rho) production, deeply virtual Compton scattering and the total gamma* p cross
section data measured at HERA. Various cross sections measured as a function of
the kinematic variables Q^2, W and t are well described, with little
sensitivity to the details of the vector meson wave functions. We determine the
properties of the gluon density in the proton in both longitudinal and
transverse dimensions, including the impact parameter dependent saturation
scale. The overall success of the description indicates universality of the
emerging gluon distribution and proton shape.Comment: 48 pages, 28 figures, the final version to appear in Physical Review
Discussion: Clinical measurements of periodontitis
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72157/1/j.1600-051X.1986.tb01490.x.pd
The School Superintendent: Roles, Challenges, and Issues
The purposes of this chapter are to detail the development of the office of school superintendent, to examine issues of gender and race, to identify contemporary issues affecting practice, and to identify future research topics. The first two sections provide historical perspectives summarizing how the position has evolved over the past 150 years at three different levels-state, intermediate district, and local district. A discussion of the position\u27s history produces five role conceptualizations; having evolved over the past 150 years, these characterizations provide a mosaic of contemporary expectations. Next, considerable attention is given to the causes and implications of race and gender underrepresentation, and research on this topic is summarized. Contemporary challenges to practice are then presented in relation to education finance, school reform, social contexts of schooling, and school board relationships. Last, suggestions for conducting research on the normative and actual roles, underrepresentation, and contemporary challenges are provided
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