52,528 research outputs found
A proposal for a generalized canonical osp(1,2) quantization of dynamical systems with constraints
The aim of this paper is to consider a possibility of constructing for
arbitrary dynamical systems with first-class constraints a generalized
canonical quantization method based on the osp(1,2) supersymmetry principle.
This proposal can be considered as a counterpart to the osp(1,2)-covariant
Lagrangian quantization method introduced recently by Geyer, Lavrov and
M\"ulsch. The gauge dependence of Green's functions is studied. It is shown
that if the parameter m^2 of the osp(1,2) superalgebra is not equal to zero
then the vacuum functional and S-matrix depend on the gauge. In the limit the gauge independence of vacuum functional and S - matrix are restored. The
Ward identities related to the osp(1,2) symmetry are derived.Comment: Revised version. To appear in Mod.Phys.Lett.
S-DIMM+ height characterization of day-time seeing using solar granulation
To evaluate site quality and to develop multi-conjugative adaptive optics
systems for future large solar telescopes, characterization of contributions to
seeing from heights up to at least 12 km above the telescope is needed. We
describe a method for evaluating contributions to seeing from different layers
along the line-of-sight to the Sun. The method is based on Shack Hartmann
wavefront sensor data recorded over a large field-of-view with solar
granulation and uses only measurements of differential image displacements from
individual exposures, such that the measurements are not degraded by residual
tip-tilt errors. We conclude that the proposed method allows good measurements
when Fried's parameter r_0 is larger than about 7.5 cm for the ground layer and
that these measurements should provide valuable information for site selection
and multi-conjugate development for the future European Solar Telescope. A
major limitation is the large field of view presently used for wavefront
sensing, leading to uncomfortably large uncertainties in r_0 at 30 km distance.Comment: Accepted by AA 22/01/2010 (12 pages, 11 figures
Photometric Solutions for Detached Eclipsing Binaries: selection of ideal distance indicators in the SMC
Detached eclipsing binary stars provide a robust one-step distance
determination to nearby galaxies. As a by-product of Galactic microlensing
searches, catalogs of thousands of variable stars including eclipsing binaries
have been produced by the OGLE, MACHO and EROS collaborations. We present
photometric solutions for detached eclipsing binaries in the Small Magellanic
Cloud (SMC) discovered by the OGLE collaboration. The solutions were obtained
with an automated version of the Wilson-Devinney program. By fitting mock
catalogs of eclipsing binaries we find that the normalized stellar radii
(particularly their sum) and the surface brightness ratio are accurately
described by the fitted parameters and estimated standard errors, despite
various systematic uncertainties. In many cases these parameters are well
constrained. In addition we find that systems exhibiting complete eclipses can
be reliably identified where the fractional standard errors in the radii are
small. We present two quantitatively selected sub-samples of eclipsing binaries
that will be excellent distance indicators. These can be used both for
computation of the distance to the SMC and to probe its structure. One
particularly interesting binary has a very well determined solution, exhibits
complete eclipses, and is comprised of well detached G-type, class giants.Comment: 29 pages, 12 figures. To be published in Ap
Heavy Quark Expansion and Preasymptotic Corrections to Decay Widths in the 't Hooft Model
We address nonperturbative power corrections to inclusive decay widths of
heavy flavor hadrons in the context of the 't Hooft model (two-dimensional QCD
at N_c->oo), with the emphasis on the spectator-dependent effects sensitive to
the flavor of the spectator. The summation of exclusive widths is performed
analytically using the `t Hooft equation. We show that the 1/m_Q expansion of
both the Weak Annihilation and Pauli Interference widths coincides with the OPE
predictions, to the computed orders. Violation of local duality in the
inclusive widths is quantified, and the new example is identified where the OPE
prediction and the actual effect are completely saturated by a single final
state. The qualitative aspects of quark hadronization emerging from the
analysis in the 't Hooft model are discussed. Certain aspects of summation of
spectator-independent hadronic weak decay widths are given in more detail,
which were not spelled out previously. We also give some useful details of the
1/m_Q expansion in the 't~Hooft model.Comment: 54 pages, 8 figures in the text. Version to be published in Phys.
Rev. D. A number of typos are corrected and relevant references added.
Clarifications in Conclusions, Appendices 2.1 and 3 are adde
Quantum state preparation and control of single molecular ions
Preparing molecules at rest and in a highly pure quantum state is a long
standing dream in chemistry and physics, so far achieved only for a select set
of molecules in dedicated experimental setups. Here, a quantum-limited
combination of mass spectrometry and Raman spectroscopy is proposed that should
be applicable to a wide range of molecular ions. Excitation of electrons in the
molecule followed by uncontrolled decay and branching into several lower energy
states is avoided. Instead, the molecule is always connected to rotational
states within the electronic and vibrational ground-state manifold, while a
co-trapped atomic ion provides efficient entropy removal and allows for
extraction of information on the molecule. The outlined techniques might enable
preparation, manipulation and measurement of a large multitude of molecular ion
species with the same instrument, with applications including, but not limited
to, precise determination of molecular properties and fundamental tests of
physics.Comment: 12 pages, 2 figures, reformatted for resubmissio
Scattering of coherent states on a single artificial atom
In this work we theoretically analyze a circuit QED design where propagating
quantum microwaves interact with a single artificial atom, a single Cooper pair
box. In particular, we derive a master equation in the so-called transmon
regime, including coherent drives. Inspired by recent experiments, we then
apply the master equation to describe the dynamics in both a two-level and a
three-level approximation of the atom. In the two-level case, we also discuss
how to measure photon antibunching in the reflected field and how it is
affected by finite temperature and finite detection bandwidth.Comment: 18 pages, 7 figure
Microscopic analytical theory of a correlated, two-dimensional N-electron gas in a magnetic field
We present a microscopic, analytical theory describing a confined N-electron
gas in two dimensions subject to an external magnetic field. The number of
electrons N and strength of the electron-electron interaction can be
arbitrarily large, and all Landau levels are included implicitly. A possible
connection with the Integer and Fractional Quantum Hall Effects is proposed.Comment: The revised version contains minor changes to text. To be published
in J. Phys: Condens. Mat
Algebro-Geometric Solutions of the Boussinesq Hierarchy
We continue a recently developed systematic approach to the Bousinesq (Bsq)
hierarchy and its algebro-geometric solutions. Our formalism includes a
recursive construction of Lax pairs and establishes associated
Burchnall-Chaundy curves, Baker-Akhiezer functions and Dubrovin-type equations
for analogs of Dirichlet and Neumann divisors. The principal aim of this paper
is a detailed theta function representation of all algebro-geometric
quasi-periodic solutions and related quantities of the Bsq hierarchy.Comment: LaTeX, 48 page
Factorization fits to charmless strangeless B decays
We present fits to charmless strangeless hadronic B decay data for mean
branching ratios and CP-violating asymmetries using the QCD factorization model
of Beneke et al. Apart from one CP-violating parameter, the model gives a very
good representation of 26 measured data. We find the CKM angle alpha = (93.5
+/- 8.4 -1.3) degrees and to be quite stable to plausible "charming penguin"
corrections.Comment: 4 pages, LaTeX, Minor changes to text, references adde
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