10,133 research outputs found
Quark-hadron-duality in the charmonium and upsilon system
In this work we discuss the practical and conceptual issues related to
quark-hadron-duality in heavy-heavy systems. Recent measurements in the
charmonium region allow a direct test of quark-hadron-duality. We present a
formula for non-resonant background production in e^+ e^- \to D{\bar D} and
extract the resonance parameters of the \psi(3S)-\psi(6S). The obtained results
are used to investigate the upsilon energy range.Comment: 21 pages, 3 figures, references adde
Probing Topcolor-Assisted Technicolor from Top-Charm Associated Production at LHC
We propose to probe the topcolor-assisted technicolor (TC2) model from the
top-charm associated productions at the LHC, which are highly suppressed in the
Standard Model. Due to the flavor-changing couplings of the top quark with the
scalars (top-pions and top-Higgs) in TC2 model, the top-charm associated
productions can occur via both the s-channel and t-channel parton processes by
exchanging a scalar field at the LHC. We examined these processes through Monte
Carlo simulation and found that they can reach the observable level at the LHC
in quite a large part of the parameter space of the TC2 model.Comment: Version to appear in PRD (Rapid Communication
The origin of the split red clump in the Galactic bulge of the Milky Way
Near the minor axis of the Galactic bulge, at latitudes b < -5 degrees, the
red giant clump stars are split into two components along the line of sight. We
investigate this split using the three fields from the ARGOS survey that lie on
the minor axis at (l,b) = (0,-5), (0,-7.5), (0,-10) degrees. The separation is
evident for stars with [Fe/H] > -0.5 in the two higher-latitude fields, but not
in the field at b = -5 degrees. Stars with [Fe/H] < -0.5 do not show the split.
We compare the spatial distribution and kinematics of the clump stars with
predictions from an evolutionary N-body model of a bulge that grew from a disk
via bar-related instabilities. The density distribution of the peanut-shaped
model is depressed near its minor axis. This produces a bimodal distribution of
stars along the line of sight through the bulge near its minor axis, very much
as seen in our observations. The observed and modelled kinematics of the two
groups of stars are also similar. We conclude that the split red clump of the
bulge is probably a generic feature of boxy/peanut bulges that grew from disks,
and that the disk from which the bulge grew had relatively few stars with
[Fe/H] < -0.5Comment: 12 pages, 9 figures, accepted for publication in Ap
An unfolding signifier: London's Baltic Exchange in Tallinn
In the summer of 2007 an unusual cargo arrived at Muuga and Paldiski harbors outside Tallinn. It consisted of nearly 50 containers holding over 1,000 tons of building material ranging from marble columns, staircases and fireplaces, to sculpted allegorical figures, wooden paneling and old-fashioned telephone booths. They were once part of the Baltic Exchange in the City of London. Soon they will become facets of the landscape of Tallinn. The following article charts this remarkable story and deploys this fragmented monument to analyze three issues relating to the Estonian capital: the relocation of the âBronze Soldierâ, the demolition of the Sakala Culture Center, and Tallinnâs future role as European Cultural Capital in 2011
Reliability of team-based self-monitoring in critical events: A pilot study
Background: Teamwork is a critical component during critical events. Assessment is mandatory for remediation and to target training programmes for observed performance gaps. Methods: The primary purpose was to test the feasibility of team-based self-monitoring of crisis resource management with a validated teamwork assessment tool. A secondary purpose was to assess item-specific reliability and content validity in order to develop a modified context-optimised assessment tool.We conducted a prospective, single-centre study to assess team-based self-monitoring of teamwork after in-situ inter-professional simulated critical events by comparison with an assessment by observers. The Mayo High Performance Teamwork Scale (MHPTS) was used as the assessment tool with evaluation of internal consistency, item-specific consensus estimates for agreement between participating teams and observers, and content validity. Results: 105 participants and 58 observers completed the MHPTS after a total of 16 simulated critical events over 8 months. Summative internal consistency of the MHPTS calculated as Cronbachs alpha was acceptable with 0.712 for observers and 0.710 for participants. Overall consensus estimates for dichotomous data (agreement/non-agreement) was 0.62 (Cohens kappa; IQ-range 0.31-0.87). 6/16 items had excellent (kappa > 0.8) and 3/16 good reliability (kappa > 0.6). Short questions concerning easy to observe behaviours were more likely to be reliable. The MHPTS was modified using a threshold for good reliability of kappa > 0.6. The result is a 9 item self-assessment tool (TeamMonitor) with a calculated median kappa of 0.86 (IQ-range: 0.67-1.0) and good content validity.Conclusions: Team-based self-monitoring with the MHPTS to assess team performance during simulated critical events is feasible. A context-based modification of the tool is achievable with good internal consistency and content validity. Further studies are needed to investigate if team-based self-monitoring may be used as part of a programme of assessment to target training programmes for observed performance gaps. © 2013 Stocker et al.; licensee BioMed Central Ltd
Four problems regarding representable functors
Let , be two rings, an -coring and the
category of left -comodules. The category of all representable functors is shown to be equivalent to the opposite of the
category . For an -bimodule we give
necessary and sufficient conditions for the induction functor to be: a representable functor, an
equivalence of categories, a separable or a Frobenius functor. The latter
results generalize and unify the classical theorems of Morita for categories of
modules over rings and the more recent theorems obtained by Brezinski,
Caenepeel et al. for categories of comodules over corings.Comment: 16 pages, the second versio
Isospin splitting in heavy baryons and mesons
A recent general analysis of light-baryon isospin splittings is updated and
extended to charmed baryons.
The measured and splittings stand out as being difficult
to understand in terms of two-body forces alone.
We also discuss heavy-light mesons; though the framework here is necessarily
less general, we nevertheless obtain some predictions that are not strongly
model-dependent.Comment: 12 pages REVTEX 3, plus 4 uuencoded ps figures, CMU-HEP93-
An Algebraic Pairing Model with Sp(4) Symmetry and its Deformation
A fermion realization of the compact symplectic sp(4) algebra provides a
natural framework for studying isovector pairing correlations in nuclei. While
these correlations manifest themselves most clearly in the binding energies of
0^+ ground states, they also have a large effect on the energies of excited
states, including especially excited 0^+ states. In this article we consider
non-deformed as well as deformed algebraic descriptions of pairing through the
reductions of sp_{(q)}(4) to different realizations of u_{(q)}(2) for single-j
and multi-j orbitals. The model yields a classification scheme for completely
paired 0^{+} states of even-even and odd-odd nuclei in the 1d_{3/2}, 1f_{7/2},
and 1f_{5/2}2p_{1/2}2p_{3/2}1g_{9/2} shells. Phenomenological non-deformed and
deformed isospin-breaking Hamiltonians are expressed in terms of the generators
of the dynamical symmetry groups Sp(4) and Sp_{q}(4). These Hamiltonians are
related to the most general microscopic pairing problem, including isovector
pairing and isoscalar proton-neutron interaction along with non-linear
interaction in the deformed extension. In both the non-deformed and deformed
cases the eigenvalues of the Hamiltonian are fit to the relevant Coulomb
corrected experimental 0^{+} energies and this, in turn, allows us to estimate
the interaction strength parameters, to investigate isovector-pairing
properties and symmetries breaking, and to predict the corresponding energies.
While the non-deformed theory yields results that are comparable to other
theories for light nuclei, the deformed extension, which takes into account
higher-order interactions between the particles, gives a better fit to the
data. The multi-shell applications of the model provide for reasonable
predictions of energies of exotic nuclei.Comment: 19 pages, 5 figures minor changes; improvements to achieve a better
and clearer presentation of our messages and idea
Generating entangled superpositions of macroscopically distinguishable states within a parametric oscillator
We suggest a variant of the recently proposed experiment for the generation
of a new kind of Schroedinger-cat states, using two coupled parametric
down-converter nonlinear crystals [F. De Martini, Phys. Rev. Lett. 81, 2842
(1998)]. We study the parametric oscillator case and find that an entangled
Schroedinger-cat type state of two cavities, whose mirrors are placed along the
output beams of the nonlinear crystals, can be realized under suitable
conditions.Comment: RevTeX 17 pages, 9 eps files for 7 figures. Submitted to Physical
Review
W Hya : molecular inventory by ISO-SWS
Infrared spectroscopy is a powerful tool to probe the inventory of solid
state and molecular species in circumstellar ejecta. Here we analyse the
infrared spectrum of the Asymptotic Giant Branch star W Hya, obtained by the
Short and Long Wavelength Spectrometers on board of the Infrared Satellite
Observatory. These spectra show evidence for the presence of amorphous
silicates, aluminum oxide, and magnesium-iron oxide grains. We have modelled
the spectral energy distribution using laboratory measured optical properties
of these compounds and derive a total dust mass loss rate of 3E-10 Msol/yr. We
find no satisfactory fit to the 13 micron dust emission feature and the
identification of its carrier is still an open issue. We have also modelled the
molecular absorption bands due to H2O, OH, CO, CO2, SiO, and SO2 and estimated
the excitation temperatures for different bands which range from 300 to 3000K.
It is clear that different molecules giving rise to these absorption bands
originate from different gas layers. We present and analyse high resolution
Fabry-Perot spectra of the three CO2 bands in the 15 micron region. In these
data, the bands are resolved into individual Q-lines in emission, which allows
the direct determination of the excitation temperature and column density of
the emitting gas. This reveals the presence of a warm (about 450K) extended
layer of CO2, somewhere between the photosphere and the dust formation zone.
The gas in this layer is cooler than the 1000K CO2 gas responsible for the
low-resolution absorption bands at 4.25 and 15 micron. The rotational and
vibrational excitation temperatures derived from the individual Q-branch lines
of CO2 are different (450K and 150K, respectively) so that the CO2 level
population is not in LTE.Comment: To appear in Astronomy and Astrophysics A reference is adde
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