130 research outputs found
Robust and fragile Werner states in the collective dephasing
We investigate the concurrence and Bell violation of the standard Werner
state or Werner-like states in the presence of collective dephasing. It is
shown that the standard Werner state and certain kinds of Werner-like states
are robust against the collective dephasing, and some kinds of Werner-like
states is fragile and becomes completely disentangled in a finite-time. The
threshold time of complete disentanglement of the fragile Werner-like states is
given. The influence of external driving field on the finite-time
disentanglement of the standard Werner state or Werner-like states is
discussed. Furthermore, we present a simple method to control the stationary
state entanglement and Bell violation of two qubits. Finally, we show that the
theoretical calculations of fidelity based on the initial Werner state
assumption well agree with previous experimental results.Comment: 7 pages, 6 figures, 1 table, RevTex4, Accepted by EPJ
Helicity amplitudes and electromagnetic decays of hyperon resonances
We present results for the helicity amplitudes of the lowest-lying hyperon
resonances Y*, computed within the framework of the Bonn constituent-quark
model, which is based on the Bethe-Salpeter approach. The seven parameters
entering the model were fitted to the best known baryon masses. Accordingly,
the results for the helicity amplitudes are genuine predictions. Some hyperon
resonances are seen to couple more strongly to a virtual photon with finite Q^2
than to a real photon. Other Y*'s, such as the S_{01}(1670) Lambda resonance or
the S_{11}(1620) Sigma resonance, couple very strongly to real photons. We
present a qualitative argument for predicting the behaviour of the helicity
asymmetries of baryon resonances at high Q^2.Comment: 20 pages, 26 figures, uses svjour.cls style, submitted to the
European Physical Journal
A new analysis of scattering from Roy and Steiner type equations
With the aim of generating new constraints on the OZI suppressed couplings of
chiral perturbation theory a set of six equations of the Roy and Steiner type
for the - and -waves of the scattering amplitudes is derived. The
range of validity and the multiplicity of the solutions are discussed. Precise
numerical solutions are obtained in the range E\lapprox 1 GeV which make use
as input, for the first time, of the most accurate experimental data available
at GeV for both and amplitudes.
Our main result is the determination of a narrow allowed region for the two
S-wave scattering lengths. Present experimental data below 1 GeV are found to
be in generally poor agreement with our results. A set of threshold expansion
parameters, as well as sub-threshold parameters are computed. For the latter,
matching with the SU(3) chiral expansion at NLO is performed.Comment: 45 pages, 17 figures. v2: New title, minor correction
Evidence for an Excess of Soft Photons in Hadronic Decays of Z^0
Soft photons inside hadronic jets converted in front of the DELPHI main
tracker (TPC) in events of qqbar disintegrations of the Z^0 were studied in the
kinematic range 0.2 < E_gamma < 1 GeV and transverse momentum with respect to
the closest jet direction p_T < 80 MeV/c. A clear excess of photons in the
experimental data as compared to the Monte Carlo predictions is observed. This
excess (uncorrected for the photon detection efficiency) is (1.17 +/- 0.06 +/-
0.27) x 10^{-3} gamma/jet in the specified kinematic region, while the expected
level of the inner hadronic bremsstrahlung (which is not included in the Monte
Carlo) is (0.340 +/- 0.001 +/- 0.038) x 10^{-3} gamma/jet. The ratio of the
excess to the predicted bremsstrahlung rate is then (3.4 +/- 0.2 +/- 0.8),
which is similar in strength to the anomalous soft photon signal observed in
fixed target experiments with hadronic beams.Comment: 37 pages, 9 figures, Accepted by Eur. Phys. J.
Elliptic flow of charged particles in Pb-Pb collisions at 2.76 TeV
We report the first measurement of charged particle elliptic flow in Pb-Pb
collisions at 2.76 TeV with the ALICE detector at the CERN Large Hadron
Collider. The measurement is performed in the central pseudorapidity region
(||<0.8) and transverse momentum range 0.2< < 5.0 GeV/. The
elliptic flow signal v, measured using the 4-particle correlation method,
averaged over transverse momentum and pseudorapidity is 0.087 0.002
(stat) 0.004 (syst) in the 40-50% centrality class. The differential
elliptic flow v reaches a maximum of 0.2 near = 3
GeV/. Compared to RHIC Au-Au collisions at 200 GeV, the elliptic flow
increases by about 30%. Some hydrodynamic model predictions which include
viscous corrections are in agreement with the observed increase.Comment: 10 pages, 4 captioned figures, published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/389
Measurement of the Strong Coupling alpha s from Four-Jet Observables in e+e- Annihilation
Data from e+e- annihilation into hadrons at centre-of-mass energies between
91 GeV and 209 GeV collected with the OPAL detector at LEP, are used to study
the four-jet rate as a function of the Durham algorithm resolution parameter
ycut. The four-jet rate is compared to next-to-leading order calculations that
include the resummation of large logarithms. The strong coupling measured from
the four-jet rate is alphas(Mz0)=
0.1182+-0.0003(stat.)+-0.0015(exp.)+-0.0011(had.)+-0.0012(scale)+-0.0013(mass)
in agreement with the world average. Next-to-leading order fits to the
D-parameter and thrust minor event-shape observables are also performed for the
first time. We find consistent results, but with significantly larger
theoretical uncertainties.Comment: 25 pages, 15 figures, Submitted to Euro. Phys. J.
Health promoting settings in primary health care - "hälsotorg": an implementation analysis
Background
Sweden, like many other western countries, faces increasing rates of lifestyle
related diseases and corresponding rise in costs for health care. To meet these
challenges, a number of efforts have been introduced at different societal
levels. One such effort is "Hälsotorg" (HS). HS is a new health promotion
setting that emerged in collaboration between the Swedish County Councils and
Apoteket AB, a state-owned pharmacy company. HS's overall aim was to improve
population health and facilitate inhabitants' responsibility for self-care. A
new National Public Health Policy, introduced in 2008, emphasizes more focus on
individual's needs and responsibility as well as strong need for county
councils to provide supportive environment for individual-centred health
services and increased health literacy among the population. In light of this
policy, there is a need to examine existing settings that can provide
supportive environment for individuals at community level. The aim of this
study was to explore HS's policy implementation at local level and analyse HS's
activities, in order to provide a deeper understanding of HS's potential as a
health promoting setting.
Methods
Materials included a survey and key documents related to the development and
nature of HS on local and national levels. A policy analysis inspired by Walt
and Gilson was used in data analysis. In addition, an analysis using the
principles of health promotion in relation to HS policy process and activities
was also carried out.
Results
The analysis illuminated strengths and weaknesses in the policy process, its
actors, contextual factors and activities. The health communication approach in
the analysed documents contained health promoting intentions but the health
promoting approach corresponding to a health promoting setting was neither
apparent nor shared among the stakeholders. This influenced the interpretation
and implementation of HS negatively.
Conclusions
The analysis indicates that HS has potential to be a valuable health promotion
setting for both population and individuals, given the strong intentions for a
health and empowerment building approach that is expressed in the documents.
However, for a more sustainable implementation of HS, there is need for an in-
depth understanding of the health promotion approach among HS stakeholders
Planck Intermediate Results II: Comparison of Sunyaev–Zeldovich measurements from Planck and from the Arcminute Microkelvin Imager for 11 galaxy clusters
A comparison is presented of Sunyaev–Zeldovich measurements for 11 galaxy clusters as obtained by Planck and by the ground-based interferom- eter, the Arcminute Microkelvin Imager. Assuming a universal spherically-symmetric Generalised Navarro, Frenk & White (GNFW) model for the cluster gas pressure profile, we jointly constrain the integrated Compton-Y parameter (Y500) and the scale radius (θ500) of each cluster. Our resulting constraints in the Y500 − θ500 2D parameter space derived from the two instruments overlap significantly for eight of the clusters, although, overall, there is a tendency for AMI to find the Sunyaev–Zeldovich signal to be smaller in angular size and fainter than Planck. Significant discrepancies exist for the three remaining clusters in the sample, namely A1413, A1914, and the newly-discovered Planck cluster PLCKESZ G139.59+24.18. The robustness of the analysis of both the Planck and AMI data is demonstrated through the use of detailed simulations, which also discount confusion from residual point (radio) sources and from diffuse astrophysical foregrounds as possible explanations for the discrepancies found. For a subset of our cluster sample, we have investigated the dependence of our results on the assumed pressure profile by repeating the analysis adopting the best-fitting GNFW profile shape which best matches X-ray observations. Adopting the best-fitting profile shape from the X-ray data does not, in general, resolve the discrepancies found in this subset of five clusters. Though based on a small sample, our results suggest that the adopted GNFW model may not be sufficiently flexible to describe clusters universally
Higher harmonic anisotropic flow measurements of charged particles in Pb-Pb collisions at 2.76 TeV
We report on the first measurement of the triangular , quadrangular
, and pentagonal charged particle flow in Pb-Pb collisions at 2.76
TeV measured with the ALICE detector at the CERN Large Hadron Collider. We show
that the triangular flow can be described in terms of the initial spatial
anisotropy and its fluctuations, which provides strong constraints on its
origin. In the most central events, where the elliptic flow and
have similar magnitude, a double peaked structure in the two-particle azimuthal
correlations is observed, which is often interpreted as a Mach cone response to
fast partons. We show that this structure can be naturally explained from the
measured anisotropic flow Fourier coefficients.Comment: 10 pages, 4 figures, published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/387
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