1,950 research outputs found
String Breaking in Non-Abelian Gauge Theories with Fundamental Matter Fields
We present clear numerical evidence for string breaking in three-dimensional
SU(2) gauge theory with fundamental bosonic matter through a mixing analysis
between Wilson loops and meson operators representing bound states of a static
source and a dynamical scalar. The breaking scale is calculated in the
continuum limit. In units of the lightest glueball we find . The implications of our results for QCD are discussed.Comment: 4 pages, 2 figures; equations (4)-(6) corrected, numerical results
and conclusions unchange
Scalar-gauge dynamics in (2+1) dimensions at small and large scalar couplings
We present the results of a detailed calculation of the excitation spectrum
of states with quantum numbers J^{PC}=0++, 1-- and 2++ in the three-dimensional
SU(2) Higgs model at two values of the scalar self-coupling and for fixed gauge
coupling. In the context of studies of the electroweak phase transition at
finite temperature these couplings correpond to tree-level, zero temperature
Higgs masses of 35 GeV and 120 GeV, respectively. We also study the properties
of Polyakov loop operators, which serve to test the confining properties of the
model in the symmetric phase. At both values of the scalar coupling we obtain
masses of bound states consisting entirely of gauge degrees of freedom
("W-balls"), which are very close to those obtained in the pure gauge theory.
We conclude that the previously observed, approximate decoupling of the scalar
and gauge sectors of the theory persists at large scalar couplings. We study
the crossover region at large scalar coupling and present a scenario how the
confining properties of the model in the symmetric phase are lost inside the
crossover by means of flux tube decay. We conclude that the underlying dynamics
responsible for the observed dense spectrum of states in the Higgs region at
large couplings must be different from that in the symmetric phase.Comment: 36 pages, LaTeX, 13 postscript files, to be included with epsf;
improved presentation, updated references, conclusions unchanged; version to
appear in Nucl. Phys.
Spatial string tension in lattice QCD at finite temperature
The spatial string tension across a crossover from the low temperature phase
to the high temperature phase is computed in QCD with two flavors of
non-perturbatively improved Wilson fermions at small lattice spacing a \sim
0.12fm. We find that in the low temperature phase spatial string tension agrees
well with zero temperature string tension. Furthermore, it does not show
increasing for temperatures up to T = 1.36 T_{pc}, the highest temperature
considered. Our results agree with some theoretical predictions.Comment: 8 pages, 2 figures, numerical results and both figures slightly
changed, comparison with theoretical predictions added, values of the ratio
T/T_{pc} slightly change
On the Mass Spectrum of the SU(2) Higgs Model in 2+1 Dimensions
We calculate the masses of the low-lying states with quantum numbers
in the Higgs and confinement regions of the
three-dimensional SU(2) Higgs model, which plays an important r\^ole in the
description of the thermodynamic properties of the standard model at finite
temperatures. We extract the masses from correlation functions of
gauge-invariant operators which are calculated by means of a lattice Monte
Carlo simulation. The projection properties of our lattice operators onto the
lowest states are greatly improved by the use of smearing techniques. We also
consider cross correlations between various operators with the same quantum
numbers. From these the mass eigenstates are determined by means of a
variational calculation. In the symmetric phase, we find that some of the
ground state masses are about 30\% lighter than those reported from previous
simulations. We also obtain the masses of the first few excited states in the
symmetric phase. Remarkable among these is the occurrence of a state
composed almost entirely of gauge degrees of freedom. The mass of this state,
as well as that of its first excitations, is nearly identical to the
corresponding glueball states in three-dimensional SU(2) pure gauge theory,
indicating an approximate decoupling of the pure gauge sector from the Higgs
sector of the model. We perform a detailed study of finite size effects and
extrapolate the lattice mass spectrum to the continuum.Comment: 30 pages LATEX, uses epsf.st
Developement of real time diagnostics and feedback algorithms for JET in view of the next step
Real time control of many plasma parameters will be an essential aspect in
the development of reliable high performance operation of Next Step Tokamaks.
The main prerequisites for any feedback scheme are the precise real-time
determination of the quantities to be controlled, requiring top quality and
highly reliable diagnostics, and the availability of robust control algorithms.
A new set of real time diagnostics was recently implemented on JET to prove the
feasibility of determining, with high accuracy and time resolution, the most
important plasma quantities. With regard to feedback algorithms, new
model–based controllers were developed to allow a more robust control of
several plasma parameters. Both diagnostics and algorithms were successfully
used in several experiments, ranging from H-mode plasmas to configuration with
ITBs. Since elaboration of computationally heavy measurements is often
required, significant attention was devoted to non-algorithmic methods like
Digital or Cellular Neural/Nonlinear Networks. The real time hardware and
software adopted architectures are also described with particular attention to
their relevance to ITER.Comment: 12th International Congress on Plasma Physics, 25-29 October 2004,
Nice (France
Qualitative characteristics of four Sicilian monofloral honeys from Apis mellifera ssp. sicula
Four monofloral honeys, obtained from the Sicilian black bee by foraging on thistle, sulla, chestnut and eucalyp-tus, were studied. Results showed that the phenolic composition of chestnut honey was the highest (316 mg gallic acid equivalent GAE/kg), while that of sulla honey was the lowest (122 mg GAE/kg). Data confirmed a correla-tion between the total phenol content and colour intensity in chestnut honey, which was the darkest of the four samples. Sulla honey showed the highest antioxidant activity, while eucalyptus honey had the highest mineral content (K, Ca, Mg, and Na). Thistle honey showed the most intense floral and fruity aromas, as well as an intense yellow colour. Principal component analysis showed the potential to discriminate different honeys in three different quadrants
Breeding strategy shapes the composition of bacterial communities in female Nile tilapia reared in a recirculating aquaculture system
publishedVersio
Medical workforce planning in a changing health context: Comparison between Italy and Europe
An increasing need for healthcare workers as been estimated worldwide. To provide a comprehensive framework of the medical workforce in Italy, we investigated the post-lauream medical workforce training supply and demand. Further, a comparison of the medical workforce between Italy and other European Countries with a similar epidemiological and/or demographic context was performed. The distribution of pre-and post-lauream medical educational providers and post-lauream resources in place in Italy was analyzed among Italian macro-areas in the academic years 2015-2016, 2016-2017 and 2017-2018.Italy and the European countries in study were compared in term of post-lauream funding and number of active physicians by specialization per 1,000 inhabitants. Open access data from official Italian and European institutional sources were used. The most of medical schools were distributed in the North, followed by South, islands and Central Italy, while the highest enrolment rate in the pre-lauream medical education was reported in Central Italy, followed by South & islands and North. The total number of active residency programs increased from 1092 to 1286 in the three considered academic years, while number of post-lauream training contracts decreased from 11.0 to 10.2 per 100,000 inhabitants. A misalignment between contracts assigned to residency programs and grants assigned to general practitioners specific courses was observed. Furthermore, when compared to the EU countries in study, Italy documented the lowest number of post-graduated training positions in 2015, with a rate of 12.1/100,000 inhabitants. Also, an excess of medical specialists (3.06 per 1,000 inhabitants) with a simultaneous shortage of general practitioners (0.89 per 1,000 inhabitants) was reported. On the contrary, Italy documented the highest number of paediatric practitioners. More efforts, including the implementation of adequate tools, are required both at national and regional level in order to provide a medical workforce planning in line with a continuously changing health context
Radiating and non-radiating sources in elasticity
In this work, we study the inverse source problem of a fixed frequency for
the Navier's equation. We investigate that nonradiating external forces. If the
support of such a force has a convex or non-convex corner or edge on their
boundary, the force must be vanishing there. The vanishing property at corners
and edges holds also for sufficiently smooth transmission eigenfunctions in
elasticity. The idea originates from the enclosure method: The energy identity
and new type exponential solutions for the Navier's equation.Comment: 17 page
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