908 research outputs found
Semi-analytic calculation of the monopole order parameter in QCD
The monopole order parameter of QCD is computed in terms of gauge invariant
field strength correlators. Both quantities are partially known from numerical
simulations on the lattice. A new insight results on the structure of the
confining vacuum.Comment: Talk presented at QCD06, Montpellier 3-7 July 2006. To appear in the
proceeding
't Hooft tensor for generic gauge group
We study monopoles in gauge theories with generic gauge group. Magnetic
charges are in one-to-one correspondence with the second homotopy classes at
spatial infinity (), which are therefore identified by the 't Hooft
tensor. We determine the 't Hooft tensor in the general case. These issues are
relevant to the understanding of Color Confinement.Comment: 5 pages. Contribution to the Conference QCD08, Montpellier 7-12 July
2008 To appear in the proceeding
Enhanced coupling design of a detuned damped structure for clic
The key feature of the improved coupling design in the Damped Detuned
Structure (DDS) is focused on the four manifolds. Rectangular geometry slots
and rectangular manifolds are used. This results in a significantly stronger
coupling to the manifolds compared to the previous design. We describe the new
design together with its wakefield damping properties.Comment: 3 pages, 8 figures, submitted to IPAC1
Dual superconducting properties of the QCD vacuum
A consistent description of the confining QCD vacuum as a dual superconductor
requires a determination of fundamental parameters such as the superconductor
correlation length and the field penetration depth , which
determine whether the superconductor is of type I or type II. We illustrate
preliminary results of a lattice determination of for the case of pure
Yang-Mills with two colors, obtained by measuring the temporal correlator of a
disorder parameter detecting dual superconductivity.Comment: 4 pages, 2 figures, talk presented at QCD05 (Montpellier) 4-9 July
200
Chiral transition and deconfinement in N_f = 2 QCD
The transition is studied by means of a disorder parameter detecting
condensation of magnetic monopoles in the vacuum. The deconfining transition is
found to coincide with the chiral transition and the susceptibility \rho,
related to the disorder parameter, is consistent with a first order phase
transition.Comment: 3 pages, 2 figures. Poster presented at Lattice2004(topology),
Fermilab, June 21-26, 200
Dual superconductivity and vacuum properties in Yang--Mills theories
We address, within the dual superconductivity model for color confinement,
the question whether the Yang-Mills vacuum behaves as a superconductor of type
I or type II. In order to do that we compare, for the theory with gauge group
SU(2), the determination of the field penetration depth with that of
the superconductor correlation length . The latter is obtained by
measuring the temporal correlator of a disorder parameter developed by the Pisa
group to detect dual superconductivity. The comparison places the vacuum close
to the border between type I and type II and marginally on the type II side. We
also check our results against the study of directly measurable effects such as
the interaction between two parallel flux tubes, obtaining consistent
indications for a weak repulsive behaviour. Future strategies to improve our
investigation are discussed.Comment: 23 pages, 15 figures. Simulations on finer lattices and with
different monopole charges added. Final version to be published in Nuclear
Physics
The interaction between center monopoles in SU(2) Yang-Mills
We study the potential between a static center monopole and antimonopole in
4d SU(2) Yang-Mills theory. Using a new numerical method, we show that the 't
Hooft loop is a dual order parameter with respect to the Wilson loop, for the
deconfinement phase transition. We observe a 3d Ising-like critical behaviour
for the dual string tension related to the spatial 't Hooft loop as a function
of the temperature.Comment: Lattice2000(Topology and Vacuum), 4 pages, 3 figure
Monopole Condensation in full QCD using the Schroedinger Functional
We use a lattice thermal partition functional to study Abelian monopole
condensation in full QCD with staggered fermions. We present
preliminary results on and lattices.Comment: Lattice2002(topology). 3 pages, 3 figure
. Design and teaching of physical education for children and youth.
The reduction of physical activity is a phenomenon that affects the world population at all ages (childhood
and adolescence, adulthood and third age) whose effects do not only concern the predisposition to risk
factors for health but also more generally well-being and good individual bio-psycho-social functioning.
Sedentary lifestyle, unfortunately, no longer affects adults and the elderly, but it is an unhealthy habit that is
grafted more and more precociously, also extending to children and adolescents. In fact, during the
developmental age we observe alarming trends of involution of motor skills with a general trend of reduction
in the quality and quantity of movements in both children and adolescents; over the last fifty years,
unfortunately, the coordination of school-age children has regressed, manifesting itself with a significant delay
in the development of coordination especially in urban populations, as well as being affected by a serious
and widespread problem of overweight and obesity in age paediatric. This paper analyses some special
educational needs of movement during childhood and adolescence, even in the presence of disabilities, and
tracks the main teaching methods that enhance the body and movement and the sensory perceptive syste
GRB 081029: Understanding Multiple Afterglow Components
We present an analysis of the unusual optical light curve of the gamma-ray
burst GRB~081029, which occurred at a redshift of z = 3.8479$. We combine X-ray
and optical observations from the Swift X-Ray Telescope and the Swift
UltraViolet/Optical Telescope with optical and infrared data obtained using the
REM and ROTSE telescopes to construct a detailed data set extending from 86 s
to approximately 100,000 s after the BAT trigger. Our data also cover a wide
energy range, from 10 keV to 0.77 eV (1.24 Angstrom to 16,000 Angstrom). The
X-ray afterglow shows a shallow initial decay followed by a rapid decay
starting at about 18,000s. The optical and infrared afterglow, however, shows
an uncharacteristic rise at about 5000 s that does not correspond to any
feature in the X-ray light curve. Our data are not consistent with synchrotron
radiation from a single-component jet interacting with an external medium. We
do, however, find that the observed light curve can be explained using
multi-component model for the jet.Comment: 4 pages, 3 figures, to appear in the AIP Conference Proceedings for
the Gamma-Ray Burst 2010 Conference, Annapolis, MD, USA, November 201
- …