6,615 research outputs found
Schwinger-Dyson equations and the quark-antiquark static potential
In lattice QCD, a confining potential for a static quark-antiquark pair can
be computed with the Wilson loop technique. This potential, dominated by a
linear potential at moderate distances, is consistent with the confinement with
a flux tube, an extended and scalar system also directly observable in lattice
QCD. Quantized flux tubes have also been observed in another class of
confinement, the magnetic confinement in type II superconductors. On the other
hand the solution of Schwinger Dyson Equations, say with the Landau gauge
fixing and the truncation of the series of Feynman diagrams, already at the
rainbow level for the self energy and at the ladder level for the Bethe
Salpeter equation, provides a signal of a possible inverse quartic potential in
momentum space derived from one gluon and one ghost exchange, consistent with
confinement. Here we address the successes, difficulties and open problems of
the matching of these two different perspectives of confinement, the
Schwinger-Dyson perspective versus the flux tube perspective.Comment: 12 pages, 18 figures; talk presented at QCD-TNT, Trento, 7-11 sep
200
First study of the gluon-quark-antiquark static potential in SU(3) Lattice QCD
We study the long distance interaction for hybrid hadrons, with a static
gluon, a quark and an antiquark with lattice QCD techniques. A Wilson loop
adequate to the static hybrid three-body system is developed and, using a 24^3
x 48 periodic lattice with beta=6.2 and a ~ 0.075 fm, two different geometries
for the gluon-quark segment and the gluon-antiquark segment are investigated.
When these segments are perpendicular, the static potential is compatible with
confinement realized with a pair of fundamental strings, one linking the gluon
to the quark and another linking the same gluon to the antiquark. When the
segments are parallel and superposed, the total string tension is larger and
agrees with the Casimir Scaling measured by Bali. This can be interpreted with
a type-II superconductor analogy for the confinement in QCD, with repulsion of
the fundamental strings and with the string tension of the first topological
excitation of the string (the adjoint string) larger than the double of the
fundamental string tension.Comment: 4 pages RevTeX, 4 figure
Partition functions and elliptic genera from supergravity
We develop the spacetime aspects of the computation of partition functions
for string/M-theory on AdS(3) xM. Subleading corrections to the semi-classical
result are included systematically, laying the groundwork for comparison with
CFT partition functions via the AdS(3)/CFT(2) correspondence. This leads to a
better understanding of the "Farey tail" expansion of Dijkgraaf et. al. from
the point of view of bulk physics. Besides clarifying various issues, we also
extend the analysis to the N=2 setting with higher derivative effects included.Comment: 34 page
Recommendations for triage, prioritization and treatment of breast cancer patients during the COVID-19 pandemic
The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) associated disease (COVID-19) outbreak seriously challenges globally all health care systems and professionals. Expert projections estimate that despite social distancing and lockdown being practiced, we have yet to feel the full impact of COVID-19. In this manuscript we provide guidance to prepare for the impact of COVID-19 pandemic on breast cancer patients and advise on how to triage, prioritize and organize diagnostic procedures, surgical, radiation and medical treatments
Teleportation of entangled states without Bell-state measurement
In a recent paper [Phys. Rev. A 70, 025803 (2004)] we presented a scheme to
teleport an entanglement of zero- and one-photon states from a bimodal cavity
to another one, with 100% success probability. Here, inspired on recent results
in the literature, we have modified our previous proposal to teleport the same
entangled state without using Bell-state measurements. For comparison, the time
spent, the fidelity, and the success probability for this teleportation are
considered.Comment: 4 pages, 1 figure, published in Phys. Rev. A 72, 045802 (2005
Accuracy of a teleported trapped field state inside a single bimodal cavity
We propose a simplified scheme to teleport a superposition of coherent states
from one mode to another of the same bimodal lossy cavity. Based on current
experimental capabilities, we present a calculation of the fidelity that can be
achieved, demonstrating accurate teleportation if the mean photon number of
each mode is at most 1.5. Our scheme applies as well for teleportation of
coherent states from one mode of a cavity to another mode of a second cavity,
both cavities embedded in a common reservoir.Comment: 4 pages, 2 figures, in appreciation for publication in Physical
Review
Elastic turbulence in shear banding wormlike micelles
We study the dynamics of the Taylor-Couette flow of shear banding wormlike
micelles. We focus on the high shear rate branch of the flow curve and show
that for sufficiently high Weissenberg numbers, this branch becomes unstable.
This instability is strongly sub-critical and is associated with a shear stress
jump. We find that this increase of the flow resistance is related to the
nucleation of turbulence. The flow pattern shows similarities with the elastic
turbulence, so far only observed for polymer solutions. The unstable character
of this branch led us to propose a scenario that could account for the recent
observations of Taylor-like vortices during the shear banding flow of wormlike
micelles
Curved BPS domain walls and RG flow in five dimensions
We determine, in the context of five-dimensional gauged
supergravity with vector and hypermultiplets, the conditions under which curved
(non Ricci flat) supersymmetric domain wall solutions may exist. These curved
BPS domain wall solutions may, in general, be supported by non-constant vector
and hyper scalar fields. We establish our results by a careful analysis of the
BPS equations as well as of the associated integrability conditions and the
equations of motion. We construct an example of a curved BPS solution in a
gauged supergravity model with one hypermultiplet. We also discuss the dual
description of curved BPS domain walls in terms of RG flows.Comment: 18 pages, LaTeX, 5 figures; added reference
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