5,547 research outputs found
Scale-setting, flavour dependence and chiral symmetry restoration
We determine the flavour dependence of the renormalisation-group-invariant
running interaction through judicious use of both unquenched Dyson-Schwinger
equation and lattice results for QCD's gauge-sector two-point functions. An
important step is the introduction of a physical scale setting procedure that
enables a realistic expression of the effect of different numbers of active
quark flavours on the interaction. Using this running interaction in concert
with a well constrained class of dressed--gluon-quark vertices, we estimate the
critical number of active lighter-quarks above which dynamical chiral symmetry
breaking becomes impossible: ; and hence in whose
neighbourhood QCD is plausibly a conformal theory.Comment: 8 pages, 4 figures, 2 table
Amalgamated products and properly 3-realizable groups
In this paper, we show that the class of all properly 3-realizable groups is
closed under amalgamated free products (and HNN-extensions) over finite groups.
We recall that is said to be properly 3-realizable if there exists a
compact 2-polyhedron with and whose universal cover
has the proper homotopy type of a 3-manifold (with boundary).Comment: J. Pure Appl. Alg., to appea
Locating the Gribov horizon
We explore whether a tree-level expression for the gluon two-point function,
supposed to express effects of an horizon term introduced to eliminate the
Gribov ambiguity, is consistent with the propagator obtained in simulations of
lattice-regularised quantum chromodynamics (QCD). In doing so, we insist that
the gluon two-point function obey constraints that ensure a minimal level of
consistency with parton-like behaviour at ultraviolet momenta. In consequence,
we are led to a position which supports a conjecture that the gluon mass and
horizon scale are equivalent emergent mass-scales, each with a value of roughly
GeV; and wherefrom it appears plausible that the dynamical generation of
a running gluon mass may alone be sufficient to remove the Gribov ambiguity.Comment: 7 pages, 2 figures, 2 table
Spatial deconvolution of spectropolarimetric data: an application to quiet Sun magnetic elements
Observations of the Sun from the Earth are always limited by the presence of
the atmosphere, which strongly disturbs the images. A solution to this problem
is to place the telescopes in space satellites, which produce observations
without any (or limited) atmospheric aberrations. However, even though the
images from space are not affected by atmospheric seeing, the optical
properties of the instruments still limit the observations. In the case of
diffraction limited observations, the PSF establishes the maximum allowed
spatial resolution, defined as the distance between two nearby structures that
can be properly distinguished. In addition, the shape of the PSF induce a
dispersion of the light from different parts of the image, leading to what is
commonly termed as stray light or dispersed light. This effect produces that
light observed in a spatial location at the focal plane is a combination of the
light emitted in the object at relatively distant spatial locations. We aim to
correct the effect produced by the telescope's PSF using a deconvolution
method, and we decided to apply the code on Hinode/SP quiet Sun observations.
We analyze the validity of the deconvolution process with noisy data and we
infer the physical properties of quiet Sun magnetic elements after the
deconvolution process.Comment: 14 pages, 9 figure
Process-independent effective coupling. From QCD Green's functions to phenomenology
This article reports on a very recent proposal for a new type of
process-independent QCD effective charge [Phys.Rev.D96(2017)054026] defined, as
an anologue of the Gell-Mann-Low effective charge in QCD, on the ground of
nothing but the knowledge of the gauge-field two-point Green's function, albeit
modified within a particular computational framework; namely, the combination
of pinch technique and background field method which makes possible a
systematic rearranging of classes of diagrams in order to redefine the Green's
function and have them obey linear QED-like Slavnov-Taylor identities. We have
here calculated that effective charge, shown how strikingly well it compares to
a process-dependent effective charge based on the Bjorken sum rule; and,
finally, employed it in an exploratory calculation of the proton
electromagnetic form factor in the hard scattering regime.Comment: 13 pages, 3 figues; contribution to NStar 2017 (Columbia, USA
Multiresolution analysis (discrete wavelet transform) through Daubechies family for emotion recognition in speech
We propose a study of the mathematical properties of voice as an audio signal -- This work includes signals in which the channel conditions are not ideal for emotion recognition -- Multiresolution analysis- discrete wavelet transform – was performed through the use of Daubechies Wavelet Family (Db1-Haar, Db6, Db8, Db10) allowing the decomposition of the initial audio signal into sets of coefficients on which a set of features was extracted and analyzed statistically in order to differentiate emotional states -- ANNs proved to be a system that allows an appropriate classification of such states -- This study shows that the extracted features using wavelet decomposition are enough to analyze and extract emotional content in audio signals presenting a high accuracy rate in classification of emotional states without the need to use other kinds of classical frequency-time features -- Accordingly, this paper seeks to characterize mathematically the six basic emotions in humans: boredom, disgust, happiness, anxiety, anger and sadness, also included the neutrality, for a total of seven states to identify20th Argentinean Bioengineering Society Congress, SABI 2015 (XX Congreso Argentino de BioingenierÃa y IX Jornadas de IngenierÃa ClÃnica)28–30 October 2015, San Nicolás de los Arroyos, Argentin
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