20,698 research outputs found
Built-in bleeder system in laminated plastic structures
Method is described for interplying resin absorbing, glass bleeder cloth with the layup for fabricating laminated nonflammable plastic structures with wrinkle-free surfaces
Universality in the Electroproduction of Vector Mesons
We study universality in the electroproduction of vector mesons using a
unified nonperturbative approach which has already proved to reproduce
extremely well the available experimental data. In this framework, after the
extraction of factors that are specific of each vector meson, we arrive at a
reduced integrated elastic cross section which is universal. Our calculations
suggest a finite infrared behavior for the strong coupling constant.Comment: 22 pages, 10 figure
Gluon and ghost propagators in the Landau gauge: Deriving lattice results from Schwinger-Dyson equations
We show that the application of a novel gauge invariant truncation scheme to
the Schwinger-Dyson equations of QCD leads, in the Landau gauge, to an infrared
finite gluon propagator and a divergent ghost propagator, in qualitative
agreement with recent lattice data.Comment: 9 pages, 2 figures; v3: typos corrected; v2: discussion on numerical
results expanded, considerations about the Kugo-Ojima confinement criterion
adde
Recommended from our members
Damages caused by cotton rat, Sigmodon hispidus zanjonensis, on sugar cane in San Pedrosula, Honduras
Technical assistance was given to CompañĂa Azucarera Hondureña, S.A. (Agro-Industrial Co.), Honduras, Central America, to determine if a campaign against noxious rodents to agriculture crops was needed. Several trappings were carried out at different places using snap traps to determine the population structure of rodents associated with the crop, and live traps to determine the index or density of the Sigmodon hispidus rat population, which was identified as being responsible for the damage to sugarcane. Results were 43.24% adult males, 14.86% young males, 31.41% adult females, and 10.47% young females. Of the adult females captured, 54.83% were pregnant with an average of 3 to 4 embryos per rat. A control demonstration combat was carried out at one of the experimental stations with a bait prepared with 2% zinc phosphide in a place where it had been previously determined there was a population of 39 rats per hectare. After such control, the population was reduced to 18 rats per hectare, which represents an efficiency of 53.85%. An evaluation of damages was also measured at different places to determine the degree of loss caused by the rats, which proved to be 22.79% damage. The size of the sample was estimated in 3 samples per hectare, with a level of confidence of 95%
Recent studies of top quark properties and decays at hadron colliders
The top quark is the heaviest known elementary particle. Observed for the
first time in 1995 at the Tevatron by the CDF and D0 experiments, it has become
object of several studies aimed at fully characterize its properties and
decays. Precise determinations of top quark characteristics verify the internal
consistency of the standard model and are sensitive to new physics phenomena.
With the advent of the large top quark production rates generated at the LHC,
top quark studies have reached unprecedented statistical precision. This review
summarizes the recent measurements of top quark properties and studies of its
decays performed at the LHC and Tevatron.Comment: 13 pages, 4 figures, 5 tables, Presented at Flavor Physics and CP
Violation (FPCP 2012), Hefei, China, May 21-25, 201
Smoothed Particle Hydrodynamics simulations of the core-degenerate scenario for Type Ia supernovae
The core-degenerate (CD) scenario for type Ia supernovae (SN Ia) involves the
merger of the hot core of an asymptotic giant branch (AGB) star and a white
dwarf, and might contribute a non-negligible fraction of all thermonuclear
supernovae. Despite its potential interest, very few studies, and based on only
crude simplifications, have been devoted to investigate this possible scenario,
compared with the large efforts invested to study some other scenarios. Here we
perform the first three-dimensional simulations of the merger phase, and find
that this process can lead to the formation of a massive white dwarf, as
required by this scenario. We consider two situations, according to the mass of
the circumbinary disk formed around the system during the final stages of the
common envelope phase. If the disk is massive enough, the stars merge on a
highly eccentric orbit. Otherwise, the merger occurs after the circumbinary
disk has been ejected and gravitational wave radiation has brought the stars
close to the Roche lobe radius on a nearly circular orbit. Not surprisingly,
the overall characteristics of the merger remnants are similar to those found
for the double-degenerate (DD) scenario, independently of the very different
core temperature and of the orbits of the merging stars. They consist of a
central massive white dwarf, surrounded by a hot, rapidly rotating corona and a
thick debris region.Comment: 17 pages, 10 figures. Accepted for publication in MNRA
Magnus Expansion and Three-Neutrino Oscillations in Matter
We present a semi-analytical derivation of the survival probability of solar
neutrinos in the three generation scheme, based on the Magnus approximation of
the evolution operator of a three level system, and assuming a mass hierarchy
among neutrino mass eigenstates. We have used an exponential profile for the
solar electron density in our approximation. The different interesting density
regions that appear throughout the propagation are analyzed. Finally, some
comments on the allowed regions in the solar neutrino parameter space are
addressed.Comment: RevTex4 style, 5 pages including 5 figures. Presented at Mexican
School of Astrophysics 2002, Guanajuato, Mexico, 31 Jul - 7 Aug 2002. Final
version to appear in the Proceedings of IX Mexican Workshop on Particles and
Fields Physics Beyond the Standard Model, Colima Col. Mexico, November 17-22,
200
A clean signal for a top-like isosinglet fermion at the Large Hadron Collider
We predict a clean signal at the Large Hadron Collider (=14 TeV for
a scenario where there is a top-like, charge +2/3 vectorlike isosinglet
fermion. Such a quark, via mixing with the standard model top, can undergo
decays via both flavour-changing Z-boson coupling and flavour-changing Yukawa
interactions. We concentrate on the latter channel, and study the situation
where, following its pair-production, the heavy quark pair gives rise to two
tops and two Higgs boson. We show that the case where each Higgs decays in the
channel, there can be a rather distinct and background-free signal
that can unveil the existence of the vectorlike isosinglet quark of this kind.Comment: 14 pages, 5 figures, 4 table
Complex Scaled Spectrum Completeness for Coupled Channels
The Complex Scaling Method (CSM) provides scattering wave functions which
regularize resonances and suggest a resolution of the identity in terms of such
resonances, completed by the bound states and a smoothed continuum. But, in the
case of inelastic scattering with many channels, the existence of such a
resolution under complex scaling is still debated. Taking advantage of results
obtained earlier for the two channel case, this paper proposes a representation
in which the convergence of a resolution of the identity can be more easily
tested. The representation is valid for any finite number of coupled channels
for inelastic scattering without rearrangement.Comment: Latex file, 13 pages, 4 eps-figure
- …