356 research outputs found
On multidimensional poverty rankings of binary attributes
We address the problem of ranking distributions of attributes in terms of poverty, when the attributes are represented by binary variables. To accomplish this task, we identify a suitable notion of “multidimensional poverty line” and characterize axiomatically the Head-Count and the Attribute-Gap poverty rankings, which are the natural counterparts of the most widely used income poverty indices. Finally, we apply our methodology and compare our empirical results with those obtained with some other well-known poverty measures
On the Rational Terms of the one-loop amplitudes
The various sources of Rational Terms contributing to the one-loop amplitudes
are critically discussed. We show that the terms originating from the generic
(n-4)-dimensional structure of the numerator of the one-loop amplitude can be
derived by using appropriate Feynman rules within a tree-like computation. For
the terms that originate from the reduction of the 4-dimensional part of the
numerator, we present two different strategies and explicit algorithms to
compute them.Comment: 14 pages, 3 figures, uses axodraw.st
CutTools: a program implementing the OPP reduction method to compute one-loop amplitudes
We present a program that implements the OPP reduction method to extract the
coefficients of the one-loop scalar integrals from a user defined
(sub)-amplitude or Feynman Diagram, as well as the rational terms coming from
the 4-dimensional part of the numerator. The rational pieces coming from the
epsilon-dimensional part of the numerator are treated as an external input, and
can be computed with the help of dedicated tree-level like Feynman rules.
Possible numerical instabilities are dealt with the help of arbitrary
precision routines, that activate only when needed.Comment: Version published in JHE
Automated computation of one-loop integrals in massless theories
We consider one-loop tensor and scalar integrals, which occur in a massless
quantum field theory and we report on the implementation into a numerical
program of an algorithm for the automated computation of these one-loop
integrals. The number of external legs of the loop integrals is not restricted.
All calculations are done within dimensional regularization.Comment: 28 pages, version to be publishe
Optimizing the Reduction of One-Loop Amplitudes
We present an optimization of the reduction algorithm of one-loop amplitudes
in terms of master integrals. It is based on the exploitation of the polynomial
structure of the integrand when evaluated at values of the loop-momentum
fulfilling multiple cut-conditions, as emerged in the OPP-method. The
reconstruction of the polynomials, needed for the complete reduction, is rended
very versatile by using a projection-technique based on the Discrete Fourier
Transform. The novel implementation is applied in the context of the NLO QCD
corrections to u d-bar --> W+ W- W+
Monte Carlo studies of the jet activity in Higgs + 2 jet events
Tree-level studies have shown in the past that kinematical correlations
between the two jets in Higgs+2-jet events are direct probes of the Higgs
couplings, e.g. of their CP nature. In this paper we explore the impact of
higher-order corrections on the azimuthal angle correlation of the two leading
jets and on the rapidity distribution of extra jets. Our study includes
matrix-element and shower MC effects, for the two leading sources of Higgs plus
two jet events at the CERN LHC, namely vector-boson and gluon fusion. We show
that the discriminating features present in the previous leading-order matrix
element studies survive.Comment: 12 pages, 10 figures. Version to appear on JHEP. Figs. 5-8 replaced
with colour version
Comparative phenotypic and functional analyses of the effects of autologous plasma and recombinant human macrophage-colony stimulating factor (M-CSF) on porcine monocyte to macrophage differentiation
Abstract Porcine monocyte-derived macrophages (moMΦ) have been employed as a model cell in numerous studies of the porcine immune system. However, the lack of a standardized method for moMΦ differentiation hampers the comparison of results coming from the use of different laboratory protocols. In this study we compared the use of varying concentrations of autologous plasma (10, 20 and 30% v/v) or recombinant human macrophage-colony stimulating factor (hM-CSF; 50, 100, and 200 ng/ml) to differentiate porcine monocytes into macrophages. Changes in cell morphology and surface marker expression were assessed by confocal microscopy and flow cytometry. Macrophage differentiation was evaluated by analysing TNF-α response to LPS stimulation and determining cytokine secretion patterns under both basal conditions and after classical and alternative activation. The effects of the differentiation methods on metabolic activity and susceptibility to infection with the myelotropic African swine fever virus (ASFV) were also evaluated. Monocytes cultured using the different culture conditions tested augmented in dimension and cellular complexity, but increasing porcine plasma concentrations resulted in a dose dependent enhancement in granularity and a marked pleomorphism. As expected, CD163, MHC class II DR and CD203a expression were up-regulated in both hM-CSF (M-CSF-moMΦ) and autologous plasma cultured macrophages (AP-moMΦ), although a lower percentage of CD163+ cells were found following differentiation with high percentages of porcine plasma. We observed enhanced number of viable cells using high concentration of hM-CSF compared to porcine plasma, suggesting a proliferative effect. Irrespective of differentiation conditions, monocyte differentiation into macrophages resulted in an increased susceptibility to ASFV and yielded larger amounts of LPS-induced TNF-α. AP-moMΦ showed a higher basal release of IL-1RA compared to those cultured with hM-CSF and displayed a reduced ability to respond to classical activation, suggesting that the use of high percentages of porcine plasma led to the acquisition of a M2-like phenotype. We conclude that all the protocols tested in this study can be considered as suitable to produce porcine moMΦ, although the use of hM-CSF provides high responsiveness to M1 polarization. Since a higher phenotypic and functional inter-animal variability was observed in AP-moMΦ, we propose that the use of low concentration of hM-CSF should be adopted as the method of choice to provide a better reproducibility between experiments
Heavy neutrino signals at large hadron colliders
We study the LHC discovery potential for heavy Majorana neutrino singlets in
the process pp -> W+ -> l+ N -> l+ l+ jj (l=e,mu) plus its charge conjugate.
With a fast detector simulation we show that backgrounds involving two
like-sign charged leptons are not negligible and, moreover, they cannot be
eliminated with simple sequential kinematical cuts. Using a likelihood analysis
it is shown that, for heavy neutrinos coupling only to the muon, LHC has 5
sigma sensitivity for masses up to 200 GeV in the final state mu+- mu+- jj.
This reduction in sensitivity, compared to previous parton-level estimates, is
driven by the ~ 10^2-10^3 times larger background. Limits are also provided for
e+- e+- jj and e+- mu+- jj final states, as well as for Tevatron. For heavy
Dirac neutrinos the prospects are worse because backgrounds involving two
opposite charge leptons are much larger. For this case, we study the
observability of the lepton flavour violating signal e+- mu-+ jj. As a
by-product of our analysis, heavy neutrino production has been implemented
within the ALPGEN framework.Comment: Latex 36 pages, 49 PS figures. Major extension incorporating analysis
for e+- e+-, e+- mu+- and e+- mu-+ final states. Final version to appear in
JHE
Automation of one-loop QCD corrections
We present the complete automation of the computation of one-loop QCD
corrections, including UV renormalization, to an arbitrary scattering process
in the Standard Model. This is achieved by embedding the OPP integrand
reduction technique, as implemented in CutTools, into the MadGraph framework.
By interfacing the tool so constructed, which we dub MadLoop, with MadFKS, the
fully automatic computation of any infrared-safe observable at the
next-to-leading order in QCD is attained. We demonstrate the flexibility and
the reach of our method by calculating the production rates for a variety of
processes at the 7 TeV LHC.Comment: 64 pages, 12 figures. Corrected the value of m_Z in table 1. In table
2, corrected the values of cross sections in a.4 and a.5 (previously computed
with mu=mtop/2 rather than mu=mtop/4). In table 2, corrected the values of
NLO cross sections in b.3, b.6, c.3, and e.7 (the symmetry factor for a few
virtual channels was incorrect). In sect. A.4.3, the labeling of the
four-momenta was incorrec
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