1,959 research outputs found
PROSPINO: A Program for the Production of Supersymmetric Particles in Next-to-leading Order QCD
A Fortran-program for the production cross-sections of squarks and gluinos at
hadron colliders is described. It includes full next-to-leading order SUSY-QCD
corrections to all possible final states (\squark\squarkbar, \gluino\gluino,
\squark\gluino, \squark\squark). The program allows to calculate total
cross-sections as well as differential distributions in the transverse momentum
p_t and the rapidity y of one of the outgoing particles. In addition cuts in
p_t and y can easily be implemented.Comment: 12 pages, latex, no figures, Complete postscript file and FORTRAN
source codes available from http://wwwcn.cern.ch/~mspira/prospino
A Note on W Production at HERA
We discuss W boson production at HERA including NLO QCD corrections.Comment: 2 pages, latex, 2 figures, Contribution to the 3rd UK Phenomenology
Workshop on HERA Physics, Durham, 20-25 Sep. 199
Barriers to HIV Testing in Côte d'Ivoire: The Role of Individual Characteristics and Testing Modalities
BACKGROUND: Expanding HIV testing requires a better understanding of barriers to its uptake. We investigated barriers to HIV testing in Côte d'Ivoire, taking into account test circumstances (client vs. provider-initiated). METHODS: We used data from the 2005 nationally representative Demographic and Health Survey conducted in Côte d'Ivoire. Socio-demographic characteristics, sexual behaviour and knowledge and attitudes toward HIV/AIDS associated with recent (<2 years) HIV testing were identified using gender-specific univariate and multivariate logistic regressions. Among women, differential effects of barriers to testing according to test circumstance (whether they have been offered for a prenatal test or not) were assessed through interaction tests. RESULTS: Recent HIV testing was reported by 6.1% of men and 9.5% of women (including 4.6% as part of antenatal care). Among men, having a low socioeconomic status, having a low HIV-related knowledge level and being employed [compared to those inactive: adjusted Odds Ratio (aOR) 0.46; 95% confidence interval (CI) 0.25-0.87] were associated with lower proportions of recent HIV testing. Among women without a prenatal HIV testing offer, living outside the capital (aOR 0.38; CI 0.19-0.77) and reporting a unique lifetime sexual partner constituted additional barriers to HIV testing. By contrast, among women recently offered to be tested in prenatal care, none of these variables was found to be associated with recent HIV testing. CONCLUSIONS: Various dimensions of individuals' characteristics constituted significant barriers to HIV testing in Côte d'Ivoire in 2005, with gender specificities. Such barriers are substantially reduced when testing was proposed in the framework of antenatal care. This suggests that provider-initiated testing strategies may help overcome individual barriers to HIV testing
Squark and Gluino Production at Hadron Colliders
We have determined the theoretical predictions for the cross-sections of
squark and gluino production at \ppb and colliders (Tevatron and LHC) in
next-to-leading order of supersymmetric QCD. By reducing the dependence on the
renormalization/factorization scale considerably, the theoretically predicted
values for the cross-sections are much more stable if these higher-order
corrections are implemented. If squarks and gluinos are discovered, this
improved stability translates into a reduced error on the masses, as extracted
experimentally from the size of the production cross-sections. The
cross-sections increase significantly if the next-to-leading order corrections
are included at a renormalization/factorization scale near the average mass of
the produced massive particles. This rise results in improved lower bounds on
squark and gluino masses. By contrast, the shape of the transverse-momentum and
rapidity distributions remains nearly unchanged when the next-to-leading order
corrections are included.Comment: 60 pages, Latex2e, 24 figures (uses epsfig.sty
The measurement of the Higgs self-coupling at the LHC: theoretical status
Now that the Higgs boson has been observed by the ATLAS and CMS experiments
at the LHC, the next important step would be to measure accurately its
properties to establish the details of the electroweak symmetry breaking
mechanism. Among the measurements which need to be performed, the determination
of the Higgs self-coupling in processes where the Higgs boson is produced in
pairs is of utmost importance. In this paper, we discuss the various processes
which allow for the measurement of the trilinear Higgs coupling: double Higgs
production in the gluon fusion, vector boson fusion, double Higgs-strahlung and
associated production with a top quark pair. We first evaluate the production
cross sections for these processes at the LHC with center-of-mass energies
ranging from the present TeV to TeV, and discuss
their sensitivity to the trilinear Higgs coupling. We include the various
higher order QCD radiative corrections, at next-to-leading order for gluon and
vector boson fusion and at next-to-next-to-leading order for associated double
Higgs production with a gauge boson. The theoretical uncertainties on these
cross sections are estimated. Finally, we discuss the various channels which
could allow for the detection of the double Higgs production signal at the LHC
and the accuracy on the self-coupling that could be ultimately achieved.Comment: 37 pages, 10 tables, 17 figures. Typos corrected, matches the journal
versio
QCD Corrections to SUSY Higgs Production: The Role of Squark Loops
We calculate the two-loop QCD corrections to the production of the neutral
supersymmetric Higgs bosons via the gluon fusion mechanism at hadron colliders,
including the contributions of squark loops. To a good approximation, these
additional contributions lead to the same QCD corrections as in the case where
only top and bottom quark loops are taken into account. The QCD corrections are
large and increase the Higgs production cross sections significantly.Comment: 5 pages, latex, 2 figure
H-->ggg(gqqbar) at Two Loops in the Large-M_t Limit
We present a calculation of the two-loop helicity amplitudes for the
processes H-->ggg and H-->gqqbar in the large-M_t limit. In this limit the
calculation can be performed in terms of one-loop diagrams containing an
effective Hgg operator. These amplitudes are required for the next-to-leading
order (NLO) corrections to the Higgs transverse momentum distribution and the
next-to-next-to-leading order (NNLO) corrections to the Higgs production cross
section via the gluon fusion mechanism.Comment: 13 pages Latex, 2 figure
SM and MSSM Higgs Boson Production: Spectra at large transverse Momentum
Strategies for Higgs boson searches require the knowledge of the total
production cross section and the transverse momentum spectrum. The large
transverse momentum spectrum of the Higgs boson produced in gluon fusion can be
quite different in the Standard Model and the Minimal Supersymmetric Standard
Model. In this paper we present a comparison of the Higgs transverse momentum
spectrum obtained using the PYTHIA event generator and the HIGLU program as
well as the program HQT, which includes NLO corrections and a soft gluon
resummation for the region of small transverse momenta. While the shapes of the
spectra are similar for the Standard Model, significant differences are
observed in the spectra of Minimal Supersymmetric Standard Model benchmark
scenarios with large tan(beta).Comment: 8 pages, 13 figure
Genetic Variation and Antioxidant Response Gene Expression in the Bronchial Airway Epithelium of Smokers at Risk for Lung Cancer
Prior microarray studies of smokers at high risk for lung cancer have demonstrated that heterogeneity in bronchial airway epithelial cell gene expression response to smoking can serve as an early diagnostic biomarker for lung cancer. As a first step in applying functional genomic analysis to population studies, we have examined the relationship between gene expression variation and genetic variation in a central molecular pathway (NRF2-mediated antioxidant response) associated with smoking exposure and lung cancer. We assessed global gene expression in histologically normal airway epithelial cells obtained at bronchoscopy from smokers who developed lung cancer (SC, n=20), smokers without lung cancer (SNC, n=24), and never smokers (NS, n=8). Functional enrichment analysis showed that the NRF2-mediated, antioxidant response element (ARE)-regulated genes, were significantly lower in SC, when compared with expression levels in SNC. Importantly, we found that the expression of MAFG (a binding partner of NRF2) was correlated with the expression of ARE genes, suggesting MAFG levels may limit target gene induction. Bioinformatically we identified single nucleotide polymorphisms (SNPs) in putative ARE genes and to test the impact of genetic variation, we genotyped these putative regulatory SNPs and other tag SNPs in selected NRF2 pathway genes. Sequencing MAFG locus, we identified 30 novel SNPs and two were associated with either gene expression or lung cancer status among smokers. This work demonstrates an analysis approach that integrates bioinformatics pathway and transcription factor binding site analysis with genotype, gene expression and disease status to identify SNPs that may be associated with individual differences in gene expression and/or cancer status in smokers. These polymorphisms might ultimately contribute to lung cancer risk via their effect on the airway gene expression response to tobacco-smoke exposure.Intramural Research Program of the National Institute of Environmental Health Sciences; National Institutes of Health (Z01 ES100475, U01ES016035, R01CA124640
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