1,415 research outputs found
Collider constraints on light pseudoscalars
We investigate the bounds on light pseudoscalars that arise from a variety of
collider searches. Special attention is thereby devoted to the mass regions
and , in which a meaningful
theoretical description has to include estimates of non-perturbative effects
such as the mixing of the pseudoscalar with QCD bound states. A compendium of
formulas that allows to deal with the relevant corrections is provided. It
should prove useful for the interpretation of future LHC searches for light
CP-odd spin-0 states.Comment: 17 pages, 3 figures, 2 tables; v3: new draft includes the constraints
from CMS-PAS-HIG-17-024 and CMS-PAS-HIG-17-029; a similar version has been
published in JHEP. also contained in arXiv:1803.1037
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
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
Heavy top limit and double-logarithmic contributions to Higgs production at m_H^2 / s << 1
Next-to-next-to-leading order (NNLO) QCD corrections to Higgs boson
hadroproduction have recently been calculated in the heavy top-quark limit m_t
-> \infty. The m_t -> \infty limit introduces double-logarithmic corrections in
ln x, with x = m_H^2 / s. We identify these corrections order by order in
alpha_s. As an application, we derive an analytic expression for the dominant x
<< 1 part of the NNLO coefficient.Comment: 7 page
Production of a Higgs pseudoscalar plus two jets in hadronic collisions
We consider the production of a Higgs pseudoscalar accompanied by two jets in
hadronic collisions. We work in the limit that the top quark is much heavier
than the Higgs pseudoscalar and use an effective Lagrangian for the
interactions of gluons with the pseudoscalar. We compute the amplitudes
involving: 1) four gluons and the pseudoscalar, 2) two quarks, two gluons and
the pseudoscalar and 3) four quarks and the pseudoscalar. We find that the
pseudoscalar amplitudes are nearly identical to those for the scalar case, the
only differences being the overall size and the relative signs between terms.
We present numerical cross sections for proton-proton collisions with
center-of-mass energy 14 TeV.Comment: 12 pages, LaTeX, 4 Postscript figures, submitted to Phys. Rev.
Measurement of the H/A -> tau tau cross section and possible constraints on tan beta
The achievable precision of the cross section times branching ratio
measurement from the event rates is estimated for the MSSM H/A -> tau tau decay
in the associated production process gg -> b bbar H/A at large tan beta in CMS.
This work demonstrates that the above production and decay process exhibit a
large sensitivity to tan beta and thus add as a significant observable to a
global fit of the SUSY parameters. To illustrate this potential an example is
given concerning the achievable tan beta determination accuracy that could be
reached from the event rates and for a given set of SUSY parameters and
uncertainties
Top quark associated production of topcolor pions at hadron colliders
We investigate the associated production of a neutral physical pion with top
quarks in the context of topcolor assisted technicolor. We find that single-top
associated production does not yield viable rates at either the Tevatron or
LHC. tt-associated production at the Tevatron is suppressed relative to
Standard Model ttH, but at the LHC is strongly enhanced and would allow for
easy observation of the main decay channels to bottom quarks, and possible
observation of the decay to gluons.Comment: 13 pages, 4 figures, submitted to PR
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