89 research outputs found
Pair production of charged MSSM Higgs bosons by gluon fusion
The production of pairs of charged Higgs bosons as predicted by the minimal
supersymmetric standard model (MSSM) via the gluon fusion mechanism is
investigated. The amplitudes at the leading one-loop order for the parton
process gg -> H+ H- are calculated with the complete set of MSSM particles.
Numerical results are presented for the cross section of the inclusive hadron
process p p -> gg -> H+ H- + X at the LHC.Comment: 25 pages, 7 figures, 3 typos corrected, acknowledgement added,
coincides now with published versio
Electroweak and Bottom Quark Contributions to Higgs Boson plus Jet Production
This paper presents predictions for jet pseudorapidity (eta) and transverse
momentum (p_T) distributions for the production of the Standard Model Higgs
boson in association with a high-p_T hadronic jet. We discuss the contributions
of electroweak loops and of bottom-quark parton processes to the cross section.
The latter arise in the five-flavour scheme. Predictions for the Tevatron and
the Large Hadron Collider with 10 TeV collision energy are presented. For Higgs
boson masses of 120 GeV, 160 GeV and 200 GeV, we find the maximal effects of
the electroweak contributions to the Higgs plus jet p_T and eta distribution to
be -14 % and -5.3 %, respectively, for the Tevatron, and -3 % and -2 %,
respectively, for the LHC. For the maximal contribution of bottom-quark parton
processes to the p_T and eta distribution, we find +3 % and + 2.5 %,
respectively, for the Tevatron, and +3.5 % and +3 %, respectively, for the LHC.
A separate study of the Higgs + b-jet cross section demonstrates that a
calculational approach which respects the hierarchies of Yukawa couplings
yields a leading order cross section prediction which is more accurate in the
high-p_T regime than conventional approaches.Comment: 25 pages, 14 figure
Enhancement of W+/- H-/+ Production at Hadron Colliders in the Two Higgs Doublet Model
We discuss the associated W+/- H-/+ production at the CERN Large Hadron
Collider. The dependence of the hadronic cross section on the Higgs sector
parameters is investigated in detail in the framework of the general Two Higgs
Doublet Model (THDM). We study the possible enhancement of the THDM prediction
for the cross section compared to the prediction of the Minimal Supersymmetric
Standard Model (MSSM). We find regions in the THDM parameter space where the
THDM prediction can exceed the one of the MSSM by two orders of magnitude.
These regions of large cross section are in agreement with theoretical bounds
on the model, derived from the requirement of vacuum stability and perturbative
unitarity, and are not excluded by experimental constraints.Comment: 19 pages, 5 figure
The gluon/charm content of the eta' meson and instantons
Motivated by recent CLEO measurements of the B-->\eta' K decay, we evaluate
gluon/charm content of the eta' meson using the interacting instanton liquid
model of the QCD vacuum. Our result is very large due to the strong field of
small-size instantons. We show that it provides quantitative explanations of
the CLEO data on the B-->\eta' K decay rate (as well as inclusive process
B-->\eta' X), via a virtual Cabbibo-unsuppressed decay into \bar c c pair which
then becomes eta'. If so, a significant charm component should be present in
other hadrons also. In particular, we found a large contribution of the charmed
quark in the polarised deep-inelastic scattering on a proton.Comment: 6 pages, LATE
Charged Higgs Bosons decays H^\pm \to W^\pm (\gamma, Z) revisited
We study the complete one loop contribution to H^\pm\to W^\pm V, V= Z,
\gamma, both in the Minimal Supersymmetric Standard Model (MSSM) and in the Two
Higgs Doublet Model (2HDM). We evaluate the MSSM contributions and compare them
with the 2HDM ones taking into account b\to s\gamma constraint, vacuum
stability and unitarity constraints in the case of 2HDM, as well as
experimental constraints on the MSSM and 2HDM parameters. In the MSSM, we found
that in the intermediate range of \tan\beta \la 10 and for large A_t, the
branching ratio of H^\pm \to W^{\pm} Z can be of the order 10^{-3} while the
branching ratio of H^\pm \to W^{\pm} \gamma is of the order 10^{-5}. We also
study the effects of the CP violating phases of Soft SUSY parameters and found
that they can modify the branching ratio by about one order of magnitude.
However, in the 2HDM where the Higgs sector is less constrained as compared to
the MSSM higgs sector, one can reach branching ratio of the order 10^{-2} for
both modes.Comment: 18 pages, 9 figure
Analytic Results for Higgs Production in Bottom Fusion
We evaluate analytically the cross section for Higgs production plus one jet
through bottom quark fusion. By considering the small pT limit we derive
expressions for the resummation coefficients governing the structure of large
logarithms, and compare these expressions with those available in the
literature.Comment: 14 pages, 7 figure
Higgs-Boson Production Induced by Bottom Quarks
Bottom quark-induced processes are responsible for a large fraction of the
LHC discovery potential, in particular for supersymmetric Higgs bosons.
Recently, the discrepancy between exclusive and inclusive Higgs boson
production rates has been linked to the choice of an appropriate bottom
factorization scale. We investigate the process kinematics at hadron colliders
and show that it leads to a considerable decrease in the bottom factorization
scale. This effect is the missing piece needed to understand the corresponding
higher order results. Our results hold generally for charged and for neutral
Higgs boson production at the LHC as well as at the Tevatron. The situation is
different for single top quark production, where we find no sizeable
suppression of the factorization scale. Turning the argument around, we can
specify how large the collinear logarithms are, which can be resummed using the
bottom parton picture.Comment: 18 page
Charged Higgs Boson Production in Bottom-Gluon Fusion
We compute the complete next-to-leading order SUSY-QCD corrections for the
associated production of a charged Higgs boson with a top quark via
bottom-gluon fusion. We investigate the applicability of the bottom parton
description in detail. The higher order corrections can be split into real and
virtual corrections for a general two Higgs doublet model and into additional
massive supersymmetric loop contributions. We find that the perturbative
behavior is well under control. The supersymmetric contributions consist of the
universal bottom Yukawa coupling corrections and non-factorizable diagrams.
Over most of the relevant supersymmetric parameter space the Yukawa coupling
corrections are sizeable, while the remaining supersymmetric loop contributions
are negligible.Comment: 18 pages, v2: some discussions added, v3: published versio
Charged Higgs production from SUSY particle cascade decays at the LHC
We analyze the cascade decays of the scalar quarks and gluinos of the Minimal
Supersymmetric extension of the Standard Model, which are abundantly produced
at the Large Hadron Collider, into heavier charginos and neutralinos which then
decay into the lighter ones and charged Higgs particles, and show that they can
have substantial branching fractions. The production rates of these Higgs
bosons can be much larger than those from the direct production mechanisms, in
particular for intermediate values of the parameter , and could
therefore allow for the detection of these particles. We also discuss charged
Higgs boson production from direct two-body top and bottom squark decays as
well as from two- and three-body gluino decays.Comment: 30 pages with 10 figures, latex. Uses axodraw.sty and epsfig.st
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