1,894 research outputs found
The relevance of virtual electroweak effects in the overall -channel single top production at LHC
We compute the complete one loop electroweak effects in the MSSM for the
eight processes of single top (and single antitop) production in the
-channel at hadron colliders, generalizing a previous analysis performed for
the dominant final state. The results are quite similar for all processes,
showing an impressively large Standard Model effect and a generally modest
genuine SUSY contribution in the mSUGRA scenario. The one loop effect on the
total rate is shown and the possibility of measuring it at LHC is discussed.Comment: 15 pages, 7 eps figure
Associated production of charged Higgs and top at LHC: the role of the complete electroweak supersymmetric contribution
The process of charged Higgs production in association with a top quark at
the LHC has been calculated at the complete NLO electroweak level both in a Two
Higgs Doublets Model and in the Minimal Supersymmetric Standard Model, assuming
a mSUGRA breaking scheme. We have numerically explored the size of the one-loop
corrections in two typical supersymmetric scenarios, with particular attention
to the tan beta dependence, and we have found that they remain perturbatively
small but possibly sizable, reaching a 20% limit for extreme values of tan
beta, when the complete set of Feynman diagrams is taken into account.Comment: 22 pages, 5 figures, reference adde
Supersymmetry spectroscopy in stop-chargino production at LHC
We consider the process of associated stop-chargino production in the MSSM at
LHC and show that, at the simplest Born level, the production rate is
dramatically sensitive to the choice of the benchmark points, oscillating from
potentially "visible" maxima of the picobarn size to much smaller, hardly
"visible", values. Adopting a canonical choice of SM type CKM matrices, we also
show that in some "visible" cases the total rate exhibits a possibly relevant
dependence on tan(beta).Comment: 23 pages, 18 eps figure
Associated tW production at LHC: a complete calculation of electroweak supersymmetric effects at one loop
We compute, in the MSSM framework, the total electroweak contributions at one
loop for the process pp -> tW+X, initiated by the parton process bg -> tW. The
supersymmetric effect is analyzed for various choices of the SUSY benchmark
points. Choosing realistic unpolarized and polarized experimental quantities,
we show the size of the various effects and discuss their dependence on the
MSSM parameters.Comment: 32 pages, 9 eps figure
Semi-inclusive bottom-Higgs production at LHC: The complete one-loop electroweak effect in the MSSM
We present the first complete calculation of the one-loop electroweak effect
in the process of semi-inclusive bottom-Higgs production at LHC in the MSSM.
The size of the electroweak contribution depends on the choice of the final
produced neutral Higgs boson, and can be relevant, in some range of the input
parameters. A comparison of the one-loop results obtained in two different
renormalization schemes is also performed, showing a very good NLO scheme
independence. We further comment on two possible, simpler, approximations of
the full NLO result, and on their reliabilty
Weak Interaction Sum Rules for Polarized top-antitop Production at LHC
We consider two polarization asymmetries in the process of top-antitop
production at LHC. We show that the theoretical predictions for these two
quantities, at the strong and electroweak partonic one-loop level, are free of
QCD and QED effects. At this perturbative level we derive two sum rules, that
relate measurable quantities of top-antitop production to genuinely weak
inputs. This would allow to perform two independent tests of the candidate
theoretical model, with a precision that will be fixed by the future
experimental accuracies of the different polarization measurements. A tentative
quantitative illustration of this statement for a specific MSSM scenario is
enclosed, and a generalization to include two other future realistic
measurements is also proposed.Comment: 13 pages, 3 figures, local report number adde
Longitudinal Polarization at future Colliders and Virtual New Physics Effects
The theoretical merits of longitudinal polarization asymmetries of
electron-positron annihilation into two final fermions at future colliders are
examined, using a recently proposed theoretical description. A number of
interesting features, valid for searches of virtual effects of new physics, is
underlined, that is reminiscent of analogous properties valid on top of
resonance. As an application to a concrete example, we consider the case of a
model with triple anomalous gauge couplings and show that the additional
information provided by these asymmetries would lead to a drastic reduction of
the allowed domain of the relevant parameters.Comment: 18 pages and 1 figure. e-mail: [email protected]
Top quark production at future lepton colliders in the asymptotic regime
The production of a tt(bar) pair from lepton-antilepton annihilation is
considered for values of the center of mass energy much larger than the top
mass, typically of the few TeV size. In this regime a number of simplifications
occurs that allows to derive the leading asymptotic terms of various
observables using the same theoretical description that was used for light
quark production. Explicit examples are shown for the Standard Model and the
Minimal Supersymmetric Standard Model cases.Comment: 20 pages and 13 figures. e-mail: [email protected]
A complete one-loop calculation of electroweak supersymmetric effects in -channel single top production at LHC
We have computed the complete one-loop electroweak effects in the MSSM for
single top (and single antitop) production in the -channel at hadron
colliders, generalizing a previous analysis performed for the dominant
final state and fully including QED effects. The results are quite similar for
all processes. The overall Standard Model one-loop effect is small, of the few
percent size. This is due to a compensation of weak and QED contributions that
are of opposite sign. The genuine SUSY contribution is generally quite modest
in the mSUGRA scenario. The experimental observables would therefore only
practically depend, in this framework, on the CKM coupling.Comment: 25 pages, several eps figures. Update corresponding to published
versio
Single top production in the -channel at LHC: a realistic test of electroweak models
We compute the complete electroweak one-loop effect on the process of
-channel single top production at LHC in the Standard Model and in the MSSM
within the mSUGRA symmetry breaking scheme. We find that the one-loop
electroweak SM effect is large, and decreases the cross section of an amount
that is of the same size as that of the NLO QCD one. The genuine SUSY effect in
the mSUGRA scheme, for a general choice of benchmark points, is rather small.
It might become large and visible in more general scenarios around thresholds
involving light stop and neutralino mass values.Comment: 28 pages, 10 eps figure
- …