16 research outputs found
A Forward Branching Phase Space Generator for Hadron colliders
In this paper we develop a projective phase space generator appropriate for
hadron collider geometry. The generator integrates over bremsstrahlung events
which project back to a single, fixed Born event. The projection is dictated by
the experimental jet algorithm allowing for the forward branching phase space
generator to integrate out the jet masses and initial state radiation. When
integrating over the virtual and bremsstrahlung amplitudes this results in a
single K-factor, assigning an event probability to each Born event. This
K-factor is calculable as a perturbative expansion in the strong coupling
constant. One can build observables from the Born kinematics, giving identical
results to tradi- tional observables as long as the observable does not depend
on the infrared sensitive jet mass or initial state radiation.Comment: 16 pages, 10 figure
Charged Higgs-boson production in association with an electron and a neutrino at electron-positron colliders
We present results of a calculation of the cross section for the production
of a charged Higgs boson in association with an electron and a neutrino at
electron-positron colliders (e+ e- -> H+ e- nu_e-bar, H- e+ nu_e). We study
predictions for the cross section in the Minimal Supersymmetric Standard Model
(MSSM) and the Two Higgs Doublet Model (THDM), highlighting possible
differences. The process is effectively loop-induced in both models. Hence, the
cross section is expected to be strongly model-dependent. Most notably, due to
the presence of superpartners, the MSSM amplitude contains Feynman graphs of
pentagon-type, which are not present in the THDM. This is the first complete
one-loop calculation of the cross section for this process in the THDM and the
MSSM. For both models, so far, only approximate results with limited ranges of
validity were available. Our main aim here is to clarify several open questions
in the existing literature on this process. Specifically, we will discuss the
validity of the Heavy Fermion loop approximation in both models, and of the
Fermion/Sfermion loop approximation in the MSSM.Comment: 21 pages, 8 figures, 1 tabl
Stress-testing the VBF approximation in multijet final states
We consider electro-weak Higgs plus three jets production at NLO QCD beyond
strict VBF acceptance cuts. We investigate, for the first time, how accurate
the VBF approximation is in these regions and within perturbative
uncertainties, by a detailed comparison of full and approximate calculations.
We find that a rapidity gap between the tagging jets guarantees a good
approximation, while an invariant mass cut alone is not sufficient, which needs
to be confronted with experimental choices. We also find that a significant
part of the QCD corrections can be attributed to Higgs-Strahlungs-type
topologies.Comment: 6 pages, 5 figures, add VBSCAN report numbe
Next-to-leading order QCD corrections to light Higgs Pair production via vector boson fusion
We present the NLO QCD corrections for light Higgs pair production via vector
boson fusion at the LHC within the CP conserving type II two higgs doublet
model in the form of a fully flexible parton--level Monte Carlo program. Scale
dependences on integrated cross sections and distributions are reduced with QCD
K-factors of order unity.Comment: 16 pages, 10 figures, 3 table
Stress testing the vector-boson-fusion approximation in multijet final states
We consider electroweak Higgs plus three jets production at NLO QCD beyond strict VBF acceptance cuts. We investigate, for the first time, how accurate the VBF approximation is in these regions and within perturbative uncertainties by a detailed comparison of full and approximate calculations. We find that a rapidity gap between the tagging jets guarantees a good approximation, while an invariant mass cut alone is not sufficient, which needs to be confronted with experimental choices. We also find that a significant part of the QCD corrections can be attributed to Higgs-Strahlungs-type topologies
Next-to-leading order QCD corrections to Higgs boson production in association with a photon via weak-boson fusion at the LHC
Higgs boson production in association with a hard central photon and two
forward tagging jets is expected to provide valuable information on Higgs boson
couplings in a range where it is difficult to disentangle weak-boson fusion
processes from large QCD backgrounds. We present next-to-leading order QCD
corrections to Higgs production in association with a photon via weak-boson
fusion at a hadron collider in the form of a flexible parton-level Monte Carlo
program. The QCD corrections to integrated cross sections are found to be small
for experimentally relevant selection cuts, while the shape of kinematic
distributions can be distorted by up to 20% in some regions of phase space.
Residual scale uncertainties at next-to-leading order are at the few-percent
level.Comment: 17 pages, 7 figures, 1 tabl
The other Higgses, at resonance, in the Lee-Wick extension of the Standard Model
Within the framework of the Lee Wick Standard Model (LWSM) we investigate
Higgs pair production , and top pair
production at the Large Hadron Collider (LHC), where the
neutral particles from the Higgs sector (, and )
appear as possible resonant intermediate states. We investigate the signal and we find that the LW Higgs,
depending on its mass-range, can be seen not long after the LHC upgrade in
2012. More precisely this happens when the new LW Higgs states are below the
top pair threshold. In the LW states, due to the wrong-sign
propagator and negative width, lead to a dip-peak structure instead of the
usual peak-dip structure which gives a characteristic signal especially for
low-lying LW Higgs states. We comment on the LWSM and the forward-backward
asymmetry in view of the measurement at the TeVatron. Furthermore, we present a
technique which reduces the hyperbolic diagonalization to standard
diagonalization methods. We clarify issues of spurious phases in the Yukawa
sector.Comment: 36 pages, 16 figures, 3 table
NLO multijet merging for Higgs production beyond the VBF approximation
We present results of the simulation of electroweak Higgs boson production at the Large Hadron Collider using both the NLO multijet merging and NLO matching frameworks provided by the general purpose event generator Herwig 7. For the simulation of the hard scattering processes, we use the HJets library for the full calculation and VBFNLO for the approximate calculation to compute the amplitudes at tree-level with and at one-loop with
NLO QCD Corrections to Electroweak Higgs Boson Plus Three Jet Production at the LHC
The implementation of the full next-to-leading order (NLO) QCD corrections to electroweak Higgs boson plus three jet production at hadron colliders such as the LHC within the Matchbox NLO framework of the Herwig++ event generator is discussed. We present numerical results for integrated cross sections and kinematic distributions