57 research outputs found
Electroweak Precision Observables within a Fourth Generation Model with General Flavour Structure
We calculate the contributions to electroweak precision observables (EWPOs)
due to a fourth generation of fermions with the most general (quark-)flavour
structure (but assuming Dirac neutrinos and a trivial flavour structure in the
lepton sector). The new-physics contributions to the EWPOs are calculated at
one-loop order using automated tools (FeynArts/FormCalc). No further
approximations are made in our calculation. We discuss the size of non-oblique
contributions arising from Z--quark--anti-quark vertex corrections and the
dependence of the EWPOs on all CKM mixing angles involving the fourth
generation. We find that the electroweak precision observables are sensitive to
two of the fourth-generation mixing angles and that the corresponding
constraints on these angles are competitive with those obtained from flavour
physics. For non-trivial 4x4 flavour structures, the non-oblique contributions
lead to relative corrections of several permille and should be included in a
global fit
Super AutoDipole
The publicly available package for an automated dipole subtraction,
AutoDipole, is extended to include the SUSY dipoles in the MSSM. All fields in
the SM and the MSSM are available. The code is checked against the analytical
expressions for a simple process. The extended package makes it possible to
compute the QCD NLO corrections to SUSY multi-parton processes like the stop
pair production plus jets at the LHC.Comment: 16 pages, 1 figure, v2: a few typos to match the published version in
Eur. Phys. J.
Photon Radiation with MadDipole
We present the automation of a subtraction method for photon radiation using
the dipole formalism within the MadGraph framework. The subtraction terms are
implemented both in dimensional regularization and mass regularization for
massless and massive cases and non-collinear-safe observables are accounted
for.Comment: 23 pages, 2 figures, minor additions, references added, version
published in JHE
- …