Juergen Reuter
University of Freiburg
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Juergen Reuter.
Journal of High Energy Physics | 2008
Ana Alboteanu; W. Kilian; Juergen Reuter
A crucial test of the Standard Model is the measurement of electroweak gauge-boson scattering. In this paper, we describe a generic parameterization aimed at a realistic simulation of weak-boson scattering at the LHC. The parameterization implements resonances of all possible spin and isospin combinations, properly matched to the low-energy effective (chiral) Lagrangian, includes leading higher-order effects and contains a minimal unitarization scheme. We implement the parameterization in the Monte-Carlo event generator WHIZARD and present results for complete partonic cross-section integration and event generation. We provide a comparison with the effective W approximation that previously has been used for most WW scattering studies at hadron colliders.
Physical Review D | 2004
Thorsten Ohl; Juergen Reuter
Extensions of the Standard Model of elementary particle physics to noncommutative geometries have been proposed as a low-energy limit of string models. Independent of this motivation, one may consider such a model as an effective field theory with higher-dimensional operators containing an antisymmetric rank-two background field. We study the signals of such a Noncommutative Standard Model (NCSM) and analyze the discovery potential of a future photon collider, considering angular distributions in fermion pair production.
Physical Review D | 2005
W. Kilian; D. Rainwater; Juergen Reuter
A motivation for physics beyond the Standard Model (SM) in the electroweak (EW) sector lies in the vast difference between the Planck (or unification) and the EW scale (hierarchy problem), that requires some stabilization of light scalar masses (fine tuning problem). In contrast to the supersymmetric solution to that problem where the quadratic sensitivity of the scalar masses to the cut-off is cancelled above the SUSY breaking scale between partners of opposite statistics, models have been constructed that contain a spontaneously broken global symmetry with the Higgs being light because it is one of the Goldstone bosons appearing in this breaking. In the simplest variant this construction fails because the scale for new strong interactions is too close to the electroweak scale, leaving traces in the low-energy effective action which would have shown up at LEP and Tevatron. There are two ways to evade these complications, either to use non-simple global groups (deconstruction models) or to entangle the global with the local symmetry breaking to forbid one-loop contributions to the Higgs mass parameters [1]. This shifts the scale where new strong dynamics naturally appears by one order of magnitude upwards. If the Higgs is among the Goldstone bosons of a broken global symmetry group, one always has a reduction of the rank of the global group. The Higgs thereby corresponds to a broken non-diagonal generator like the kaon in chiral symmetry breaking.
European Physical Journal C | 2006
W. Kilian; Juergen Reuter; T. Robens
We present a Monte Carlo event generator for simulating chargino pair production at the International Linear Collider (ILC) at next-to-leading order in the electroweak couplings. By properly resumming photons in the soft and collinear regions, we avoid negative event weights, so the program can simulate physical (unweighted) event samples. Photons are explicitly generated throughout the range where they can be experimentally resolved. Inspecting the dependence on the cutoffs separating the soft and collinear regions, we evaluate the systematic errors due to soft and collinear approximations. In the resummation approach, the residual uncertainty can be brought down to the per-mil level, coinciding with the expected statistical uncertainty at the ILC.
European Physical Journal C | 2006
M. Beyer; W. Kilian; P. Krstonošić; K. Mönig; Juergen Reuter; E. Schmidt; H. Schröder
We present a study of the sensitivity of the International Linear Collider (ILC) to electroweak parameters in the absence of a light Higgs boson. In particular, we consider those parameters that have been inaccessible at previous colliders, quartic gauge couplings. Within a generic effective-field theory context we analyze all processes that contain quasi-elastic weak-boson scattering, using complete six-fermion matrix elements in unweighted event samples, fast simulation of the ILC detector, and a multi-dimensional parameter fit of the set of anomalous couplings. The analysis does not rely on simplifying assumptions such as custodial symmetry or approximations such as the equivalence theorem. We supplement this by a similar new study of triple weak-boson production, which is sensitive to the same set of anomalous couplings. Including the known results on triple gauge couplings and oblique corrections, we thus quantitatively determine the indirect sensitivity of the ILC to new physics in the electroweak symmetry-breaking sector, conveniently parameterized by real or fictitious resonances in each accessible spin/isospin channel.
Physical Review D | 2006
W. Kilian; D. Rainwater; Juergen Reuter
We propose a means to discriminate between the two basic variants of Little Higgs models, the Product Group and Simple Group models, at the next generation of colliders. It relies on a special coupling of light pseudoscalar particles present in Little Higgs models, the pseudo-axions, to the Z and the Higgs boson, which is present only in Simple Group models. We discuss the collider phenomenology of the pseudo-axion in the presence of such a coupling at the LHC, where resonant production and decay of either the Higgs or the pseudo-axion induced by that coupling can be observed for much of parameter space. The full allowed range of parameters, including regions where the observability is limited at the LHC, is covered by a future ILC, where double scalar production would be a golden channel to look for.
Journal of High Energy Physics | 2010
Felix Braam; Alexander Knochel; Juergen Reuter
We propose a class of E6-based local orbifold Grand Unified Theories (GUTs) which yield an exceptional supersymmetric standard model as their low energy theory including leptoquark and un-Higgs exotics and a Z’ at the TeV scale. Unification is achieved in two steps through an intermediate scale symmetry breaking at a unified coupling which is enhanced due to the contributions of leptoquarks to the QCD beta function.
Journal of High Energy Physics | 2008
J. Kalinowski; W. Kilian; Juergen Reuter; T. Robens; Krzysztof Rolbiecki
For points in SUSY parameter space where the sneutrino is lighter than the lightest chargino and next-to-lightest neutralino, its direct mass determination from sneu- trino pair production process at e + e − collider is impossible since it decays invisibly. In such a scenario the sneutrino can be discovered and its mass determined from measurements of two-body decays of charginos produced in pairs at the ILC. Using the event generator WHIZARD we study the prospects of measuring sneutrino properties in a realistic ILC environment. In our analysis we include beamstrahlung, initial state radiation, a complete account of reducible backgrounds from SM and SUSY processes, and a complete matrix- element calculation of the SUSY signal which encompasses all irreducible background and interference contributions. We also simulate photon induced background processes using exact matrix elements. Radiation effects and the cuts to reduce background strongly mod- ify the edges of the lepton energy spectra from which the sneutrino and chargino mass are determined. We discuss possible approaches to measure the sneutrino mass with optimal precision.
European Physical Journal C | 2003
Thorsten Ohl; Juergen Reuter
Abstract.We study the cancellations among Feynman diagrams that implement the Ward and Slavnov-Taylor identities corresponding to the conserved supersymmetry current in supersymmetric quantum field theories. In particular, we show that the Faddeev-Popov ghosts of gauge and supersymmetries never decouple from the physical fields, even for abelian gauge groups. The supersymmetric Slavnov-Taylor identities provide efficient consistency checks for automatized calculations and can verify the supersymmetry of Feynman rules and the numerical stability of phenomenological predictions simultaneously.
arXiv: High Energy Physics - Phenomenology | 2016
Christian Weiss; Bijan Chokoufe; Juergen Reuter; W. Kilian
We briefly discuss the current status of NLO QCD automation in the Monte Carlo event generator WHIZARD. The functionality is presented for the explicit study of off-shell top quark production with associated backgrounds at a lepton collider.