D. Zeppenfeld

University of Valencia, Valenza, Valencia, Spain

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Publications (189)391.39 Total impact

  • B. Jager, F. Schissler, D. Zeppenfeld
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    ABSTRACT: We present an implementation of Higgs boson production via vector-boson fusion in association with three jets at hadron colliders in the POWHEG-BOX, a framework for the matching of NLO-QCD calculations with parton-shower programs. Our work provides the means to precisely describe the properties of extra jet activity in vector-boson fusion reactions that are used for the suppression of QCD backgrounds by central jet veto techniques. For a representative setup at the CERN LHC we verify that uncertainties related to parton-shower effects are mild for distributions related to the third jet, in contrast to what has been observed in calculations based on vector-boson fusion induced Higgs production in association with two jets.
    05/2014;
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    ABSTRACT: VBFNLO is a flexible parton level Monte Carlo program for the simulation of vector boson fusion (VBF), double and triple vector boson (plus jet) production as well as QCD-induced single and double vector boson production plus two jets in hadronic collisions at next-to-leading order (NLO) in the strong coupling constant. Furthermore, Higgs boson plus two jet production via gluon fusion at the one-loop level is included. This note briefly describes the main additional features and processes that have been added in the new release -- VBFNLO Version 2.7.0. At NLO QCD several new processes are available. These are $W^\pm\gamma$ and $HH$ production in VBF, the QCD-induced single and double vector boson plus two jets processes $W^\pm jj$, $W^\pm Zjj$, $W^\pm\gamma jj$, same-sign $W^\pm W^\pm jj$, and the Higgs-strahlung process $W^\pm H$ (plus jet) production. Anomalous couplings are now available for all VBF, diboson and triboson (plus jet) processes including the new VBF $W^\pm\gamma jj$ implementation, as well as in the Higgs-strahlung (plus jet) process. Semi-leptonic decay modes are supported for the following diboson, triboson and VBF processes: $VV$, $VVV$, $VV\gamma$ production and $VV$ production via VBF, where $V$ denotes a massive gauge boson, i.e. $W^\pm$ or $Z$. Additionally, the VBF-Higgs production process with decay into $WW$ or $ZZ$ supports semi-leptonic decays of the gauge bosons. All these semi-leptonic processes contain the possibility to include anomalous gauge boson couplings.
    04/2014;
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    ABSTRACT: We present a study of $W^+W^+jj$ and $W^-W^-jj$ production including leptonic decays in hadron-hadron collisions. The full electroweak and QCD induced contributions and their interferences are calculated at leading order. We find that, for inclusive cuts, the interference effects can be large if the jets are produced with large transverse momentum where, however, the production rate is suppressed. We also discuss the vector-boson-fusion (VBF) cuts and show the validity of the VBF approximation. The NLO QCD corrections to the QCD-induced channels are also calculated. Compared to the previous calculation, we allow the intermediate $W$ bosons to be off-shell. For on-shell $W$ production, we obtain an excellent agreement with previous results. Our code will be publicly available as part of the parton level Monte Carlo program VBFNLO.
    Physical Review D 11/2013; 89(5):054009. · 4.69 Impact Factor
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    ABSTRACT: We present a summary of the first calculation of NLO QCD corrections to WZjj production with leptonic decays at the LHC. Our results show that the next-to-leading order corrections reduce significantly the scale uncertainties.
    10/2013;
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    Francisco Campanario, Nicolas Kaiser, Dieter Zeppenfeld
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    ABSTRACT: The next-to-leading order QCD corrections to W gamma production in association with two jets via vector boson fusion are calculated, including the leptonic decay of the W with full off-shell effects and spin correlations. The process lends itself to a test of quartic gauge couplings. The next-to-leading order corrections reduce the scale uncertainty significantly and show a non-trivial phase space dependence.
    Physical Review D 09/2013; 89(1):014009. · 4.69 Impact Factor
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    ABSTRACT: We report on the calculation of W^{±}Zjj production with leptonic decays at hadron-hadron colliders at next-to-leading order in QCD. These processes are important both to test the quartic gauge couplings of the standard model and because they constitute relevant backgrounds to beyond standard model physics searches. Our results show that the next-to-leading order corrections reduce significantly the scale uncertainties and have a nontrivial phase space dependence.
    Physical Review Letters 08/2013; 111(5):052003. · 7.73 Impact Factor
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    ABSTRACT: The status of di-boson and tri-boson production is shortly review. Using the VBFNLO and the LOOPSIM package, approximated results at NNLO QCD are given for WZ production. Results for waa + jet at NLO QCD are also shown.
    07/2013;
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    Jessica Frank, Michael Rauch, Dieter Zeppenfeld
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    ABSTRACT: After the discovery of the 126 GeV resonance at the LHC, the determination of its features, including its spin, is a very important ongoing task. In order to distinguish the two most likely spin hypotheses, spin-0 or spin-2, we study the phenomenology of a light Higgs-like spin-2 resonance produced in different gluon-fusion and vector-boson-fusion processes at the LHC. Starting from an effective model for the interaction of a spin-2 particle with the SM gauge bosons, we calculate cross sections and differential distributions within the Monte Carlo program Vbfnlo. We find that with specific model parameters such a spin-2 resonance can mimic SM Higgs rates and transverse-momentum distributions in $\gamma \gamma$, $WW$ and $ZZ$ decays, whereas several distributions allow to separate spin-2 from spin-0, independently of the spin-2 model parameters.
    05/2013;
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    Jessica Frank, Michael Rauch, Dieter Zeppenfeld
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    ABSTRACT: The most likely spin assignments of the recently discovered 126 GeV resonance are spin 0 or 2. In order to distinguish between the two, we construct an effective Lagrangian model that comprises interactions of a spin-2 electroweak singlet or triplet state with the Standard Model gauge bosons. Within this model, cross sections and differential distributions are calculated and implemented within the Monte Carlo program Vbfnlo, which simulates vector-boson-fusion processes at hadron colliders at next-to-leading order QCD accuracy. We study the phenomenology of spin-2 resonances produced in vector-boson-fusion processes at the LHC. Specifically, we consider light Higgs-like spin-2 resonances decaying into two photons and show how angular distributions allow us to distinguish between a Standard Model Higgs and a spin-2 resonance. We also investigate the characteristics of heavy spin-2 resonances that decay into two weak gauge bosons, leading to a four-lepton final state.
    Physical review D: Particles and fields 03/2013; 87(5).
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    Franziska Schissler, Dieter Zeppenfeld
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    ABSTRACT: We present the implementation of electroweak Zjj and Wjj production via vector boson fusion with fully leptonic decays at NLO QCD in the POWHEG framework. These processes represent an important background to Higgs searches in vector boson fusion, but they also can be seen as signal processes to study anomalous triple vector boson couplings as well as the impact of a central jet veto. Observables related to the third jet are sensitive to the parton shower which is used, a fact which is demonstrated by a comparison between PYTHIA, the standard angular-ordered HERWIG++ shower and the new p_T-ordered Dipole Shower in HERWIG++.
    Journal of High Energy Physics 02/2013; 2013(4). · 5.62 Impact Factor
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    ABSTRACT: Vbfnlo is a flexible parton level Monte Carlo program for the simulation of vector boson fusion (VBF), double and triple vector boson (plus jet) production in hadronic collisions at next-to-leading order (NLO) in the strong coupling constant, as well as Higgs boson plus two jet production via gluon fusion at the one-loop level. This note briefly describes the main additional features and processes that have been added in the new release -- Vbfnlo Version 2.6.0. At NLO QCD diboson production (W\gamma, WZ, ZZ, Z\gamma and \gamma\gamma), same-sign W pair production via vector boson fusion and the process W\gamma\gamma j have been implemented (for which one-loop tensor integrals up to six-point functions are included). In addition, gluon induced diboson production can be studied separately at the leading order (one-loop) level. The diboson processes WW, WZ and W\gamma can be run with anomalous gauge boson couplings, and anomalous couplings between a Higgs and a pair of gauge bosons is included in WW, ZZ, Z\gamma and \gamma\gamma diboson production. The code has also been extended to include anomalous gauge boson couplings for single vector boson production via VBF, and a spin-2 model has been implemented for diboson pair production via vector boson fusion.
    07/2012;
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    Bastian Feigl, Heidi Rzehak, Dieter Zeppenfeld
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    ABSTRACT: The searches for H -> WW events at the LHC use data driven techniques for estimating the q qbar -> WW background, by normalizing the background cross section to data in a control region. We investigate the possibility that new physics sources which mainly contribute to the control region lead to an overestimate of Standard Model backgrounds to the Higgs boson signal and, thus, to an underestimate of the H -> WW signal. A supersymmetric scenario with heavy squarks and gluinos but charginos in the 200 to 300 GeV region and somewhat lighter sleptons can lead to such a situation.
    Physics Letters B 05/2012; 717(s 4–5). · 4.57 Impact Factor
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    ABSTRACT: We present recent results in precision multiboson (+jet) phenomenology at the LHC. Results for diboson + jet, triboson, and also for WAA + jet will be discussed focusing on the impact of the perturbative corrections on the expected phenomenology.
    05/2012;
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    ABSTRACT: We review recent results in precision multiboson+jet phenomenology at the LHC. We discuss strategies how to compute these processes at NLO QCD and examine the impact of the perturbative corrections on the expected phenomenology, especially in the context of anomalous gauge boson couplings searches.
    12/2011;
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    F. Campanario, M. Kubocz, D. Zeppenfeld
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    ABSTRACT: In high energy hadronic collisions, a scalar or pseudoscalar Higgs boson, Φ=H, A, can be efficiently produced via gluon fusion, which is mediated by heavy quark loops. In this paper, we consider double real emission corrections to Φ=A production, which lead to a Higgs plus two-jet final state, at order αs4. Full quark mass effects are considered in the calculation of scattering amplitudes for the CP-odd Higgs boson A, as induced by quark triangle-, box-, and pentagon-diagrams. They complement the analogous results for a CP-even Higgs boson H in Ref. 1. Interference effects between loops with top and bottom quarks as well as between CP-even and CP-odd couplings of the heavy quarks are fully taken into account.
    Physical Review D 11/2011; 84(9). · 4.69 Impact Factor
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    G. Bozzi, F. Campanario, M. Rauch, D. Zeppenfeld
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    ABSTRACT: We present a calculation of the O(αs) QCD corrections to the production of a Z boson in association with two photons and to triple-photon production at hadron colliders. All final-state photons are taken as real. For the Z boson, we consider the decays both into charged leptons and into neutrinos including all off-shell effects. Numerical results are obtained via a Monte Carlo program based on the structure of the VBFNLO program package. This allows us to implement general cuts and distributions of the final-state particles. We find that the next-to-leading order QCD corrections are sizable and significantly exceed the expectations from a scale variation of the leading-order result. In addition, differential distributions of important observables change considerably. The prediction of two-photon-associated Z production with Z decays into neutrinos from the charged-lepton rate works well, once we use an additional cut on the invariant mass of the charged-lepton pair.
    Physical Review D 10/2011; 84(7). · 4.69 Impact Factor
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    Ken Arnold, Terrance Figy, Barbara Jager, Dieter Zeppenfeld
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    ABSTRACT: We present next-to-leading order QCD corrections to Higgs production in association with a photon via weak boson fusion at a hadron collider. Utilizing the fully flexible parton level Monte-Carlo program VBFNLO, we find small overall corrections, while the shape of some distributions is sensitive to radiative contributions in certain regions of phase-space. Residual scale uncertainties at next-to-leading order are at the few-percent level. Being perturbatively well under control and exhibiting kinematic features that allow to distinguish it from potential backgrounds, this process can serve as a valuable source of information on the $Hb\bar{b}$ Yukawa coupling.
    10/2011;
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    Bastian Feigl, Heidi Rzehak, Dieter Zeppenfeld
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    ABSTRACT: Within the Minimal Supersymmetric Standard Model (MSSM) the production and decay of superpartners can give rise to backgrounds for Higgs boson searches. Here MSSM background processes to the vector boson fusion channel with the Higgs boson decaying into two tau leptons or two W-bosons are investigated, giving rise to dilepton plus missing transverse momentum signals of the Higgs boson. Starting from a scenario with relatively small masses of the supersymmetric (SUSY) particles, with concomitant large cross section of the background processes, one obtains a first conservative estimate of the background. Light chargino pair production plus two jets, lightest and next-to-lightest neutralino production plus two jets as well as slepton pair production plus two jets are identified as important contributions to the irreducible SUSY background. Light chargino and next-to-lightest neutralino production plus two jets and next-to-lightest neutralino pair production plus two jets give rise to reducible backgrounds, which can be larger than the irreducible ones in some scenarios. The relevant distributions are shown and additional cuts for MSSM background reduction are discussed. Extrapolation to larger squark masses is performed and shows that MSSM backgrounds are quite small for squark masses at the current exclusion limits.
    European Physical Journal C 08/2011; · 5.25 Impact Factor
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    ABSTRACT: Vbfnlo is a flexible parton level Monte Carlo program for the simulation of vector boson fusion (VBF), double and triple vector boson production (plus jet) in hadronic collisions at next-to-leading order (NLO) in the strong coupling constant, as well as Higgs boson plus two jet production via gluon fusion at the one-loop level. In the new release -- Version 2.6.0 -- several new processes have been added at NLO QCD: diboson production W\gamma, WZ, ZZ, Z\gamma and \gamma\gamma), same-sign W pair production via vector boson fusion and the triboson plus jet process W\gamma\gamma j. In addition, gluon induced diboson production has been implemented at the leading order (one-loop) level. The diboson processes WW, WZ and W\gamma can be run with anomalous gauge boson couplings, and anomalous couplings between a Higgs and a pair of gauge bosons is included in WW, ZZ, Z\gamma and \gamma\gamma diboson production. The code has also been extended to include anomalous couplings for single vector boson production via VBF, and a spin-2 model has been implemented for diboson pair production via vector boson fusion.
    07/2011;
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    ABSTRACT: In this letter we report on a calculation of W gamma gamma + jet production at next-to-leading order QCD. We include the leptonic decays of the W and take into account all off-shell and finite width effects. This is the first computation which falls into the category of triboson+jet production at next-to-leading order QCD. In total we find sizable corrections with nontrivial phase space dependencies. Therefore, our results are important for phenomenological analyses such as the extraction of anomalous electroweak quartic couplings from inclusive hadron collider data.
    Physics Letters B 06/2011; 704(5). · 4.57 Impact Factor

Publication Stats

6k Citations
391.39 Total Impact Points

Institutions

  • 2013
    • University of Valencia
      Valenza, Valencia, Spain
  • 2006–2013
    • Karlsruhe Institute of Technology
      • Institute of Theoretical Physics
      Carlsruhe, Baden-Württemberg, Germany
  • 1988–2004
    • University of Wisconsin, Madison
      • Department of Physics
      Madison, MS, United States
  • 2001
    • Michigan State University
      • Department of Physics and Astronomy
      East Lansing, MI, United States
  • 1988–2000
    • CERN
      • Physics Department (PH)
      Genève, Geneva, Switzerland
  • 1989–1999
    • Florida State University
      • Department of Physics
      Tallahassee, FL, United States
  • 1992–1997
    • The University of Tokyo
      • Department of Physics
      Edo, Tōkyō, Japan
    • São Paulo State University
      • Institute for Theoretical Physics
      São Paulo, Estado de Sao Paulo, Brazil
    • University of Oxford
      • Department of Physics
      Oxford, England, United Kingdom
  • 1993
    • Argonne National Laboratory
      Lemont, Illinois, United States
  • 1986–1991
    • Durham University
      • Department of Physics
      Durham, ENG, United Kingdom
  • 1985–1988
    • Deutsches Elektronen-Synchrotron
      Hamburg, Hamburg, Germany