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Sep 21, 2013
09/13

by
Ansgar Denner

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We review the techniques necessary for the calculation of virtual electroweak and soft photonic corrections at the one-loop level. In particular we describe renormalization, calculation of one-loop integrals and evaluation of one-loop Feynman amplitudes. We summarize many explicit results of general relevance. We give the Feynman rules and the explicit form of the counter terms of the electroweak standard model, we list analytical expressions for scalar one-loop integrals and reduction of...

Source: http://arxiv.org/abs/0709.1075v1

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89

Sep 18, 2013
09/13

by
Ansgar Denner

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For energies far above the electroweak scale, large electroweak radiative corrections occur that grow logarithmically with energy and can easily reach several tens of per cent in the TeV range. Recent work on these corrections is reviewed.

Source: http://arxiv.org/abs/hep-ph/0110155v1

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54

Sep 20, 2013
09/13

by
Ansgar Denner; Stefan Dittmaier

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In contrast to the conventional treatment of gauge theories, in the background-field method the Ward identities for connected Green functions are not violated by Dyson summation of self-energies in finite orders of perturbation theory. Thus, Dyson summation does not spoil gauge cancelations at high energies which are ruled by the Goldstone-boson equivalence theorem. Moreover, in the background-field method the precise formulation of the equivalence theorem in higher orders (including questions...

Source: http://arxiv.org/abs/hep-ph/9603341v2

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47

Sep 18, 2013
09/13

by
Ansgar Denner; Stefano Pozzorini

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We summarize results for the complete one-loop electroweak logarithmic corrections for general processes at high energies and fixed angles. Our results are applicable to arbitrary matrix elements that are not mass-suppressed. We give explicit results for W-boson-pair production in e^+e^- annihilation.

Source: http://arxiv.org/abs/hep-ph/0101213v2

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43

Sep 19, 2013
09/13

by
Ansgar Denner; Stefano Pozzorini

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We present results for the complete one-loop electroweak logarithmic corrections for general processes at high energies and fixed angles. Our results are applicable to arbitrary matrix elements that are not mass-suppressed. We give explicit results for 4-fermion processes and gauge-boson-pair production in electron-positron annihilation.

Source: http://arxiv.org/abs/hep-ph/0010201v3

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42

Sep 21, 2013
09/13

by
Ansgar Denner; Stefano Pozzorini

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We discuss the evaluation of the collinear single-logarithmic contributions to virtual electroweak corrections at high energies. More precisely, we proof the factorization of the mass singularities originating from loop diagrams involving collinear virtual gauge bosons coupled to external legs. We discuss, in particular, processes involving external longitudinal gauge bosons, which are treated using the Goldstone-boson equivalence theorem. The proof of factorization is performed within the 't...

Source: http://arxiv.org/abs/hep-ph/0104127v1

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59

Sep 23, 2013
09/13

by
Wim Beenakker; Ansgar Denner

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We give an overview of the problems and developments associated with the calculation of radiative corrections to off-shell gauge-boson pair production in e^+ e^- collisions.

Source: http://arxiv.org/abs/hep-ph/9806475v1

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19

Jun 28, 2018
06/18

by
Ansgar Denner; Robert Feger

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We compute the hadronic production of top-antitop pairs in association with a Higgs boson at next-to-leading-order QCD, including the decay of the top and antitop quark into bottom quarks and leptons. Our computation is based on full leading and next-to-leading-order matrix elements for $e^+ \nu_e \mu^-\bar{\nu}_\mu b \bar{b} H(j)$ and includes all non-resonant contributions, off-shell effects and interferences. Numerical results for the integrated cross section and several differential...

Topic: High Energy Physics - Phenomenology

Source: http://arxiv.org/abs/1506.07448

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43

Sep 22, 2013
09/13

by
Ansgar Denner; Stefano Pozzorini

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The cross section for $e^-e^- \to e^-e^-$ with arbitrary electron polarizations is calculated within the Electroweak Standard Model for energies large compared to the electron mass, including the complete virtual and soft-photonic $O(\alpha)$ radiative corrections. The relevant analytical results are listed, and a numerical evaluation is presented for the unpolarized and polarized cross sections as well as for polarization asymmetries. The relative weak corrections are typically of the order of...

Source: http://arxiv.org/abs/hep-ph/9807446v1

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8.0

Jun 29, 2018
06/18

by
Ansgar Denner; Mathieu Pellen

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For the first time the next-to-leading-order electroweak corrections to the full off-shell production of two top quarks that decay leptonically are presented. This calculation includes all off-shell, non-resonant, and interference effects for the 6-particle phase space. While the electroweak corrections are below one per cent for the integrated cross section, they reach up to 15% in the high-transverse-momentum region of distributions. To support the results of the complete one-loop...

Topic: High Energy Physics - Phenomenology

Source: http://arxiv.org/abs/1607.05571

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5.0

Jun 30, 2018
06/18

by
Ansgar Denner; Jean-Nicolas Lang

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We investigate unitarity within the Complex-Mass Scheme, a convenient universal scheme for perturbative calculations involving unstable particles in Quantum Field Theory which guarantees exact gauge invariance. Since this scheme requires to introduce complex masses and complex couplings, the Cutkosky cutting rules, which express perturbative unitarity in theories of stable particles, are no longer valid. We derive corresponding rules for scalar theories with unstable particles based on...

Topics: High Energy Physics - Theory, High Energy Physics - Phenomenology

Source: http://arxiv.org/abs/1406.6280

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102

Sep 23, 2013
09/13

by
Mariano Ciccolini; Ansgar Denner; Stefan Dittmaier

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The radiative corrections of the strong and electroweak interactions are calculated at next-to-leading order for Higgs-boson production in the weak-boson-fusion channel at hadron colliders. Specifically, the calculation includes all weak-boson fusion and quark--antiquark annihilation diagrams to Higgs-boson production in association with two hard jets, including all corresponding interferences. The results on the QCD corrections confirm that previously made approximations of neglecting...

Source: http://arxiv.org/abs/0710.4749v1

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Sep 18, 2013
09/13

by
Elena Accomando; Ansgar Denner; Stefano Pozzorini

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We have studied the effect of one-loop logarithmic electroweak radiative corrections on WZ and $W\gamma$ production processes at the LHC. We present analytical results for the leading-logarithmic electroweak corrections to the corresponding partonic processes du -> WZ, Wgamma. Using the leading-pole approximation we implement these corrections into Monte Carlo programs for $pp\to l\nu_l l'\bar l', l\nu_l\gamma$. We find that electroweak corrections lower the predictions by 5-20% in the...

Source: http://arxiv.org/abs/hep-ph/0110114v2

6
6.0

Jun 30, 2018
06/18

by
Ansgar Denner; Robert Feger; Andreas Scharf

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We present an analysis of Higgs-boson production in association with a top-quark pair at the LHC investigating in particular the final state consisting of four b jets, two jets, one identified charged lepton and missing energy. We consider the Standard Model prediction in three scenarios, the resonant Higgs-boson plus top-quark-pair production, the resonant production of a top-quark pair in association with a b-jet pair and the full process including all non-resonant and interference...

Topic: High Energy Physics - Phenomenology

Source: http://arxiv.org/abs/1412.5290

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55

Sep 22, 2013
09/13

by
Ansgar Denner; Stefan Dittmaier; Georg Weiglein

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The application of the background-field method to the electroweak Standard Model is reviewed and further explored. Special emphasis is put on questions of gauge invariance and gauge-parameter (in-)dependence. Owing to the gauge invariance of the background-field effective action, the vertex functions obey simple Ward identities which imply important properties of the vertex functions. Carrying out the renormalization in a way respecting background-field gauge invariance leads to considerable...

Source: http://arxiv.org/abs/hep-ph/9505271v1

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41

Sep 18, 2013
09/13

by
Mariano Ciccolini; Ansgar Denner; Stefan Dittmaier

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We present results on the strong and electroweak NLO corrections to the production of a Higgs boson plus two hard jets via weak interactions at the LHC. The calculation includes all weak-boson fusion and quark-antiquark annihilation diagrams as well as all related interferences. We discuss corrections of different origin (QCD corrections of vector-boson-fusion type and interferences, electroweak corrections induced by quark or photonic initial states, heavy-Higgs-boson effects, etc.) and give...

Source: http://arxiv.org/abs/0806.3624v1

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62

Sep 18, 2013
09/13

by
Ansgar Denner; Bernd Jantzen; Stefano Pozzorini

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We derive logarithmically enhanced two-loop virtual electroweak corrections for arbitrary fermion-scattering processes at the TeV scale. This extends results previously obtained for massless fermion scattering to processes that involve also bottom and top quarks. The contributions resulting from soft, collinear, and ultraviolet singularities in the complete electroweak Standard Model are explicitly extracted from two-loop diagrams to next-to-leading-logarithmic accuracy including all effects...

Source: http://arxiv.org/abs/0809.0800v2

6
6.0

Jun 28, 2018
06/18

by
Ansgar Denner; Robert Feger; Andreas Scharf

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We analyse the production of a Higgs boson in association with a top--antitop-quark pair in the Standard Model at the LHC. Considering the final state consisting of four b jets, two jets, one identified charged lepton and missing energy, we examine the irreducible background for the production rate and several kinematical distributions. While ttH production and decay is roughly a fourth of the full process for the final state specified above, ttbb production constitutes the main contribution...

Topic: High Energy Physics - Phenomenology

Source: http://arxiv.org/abs/1511.09344

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4.0

Jun 30, 2018
06/18

by
Ansgar Denner; Stefan Dittmaier; Lars Hofer

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We introduce the fortran-library COLLIER for the numerical evaluation of one-loop scalar and tensor integrals in perturbative relativistic quantum field theories. Important features are the implementation of dedicated methods to achieve numerical stability for 3- and 4-point tensor integrals, the support of complex masses for internal particles, and the possibility to choose between dimensional and mass regularization for infrared singularities. COLLIER supports one-loop N-point functions up to...

Topic: High Energy Physics - Phenomenology

Source: http://arxiv.org/abs/1407.0087

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52

Sep 18, 2013
09/13

by
Ansgar Denner; Lucia Hosekova; Stefan Kallweit

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We present a next-to-leading-order QCD calculation for e+\nu e\mu+\nu\mu jj production in vector-boson fusion, i.e. the scattering of two positively charged W bosons at the LHC. We include the complete set of electroweak leading-order diagrams for the six-particle final state and quantitatively assess the size of the s-channel and interference contributions in VBF kinematics. The calculation uses the complex-mass scheme to describe the W-boson resonances and is implemented into a flexible Monte...

Source: http://arxiv.org/abs/1209.2389v1

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5.0

Jun 29, 2018
06/18

by
Ansgar Denner; Stefan Dittmaier; Lars Hofer

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We present the library Collier for the numerical evaluation of one-loop scalar and tensor integrals in perturbative relativistic quantum field theories. The code provides numerical results for arbitrary tensor and scalar integrals for scattering processes in general quantum field theories. For tensor integrals either the coefficients in a covariant decomposition or the tensor components themselves are provided. Collier supports complex masses, which are needed in calculations involving unstable...

Topic: High Energy Physics - Phenomenology

Source: http://arxiv.org/abs/1604.06792

54
54

Sep 21, 2013
09/13

by
Mariano Ciccolini; Ansgar Denner; Stefan Dittmaier

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Radiative corrections of strong and electroweak interactions are presented at next-to-leading order for Higgs-boson production in the weak-boson-fusion channel at the LHC. The calculation includes all weak-boson fusion and quark-antiquark annihilation diagrams as well as all related interferences. The electroweak corrections, which also include real corrections from incoming photons and leading heavy-Higgs-boson effects at two-loop order, are of the same size as the QCD corrections, viz....

Source: http://arxiv.org/abs/0712.2895v1

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Jul 24, 2013
07/13

by
Axel Bredenstein; Ansgar Denner; Stefan Dittmaier; Stefano Pozzorini

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The process pp -> top anti-top bottom anti-bottom + X represents a very important background reaction to searches at the LHC, in particular to top anti-top H production where the Higgs boson decays into a bottom anti-bottom pair. A successful analysis of top anti-top H at the LHC requires the knowledge of direct top anti-top bottom anti-bottom production at next-to-leading order in QCD. We take the first step in this direction upon calculating the next-to-leading-order QCD corrections to the...

Source: http://arxiv.org/abs/0807.1248v1

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48

Sep 22, 2013
09/13

by
Ansgar Denner; Stefan Dittmaier; Tobias Kasprzik; Alexander Mück

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We present the first calculation of the next-to-leading-order electroweak corrections to W-boson + jet hadroproduction including leptonic W-boson decays. The W-boson resonance is treated consistently using the complex-mass scheme, and all off-shell effects are taken into account. The corresponding next-to-leading-order QCD corrections have also been recalculated. All the results are implemented in a flexible Monte Carlo code. Numerical results for cross sections and distributions of this...

Source: http://arxiv.org/abs/0906.1656v2

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60

Jul 24, 2013
07/13

by
Axel Bredenstein; Ansgar Denner; Stefan Dittmaier; Stefano Pozzorini

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The process pp -> top anti-top bottom anti-bottom + X represents a very important background reaction to searches at the LHC, in particular to top anti-top H production where the Higgs boson decays into a bottom anti-bottom pair. A successful analysis of top anti-top H at the LHC requires the knowledge of direct top anti-top bottom anti-bottom production at NLO in QCD. We take the first step in this direction upon calculating the NLO QCD corrections to the subprocess initiated by quark...

Source: http://arxiv.org/abs/0807.1453v1

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7.0

Jun 30, 2018
06/18

by
Ansgar Denner; Lars Hofer; Andreas Scharf; Sandro Uccirati

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We compute the next-to-leading order corrections of $O(\alpha_s^2\alpha^3)$ to the hadronic production of two oppositely charged leptons and two hard jets, $p p \to j j l^- l^+$, using Recola and Collier. We include electroweak and QCD corrections at the given order and all off-shell effects. We provide detailed predictions for the LHC operating at 13 TeV and obtain per-cent-level corrections for the total cross section. For differential distributions we find significant non-uniform distortions...

Topics: High Energy Physics - Phenomenology, High Energy Physics - Experiment

Source: http://arxiv.org/abs/1411.0916

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52

Sep 22, 2013
09/13

by
Ansgar Denner; Stefan Dittmaier; Tobias Kasprzik; Alexander Mück

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In this talk we discuss the next-to-leading-order electroweak (EW) corrections to W-boson + jet hadroproduction [1] and compare the full result to a simple approximation assuming factorization of EW and QCD corrections for the charged-current Drell-Yan process. The W-boson resonance is treated consistently using the complex-mass scheme, and all off-shell effects are taken into account. The corresponding next-to-leading-order QCD corrections have also been recalculated. All the results are...

Source: http://arxiv.org/abs/1001.2468v1

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Sep 17, 2013
09/13

by
Ansgar Denner; Stefan Dittmaier; Thomas Gehrmann; Christian Kurz

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We present a complete calculation of the electroweak O(alpha^3 alpha_s) corrections to three-jet production and related event-shape observables at electron--positron colliders. The Z-boson resonance is described within the complex-mass scheme, rendering the calculation valid both in the resonance and off-shell regions. Higher-order initial-state radiation is included in the leading-logarithmic approximation. We properly account for the corrections to the total hadronic cross section and for the...

Source: http://arxiv.org/abs/1003.0986v1

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58

Sep 22, 2013
09/13

by
Ansgar Denner; Stefan Dittmaier; Tobias Kasprzik; Alexander Mück

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The first calculation of the next-to-leading-order electroweak corrections to Z-boson + jet hadroproduction including leptonic Z-boson decays is presented, i.e. to the production of a charged lepton--anti-lepton final state in association with one hard jet at the LHC and the Tevatron. The Z-boson resonance is treated consistently using the complex-mass scheme, and all off-shell effects as well as the contributions of the intermediate photon are taken into account. The corresponding...

Source: http://arxiv.org/abs/1103.0914v2

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52

Sep 18, 2013
09/13

by
Ansgar Denner; Stefan Dittmaier; Tobias Kasprzik; Alexander Mück

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Single-jet production with missing transverse momentum is one of the most promising discovery channels for new physics at the LHC. In the Standard Model, Z + jet production with a Z-boson decay into neutrinos leads to this monojet signature. To improve the corresponding Standard Model predictions, we present the calculation of the full next-to-leading-order (NLO) electroweak corrections and a recalculation of the NLO QCD corrections to monojet production at the Tevatron and the LHC. We discuss...

Source: http://arxiv.org/abs/1211.5078v2

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3.0

Jun 28, 2018
06/18

by
Ansgar Denner; Stefan Dittmaier; Markus Hecht; Christian Pasold

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The next-to-leading-order electroweak corrections to $pp\to l^+l^-/\bar\nu\nu+\gamma+X$ production, including all off-shell effects of intermediate Z bosons in the complex-mass scheme, are calculated for LHC energies, revealing the typically expected large corrections of tens of percent in the TeV range. Contributions from quark-photon and photon-photon initial states are taken into account as well, but their impact is found to be moderate or small. Moreover, the known next-to-leading-order QCD...

Topic: High Energy Physics - Phenomenology

Source: http://arxiv.org/abs/1510.08742

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50

Sep 20, 2013
09/13

by
Ansgar Denner; Stefan Dittmaier; Stefan Kallweit; Stefano Pozzorini

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We present details of a calculation of the cross section for hadronic top-antitop production in next-to-leading order (NLO) QCD, including the decays of the top and antitop into bottom quarks and leptons. This calculation is based on matrix elements for \nu e e+ \mu- \bar{\nu}_{\mu}b\bar{b} production and includes all non-resonant diagrams, interferences, and off-shell effects of the top quarks. Such contributions are formally suppressed by the top-quark width and turn out to be small in the...

Source: http://arxiv.org/abs/1207.5018v2

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48

Sep 22, 2013
09/13

by
Ansgar Denner; Stefan Dittmaier; Thomas Gehrmann; Christian Kurz

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We report on a recent calculation of the electroweak O(\alpha^3\alpha_s) corrections to 3-jet production and related event-shape observables at e+e- colliders. The calculation properly accounts for the experimental photon isolation criteria and for the corrections to the total hadronic cross section. Corrections to the normalised event-shape distributions, which are exemplarily discussed here for the thrust distribution at LEP and linear-collider energies, turn out to be at the few-per-cent...

Source: http://arxiv.org/abs/1001.4467v1

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46

Sep 22, 2013
09/13

by
Axel Bredenstein; Ansgar Denner; Stefan Dittmaier; Stefano Pozzorini

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The next-to-leading order (NLO) QCD corrections to top anti-top bottom anti-bottom (tTbB) production at the LHC reveal that the scale choice adopted in previous lowest-order simulations underestimates the tTbB cross section by a factor two. We discuss a new dynamical scale that stabilizes the perturbative predictions and describe the impact of the corrections on the shape of distributions. We also account for the techniques employed to compute the six-particle one-loop amplitudes with high CPU...

Source: http://arxiv.org/abs/1001.4727v1

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54

Sep 22, 2013
09/13

by
Axel Bredenstein; Ansgar Denner; Stefan Dittmaier; Stefano Pozzorini

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We present predictions for top anti-top bottom anti-bottom production at the LHC in next-to-leading order QCD. The precise description of this background process is a prerequisite to observe associated top anti-top Higgs production in the Higgs -> bottom anti-bottom decay channel and to directly measure the top-quark Yukawa coupling at the LHC. The leading-order cross section is extremely sensitive to scale variations. We observe that the traditional scale choice adopted in ATLAS simulations...

Source: http://arxiv.org/abs/1001.4006v1

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73

Sep 23, 2013
09/13

by
Axel Bredenstein; Ansgar Denner; Stefan Dittmaier; Stefano Pozzorini

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We summarise predictions for top anti-top bottom anti-bottom (tTbB) production at the LHC in next-to-leading order QCD. The precise description of this background process is a prerequisite to observe associated top anti-top Higgs production in the H -> bottom anti-bottom decay channel. The one-loop amplitudes are computed using Feynman diagrams and numerical tensor reduction. This approach provides very high numerical stability and CPU efficiency. We find that the scale choice adopted in...

Source: http://arxiv.org/abs/1006.2653v1

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54

Sep 19, 2013
09/13

by
Ansgar Denner; Stefan Dittmaier; Tobias Kasprzik; Alexander Mück

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This talk summarizes the first calculation of the next-to-leading-order electroweak corrections to W-boson + jet hadroproduction including leptonic W-boson decays [1]. The W-boson resonance is treated consistently using the complex-mass scheme, and all off-shell effects are taken into account. The corresponding next-to-leading-order QCD corrections have also been recalculated. All the results are implemented in a flexible Monte Carlo code. Selected numerical results for this Standard Model...

Source: http://arxiv.org/abs/0909.3943v1

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4.0

Jun 30, 2018
06/18

by
Ansgar Denner; Stefan Dittmaier; Markus Hecht; Christian Pasold

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We present a calculation of the next-to-leading-order electroweak corrections to W+\gamma\ production, including the leptonic decay of the W boson and taking into account all off-shell effects of the W boson, where the finite width of the W boson is implemented using the complex-mass scheme. Corrections induced by incoming photons are fully included and find particular emphasis in the discussion of phenomenological predictions for the LHC. The corresponding next-to-leading-order QCD corrections...

Topic: High Energy Physics - Phenomenology

Source: http://arxiv.org/abs/1412.7421

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3.0

Jun 30, 2018
06/18

by
Ansgar Denner; Stefan Dittmaier; Stefan Kallweit; Alexander Mück

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The Monte Carlo integrator HAWK provides precision predictions for Higgs production at hadron colliders in vector-boson fusion and Higgs strahlung, i.e. in production processes where the Higgs boson is Attached to WeaK bosons. The fully differential predictions include the full QCD and electroweak next-to-leading-order corrections. Results are computed as integrated cross sections and as binned distributions for important hadron-collider observables.

Topics: High Energy Physics - Phenomenology, High Energy Physics - Experiment

Source: http://arxiv.org/abs/1412.5390

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41

Sep 23, 2013
09/13

by
Ansgar Denner; Stefan Dittmaier; Stefan Kallweit; Alexander Muck

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We briefly report on the inclusion of NLO QCD and electroweak corrections to the Higgs-strahlung processes pp/ppbar -> HW/Z -> H+2leptons in the Monte Carlo program HAWK. The electroweak corrections, which are at the level of -(5-10)% for total cross sections, further increase in size with increasing transverse momenta (p_T) in differential cross sections. For instance, for p_{T,H}>200GeV, which is the interesting range at the LHC, the electroweak corrections to WH production reach...

Source: http://arxiv.org/abs/1112.5258v1

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42

Sep 22, 2013
09/13

by
Ansgar Denner; Stefan Dittmaier; Thomas Gehrmann; Christian Kurz

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We compute the electroweak ${\cal O}(\alpha^3\alpha_s)$ corrections to three-jet production and related event-shape observables at electron-positron colliders. We properly account for the experimental photon isolation criteria and for the corrections to the total hadronic cross section. Corrections to the three-jet rate and to normalised event-shape distributions turn out to be at the few-per-cent level.

Source: http://arxiv.org/abs/0906.0372v2

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4.0

Jun 29, 2018
06/18

by
Ansgar Denner; Laura Jenniches; Jean-Nicolas Lang; Christian Sturm

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We present a consistent renormalization scheme for the CP-conserving Two-Higgs-Doublet Model based on $\overline{MS}$ renormalization of the mixing angles and the soft-$Z_2$-symmetry-breaking scale $M_{sb}$ in the Higgs sector. This scheme requires to treat tadpoles fully consistently in all steps of the calculation in order to provide gauge-independent $S$-matrix elements. We show how bare physical parameters have to be defined and verify the gauge independence of physical quantities by...

Topic: High Energy Physics - Phenomenology

Source: http://arxiv.org/abs/1607.07352

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5.0

Jun 29, 2018
06/18

by
Ansgar Denner; Jean-Nicolas Lang; Mathieu Pellen; Sandro Uccirati

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We present NLO electroweak corrections to Higgs production in association with off-shell top-antitop quark pairs. The full process $\text{p}\text{p}\to\text{e}^+\nu_{\text{e}} \mu^-\bar{\nu}_\mu\text{b}\bar{\text{b}} \text{H}$ is considered, and hence all interference, off-shell, and non-resonant contributions are taken into account. The electroweak corrections turn out to be below one per cent for the integrated cross section but can exceed $10\%$ in certain phase-space regions. In addition to...

Topics: High Energy Physics - Phenomenology, High Energy Physics - Experiment

Source: http://arxiv.org/abs/1612.07138

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3.0

Jun 29, 2018
06/18

by
Benedikt Biedermann; Ansgar Denner; Stefan Dittmaier; Lars Hofer; Barbara Jager

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We present a state-of-the-art calculation of the next-to-leading-order electroweak corrections to ZZ production, including the leptonic decays of the Z bosons into $\mu^+\mu^-\mathrm{e}^+\mathrm{e}^-$ or $\mu^+\mu^-\mu^+\mu^-$ final states. We use complete leading-order and next-to-leading-order matrix elements for four-lepton production, including contributions of virtual photons and all off-shell effects of Z bosons, where the finite Z-boson width is taken into account using the complex-mass...

Topics: High Energy Physics - Phenomenology, High Energy Physics - Experiment

Source: http://arxiv.org/abs/1611.05338

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Sep 18, 2013
09/13

by
Stefano Actis; Ansgar Denner; Lars Hofer; Andreas Scharf; Sandro Uccirati

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We introduce the computer code Recola for the recursive generation of tree-level and one-loop amplitudes in the Standard Model. Tree-level amplitudes are constructed using off-shell currents instead of Feynman diagrams as basic building blocks. One-loop amplitudes are represented as linear combinations of tensor integrals whose coefficients are calculated similarly to the tree-level amplitudes by recursive construction of loop off-shell currents. We introduce a novel algorithm for the treatment...

Source: http://arxiv.org/abs/1211.6316v2

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5.0

Jun 29, 2018
06/18

by
Stefano Actis; Ansgar Denner; Lars Hofer; Jean-Nicolas Lang; Andreas Scharf; Sandro Uccirati

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We present the Fortran95 program Recola for the perturbative computation of next-to-leading-order transition amplitudes in the Standard Model of particle physics. The code provides numerical results in the 't Hooft-Feynman gauge. It uses the complex-mass scheme and allows for a consistent isolation of resonant contributions. Dimensional regularization is employed for ultraviolet and infrared singularities, with the alternative possibility of treating collinear and soft singularities in mass...

Topic: High Energy Physics - Phenomenology

Source: http://arxiv.org/abs/1605.01090

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Jun 29, 2018
06/18

by
Benedikt Biedermann; Marina Billoni; Ansgar Denner; Stefan Dittmaier; Lars Hofer; Barbara Jager; Lukas Salfelder

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We present results of the first calculation of next-to-leading-order electroweak corrections to W-boson pair production at the LHC that fully takes into account leptonic W-boson decays and off-shell effects. Employing realistic event selections, we discuss the corrections in situations that are typical for the study of W-boson pairs as a signal process or of Higgs-boson decays $H\to W W^*$, to which W-boson pair production represents an irreducible background. In particular, we compare the full...

Topics: High Energy Physics - Phenomenology, High Energy Physics - Experiment

Source: http://arxiv.org/abs/1605.03419

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Sep 20, 2013
09/13

by
Ernestos N. Argyres; Wim Beenakker; Ansgar Denner; Stefan Dittmaier; Jiri Hoogland; Ronald Kleiss; Geert Jan van Oldenborgh; Costas G. Papadopoulos; Giampiero Passarino

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We discuss theoretical and phenomenological aspects of the use of boson propagators with energy-dependent widths in predictions for high-energy scattering processes. In general, gauge invariance is violated in such calculations. We discuss several approaches to restore gauge invariance, necessary for a reliable result. The most promising method is the addition of the relevant parts of the fermionic corrections, which fulfills all Ward identities. The numerical difference between this and other...

Source: http://arxiv.org/abs/hep-ph/9507216v2