How suppressed are the radiative interference effects in heavy unstable particle production?

Fadin, V.S.; Хозе, В. А.; Martin, A. D.

doi:10.1016/0370-2693(94)90837-0

Cited by 89 publications

(82 citation statements)

References 6 publications

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“…We have chosen this rather unusual representation for the energy parameter since it greatly simplifies, because of its symmetric form in Eq. (19), the analytic matching calculations we carry out in App. A.…”

Section: The Conceptual Framework -Nrqcd and Pnrqcdmentioning

confidence: 99%

“…(12) and (13), are directly related to the Green functioñ G(k, k ′ ; q 2 ) of the Schrödinger equation (19), which describes off-shell elastic scattering of a topantitop pair with centre-of-mass three momentum ±k into a top-antitop pair with three momentum ±k ′ . We emphasize that the Green function does not describe the scattering of on-shell top quarks because the common three-dimensional formulation in the form of the Schrödinger equation (19) already contains an implicit integration over the zero-components of the momenta in the heavy quark propagators. Because the heavy quark potential is energy-independent this integration is trivial by residues.…”

Section: Lippmann-schwinger Equationmentioning

confidence: 99%

“…Interconnection effects caused by gluon exchange among top-antitop decay and production processes are not considered in this work. They are known to vanish at NLO for the total cross section [18,19,20], but can lead to sizeable corrections in the momentum distribution [21,22]. We also include the total cross section and the three-momentum distribution induced by the axial-vector current.…”

Section: Introductionmentioning

confidence: 99%

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Top-quark pair production close to threshold: Top-quark mass, width, and momentum distribution

1999

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The complete NNLO QCD corrections to the total cross section σ(e + e − → Z * , γ * → tt), in the kinematic region close to the top-antitop threshold, are calculated by solving the corresponding Schrödinger equations exactly in momentum space in a consistent momentum cutoff regularization scheme. The corrections coming from the same NNLO QCD effects to the top quark three-momentum distribution dσ/d| k t | are determined. We discuss the origin of the large NNLO corrections to the peak position and the normalization of the total cross section observed in previous works and propose a new top mass definition, the 1S mass M 1S , which stabilizes the peak in the total cross section. If the influence of beamstrahlung and initial state radiation on the mass determination is small, a theoretical uncertainty on the 1S top mass measurement of 200 MeV from the total cross section at the linear collider seems possible. We discuss how well the 1S mass can be related to the MS mass. We propose a consistent way to implement the top quark width at NNLO by including electroweak effects into the NRQCD matching coefficients, which can then become complex.

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Section: The Conceptual Framework -Nrqcd and Pnrqcdmentioning

confidence: 99%

Section: Lippmann-schwinger Equationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Top-quark pair production close to threshold: Top-quark mass, width, and momentum distribution

1999

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“…We neglect interference between radiation in the two stages, which are expected to be small, [24][25][26]. This whole procedure can be illustrated as follows:…”

Section: Analytical Resultsmentioning

confidence: 99%

Constraints on Randall-Sundrum model from the events of dijet production with QCD next-to-leading order accuracy at the LHC

et al. 2015

Phys. Rev. D

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We study the dijet production in Randall-Sundrum model at the LHC with QCD next-toleading(NLO) order accuracy. Our results show that the QCD NLO corrections can increase the total cross sections by more than 80% and reduce the scale dependence. We also explore in detail several important kinematic distributions at the NLO level. Moreover, we discuss the upper limits of the KK graviton excluded mass range and the allowed parameter space for the coupling constant and KK graviton mass, using the experiment data.

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“…Let us also stress that the axial 2 rate, although closely related to the S − P wave interference piece, is an independent observable. Rescattering corrections, which are present in the angular distribution and in the top polarization, are calculated to O(α s ) [11,12] but shown to be unimportant as long as the total cross section is concerned [17,18]. In addition, rescattering corrections do not affect the separation between axial and vector contributions.…”

Section: Introductionmentioning

confidence: 94%

Axial contributions at the top threshold

Kühn

Teubner

1999

Eur. Phys. J. C

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We calculate the contributions of the axial current to top quark pair production in e + e − annihilation at threshold. The QCD dynamics is taken into account by solving the Lippmann-Schwinger equation for the P wave production using the QCD potential up to two loops. We demonstrate that the dependence of the total and differential cross section on the polarization of the e + and e − beams allows for an independent extraction of the axial current induced cross section.Top quark production at an electron-positron collider [1] has been demonstrated to be ideally suited for a precise determination of the top quark mass and for the study of its couplings in production and decay. Due to its rapid decay large distance nonperturbative QCD effects are irrelevant for the description of the top quark [2], and the tt system is well described by perturbative QCD [3]. It allows to explore the interquark potential at small distances, which is closely related to the strong coupling constant. One might eventually even become sensitive to the t-t-Higgs coupling through virtual corrections. In order to constrain this multitude of parameters in an optimal * The complete postscript file of this preprint, including figures, is available via anonymous ftp at www-ttp.physik.uni-karlsruhe. de (129.13.102.139) as /ttp99-12/ttp99-12.ps or via www at http://www-ttp.physik.uni-karlsruhe.de/cgi-bin/preprints. way and to reduce inevitable theoretical uncertainties, it is desirable to measure a large variety of different observables. Originally the main emphasis had been put on the total cross section [3,4]. The excitation curve with its steep rise (the remnant of the 1S toponium resonance) is ideally suited for the measurement of the top quark mass m t . The correlation between m t and the strength of the potential (α s ) can be reduced by comparing data and predictions for the momentum distribution of the top quarks [5,6,7,8], which reflects essentially their Fermi motion in the bound state and the smearing of the momentum due to the large decay rate Γ t , a consequence of the uncertainty principle. All these quantities were calculated for the S wave amplitude, which is induced by both the electromagnetic current and the vector part of the neutral current close to threshold. Expanding in the limit of small velocities β = 1 − 4m 2 t /s ( √ s being the total centre of mass energy), the next term is due to S − P wave interference. The subleading P wave amplitude originates from the production through the axial vector current. The interference term is responsible for the anisotropic angular dependence, specifically the term linear in cos θ, and the resulting forward-backward asymmetry [9]. Similarly, an angular dependent polarization of top quarks is induced by the S − P wave interference which adds to the dominant polarization parallel to the e + e − beams [10]. Rescattering corrections [11,12], although important for the detailed quantitative analysis, do not alter this qualitative picture.Clearly, the next step in this sequence of im...

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How suppressed are the radiative interference effects in heavy unstable particle production?

Cited by 89 publications

References 6 publications

Top-quark pair production close to threshold: Top-quark mass, width, and momentum distribution

Top-quark pair production close to threshold: Top-quark mass, width, and momentum distribution

Constraints on Randall-Sundrum model from the events of dijet production with QCD next-to-leading order accuracy at the LHC

Axial contributions at the top threshold

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