Electroweak corrections on the toponium resonance

Grza̧dkowski, Bohdan; Kühn, Johann H.; Krawczyk, P.; Stuart, Robin G.

doi:10.1016/0550-3213(87)90245-8

Cited by 65 publications

(65 citation statements)

References 10 publications

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“…(The full result including the energy dependence, can be found in [57,60].) Indeed the difference of 5% between the heavy and the light Higgs boson is well consistent with this simple approximation.…”

Section: The Top-pair Threshold Region and The Yukawa Couplingsupporting

confidence: 58%

Weak interactions in top-quark pair production at hadron colliders: An Update

Kühn¹,

Uwer²

2016

Proceedings of 12th International Symposium on Radiative Corrections (Radcor 2015) and LoopFest XIV (Radiative Corrections for

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Weak corrections for top-quark pair production at hadron colliders are revisited. Predictions for collider energies of 8 TeV, adopted to the recent LHC run, and for 13 as well as 14 TeV, presumably relevant for the next round of LHC experiments, are presented. Kinematic regions with large momentum transfer are identified, where the corrections become large and may lead to strong distortions of differential distributions, thus mimicking anomalous top quark couplings. As a complementary case we investigate the threshold region, corresponding to configurations with small relative velocity between top and antitop quark, which is particularly sensitive to the top-quark Yukawa coupling. We demonstrate, that nontrivial upper limits on this coupling, complementary to those recently derived by the CMS and the ATLAS collaorations, are well within reach of ongoing experiments. We, furthermore, suggest a prescription that allows the implementation of these corrections in current Monte Carlo generators. Furthermore, the weak corrections are have been included in the publicly available Hathor library. The numerical results presented in this article use the same setup as the recently calculated NNLO QCD corrections. The results can thus be combined to give the most precise theoretical predictions.1

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Section: The Top-pair Threshold Region and The Yukawa Couplingsupporting

confidence: 58%

Weak interactions in top-quark pair production at hadron colliders: An Update

Kühn¹,

Uwer²

2016

Proceedings of 12th International Symposium on Radiative Corrections (Radcor 2015) and LoopFest XIV (Radiative Corrections for

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“…Prior to numerical evaluation of these functions, we prefer the above expressions both because of their conciseness and because they explicitly demonstrate the vanishing of Φ and Λ as q 2 → 0. In the limit m F → 0, we verify that both Φ and Λ reduce to the well known expressions for the vertex in the massless limit [8,18,22].…”

Section: New Gauge Bosonssupporting

confidence: 68%

The effect of new physics on

Liu¹,

Ng²

1995

Physics Letters B

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Motivated by the ∼ 2σ discrepancy between the experimental value for R b and the theoretical prediction of the Standard Model, we examine the effect of new physics on the Z-b-b vertex. Using general results for both new scalars and gauge bosons, we show that two conditions must be satisfied in order for new physics to give observable deviations in the vertex. In particular, the fermion in the loop must transform chirally under SU (2) × U (1) and it must be massive compared to the exchanged boson. We examine the implications of these results on the 2 Higgs Doublet model and the Left-Right Symmetric model.

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“…[22] (see also Refs. [23,24]). The imaginary terms with C int V=A;1 contain finite lifetime effects arising from the interference of the dominant double-resonant process e þ e À !…”

Section: B Top-pair Production Currentsmentioning

confidence: 97%

“…The divergences are absorbed by the counterterms associated to the ðe þ e À Þðe þ e À Þ forward scattering operatorsÕ V=A given in Eq. (24) and are treated with the usual renormalization techniques known from effective theories. However, it is a novel feature that the phase space divergences and the anomalous dimension of the operators O V=A are purely imaginary.…”

Section: E Phase Space Divergences and Renormalization Group Evolutionmentioning

confidence: 99%

Phase space matching and finite lifetime effects for top-pair production close to threshold

2010

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The top-pair t " t production cross section close to threshold in e þ e À collisions is strongly affected by the small lifetime of the top quark. Since the cross section is defined through final states containing the top decay products, a consistent definition of the cross section depends on prescriptions of how these final states are accounted for the cross section. Experimentally, these prescriptions are implemented, for example, through cuts on kinematic quantities such as the reconstructed top quark invariant masses. As long as these cuts do not reject final states that can arise from the decay of a top and an antitop quark with a small off-shellness compatible with the nonrelativistic power counting, they can be implemented through imaginary phase space matching conditions in nonrelativistic QCD. The prescription-dependent cross section can then be determined from the optical theorem using the e þ e À forward scattering amplitude. We compute the phase space matching conditions associated to cuts on the top and antitop invariant masses at next-to-next-to-leading logarithmic order and partially at next-to-next-to-next-toleading logarithmic order in the nonrelativistic expansion accounting also for higher order QCD effects. Together with finite lifetime and electroweak effects known from previous work, we analyze their numerical impact on the t " t cross section. We show that the phase space matching contributions are essential to make reliable nonrelativistic QCD predictions, particularly for energies below the peak region, where the cross section is small. We find that irreducible background contributions associated to final states that do not come from top decays are strongly suppressed and can be neglected for the theoretical predictions.

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Electroweak corrections on the toponium resonance

Cited by 65 publications

References 10 publications

Weak interactions in top-quark pair production at hadron colliders: An Update

Weak interactions in top-quark pair production at hadron colliders: An Update

The effect of new physics on

Phase space matching and finite lifetime effects for top-pair production close to threshold

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