Electroweak non-resonant NLO corrections to in the resonance region

Beneke, Μ.; Jantzen, Bernd; Ruiz-Femenía, Pedro

doi:10.1016/j.nuclphysb.2010.07.006

Cited by 42 publications

(107 citation statements)

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“…The bands show the result of varying µ soft in the interval 15-60 GeV. For comparison, the NLO non-resonant contribution (dotted black line), σ (1) non−res from [7], is also shown.…”

Section: Resultsmentioning

confidence: 99%

“…The separation of resonant and nonresonant effects can be achieved systematically by expanding the full electroweak theory diagrams of the e + e − forwardscattering amplitude according to regions with small (p 2 t − m 2 t ∼ m t Γ t ) and large (p 2 t − m 2 t ∼ m 2 t ) virtuality in the top and antitop lines [7,12]. The leading nonresonant contributions are given by two-loop diagrams of order α 3 EW with 3-particle cuts bW +t and bW − t, and are suppressed by α EW /v ∼ v (NLO) with respect the leading order (resonant) cross section.…”

Section: Nnlo Nonresonant Cross Sectionmentioning

confidence: 99%

“…2. Taking into account that its endpoint behaviour is (Λ/m t ) 3 ∼ (1 − x) 3/2 [7], an overall scaling (1 − x) −1/2 ρ −1/2 is then found for diagram h 5a , in agreement with the findings of [1]. Diagram h 10a carries a further (1 − x) 2 suppression factor because s-channel W + W − production is suppressed in the non-relativistic limit.…”

Section: Nnlo Nonresonant Cross Sectionmentioning

confidence: 99%

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First estimate of the NNLO nonresonant corrections to top-antitop threshold production at lepton colliders

Ruiz-Femenía

2014

Phys. Rev. D

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We compute the dominant term in the expansion in ρ = 1 − MW /mt of the unknown next-to-next-to-leading order (NNLO) nonresonant contributions to the e + e − → W + W − bb total cross section at energies close to the top-antitop threshold. Our analytic result disagrees with a previous calculation by other authors [1]. We show that our determination has the correct infrared structure needed to cancel the divergences proportional to the top width arising in the resonant production of the same final state, and we point out to a missing contribution in the computation of [1] to explain the discrepancy.

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“…The bands show the result of varying µ soft in the interval 15-60 GeV. For comparison, the NLO non-resonant contribution (dotted black line), σ (1) non−res from [7], is also shown.…”

Section: Resultsmentioning

confidence: 99%

Section: Nnlo Nonresonant Cross Sectionmentioning

confidence: 99%

Section: Nnlo Nonresonant Cross Sectionmentioning

confidence: 99%

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First estimate of the NNLO nonresonant corrections to top-antitop threshold production at lepton colliders

Ruiz-Femenía

2014

Phys. Rev. D

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“…Consistent inclusion of all effects related to the instability of the top quark is needed. Some recent progress in this direction has been made [262][263][264]. It is expected that a linear collider will provide an m t determination with uncertainties at the level of 100 MeV (see Sect.…”

Section: Mt Determinationmentioning

confidence: 99%

Heavy quarkonium: progress, puzzles, and opportunities

Brambilla¹,

Eidelman²,

Heltsley³

et al. 2011

Advances in the Physics of Particles and Nuclei

103

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A golden age for heavy quarkonium physics dawned a decade ago, initiated by the confluence of exciting advances in quantum chromodynamics (QCD) and an explosion of related experimental activity. The early years of this period were chronicled in the Quarkonium Working Group (QWG) CERN Yellow Report (YR) in 2004, which presented a comprehensive review of the status of the field at that time and provided specific recommendations for further progress. However, the broad spectrum of subsequent breakthroughs, surprises, and continuing puzzles could only be partially anticipated. Since the release of the YR, the BESII program concluded only to give birth to BESIII; the B-factories and CLEO-c flourished; quarkonium production and polarization measurements at HERA and the Tevatron matured; and heavy-ion collisions at RHIC have opened a window on the deconfinement regime. All these experiments leave legacies of quality, precision, and unsolved mysteries for quarkonium physics, and therefore beg for continuing investigations at BESIII, the LHC, RHIC, FAIR, the Super Flavor and/or Tau-Charm factories, JLab, the ILC, and beyond. The list of newly-found conventional states expanded to include hc(1P ), χc2(2P ), B + c , and η b (1S). In addition, the unexpected and still-fascinating X(3872) has been joined by * Editors † Section coordinators ‡ Corresponding author: bkh2@cornell.edu more than a dozen other charmonium-and bottomonium-like "XY Z" states that appear to lie outside the quark model. Many of these still need experimental confirmation. The plethora of new states unleashed a flood of theoretical investigations into new forms of matter such as quark-gluon hybrids, mesonic molecules, and tetraquarks. Measurements of the spectroscopy, decays, production, and in-medium behavior of cc, bb, and bc bound states have been shown to validate some theoretical approaches to QCD and highlight lack of quantitative success for others. Lattice QCD has grown from a tool with computational possibilities to an industrialstrength effort now dependent more on insight and innovation than pure computational power. New effective field theories for the description of quarkonium in different regimes have been developed and brought to a high degree of sophistication, thus enabling precise and solid theoretical predictions. Many expected decays and transitions have either been measured with precision or for the first time, but the confusing patterns of decays, both above and below open-flavor thresholds, endure and have deepened. The intriguing details of quarkonium suppression in heavy-ion collisions that have emerged from RHIC have elevated the importance of separating hotand cold-nuclear-matter effects in quark-gluon plasma studies. This review systematically addresses all these matters and concludes by prioritizing directions for ongoing and future efforts.

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“…For the same reason, it will be mandatory to consider the process e + e − → W + W − bb including the non-resonant contributions. Non-resonant effects have been computed to NLO and partially to NNLO accuracy [33][34][35][36], and can be naturally separated in the framework of unstable particle EFT [37,38]. d) Electromagnetic initial-state radiation generates large logarithms ln(4m 2 t /m 2 e ), where m e is the electron mass, which must be summed.…”

mentioning

confidence: 99%

Next-to-Next-to-Next-to-Leading Order QCD Prediction for the Top AntitopS-Wave Pair Production Cross Section Near Threshold ine+e−Annihilation

et al. 2015

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We present the third-order QCD prediction for the production of top-anti-top quark pairs in electronpositron collisions close to the threshold in the dominant S-wave state. We observe a significant reduction of the theoretical uncertainty and discuss the sensitivity to the top quark mass and width.PACS numbers: 14.65. Ha, 12.38.Bx, 13.66.Bc Among the main motivations for building a future highenergy electron-positron collider in steps of increasing center-of-mass energy are precise measurements at √ s ≈ 345 GeV close to the production threshold of top antitop quark pairs. The peculiar behaviour of the cross section allows for the precise determination of a number of Standard Model parameters, most prominently the top quark mass. To date the most precise measurement of m t = 173.34±0.27(stat)±0.71(syst) GeV comes from the hadron colliders Fermilab Tevatron and CERN LHC [1] and is based on the reconstruction of the top and antitop quarks through their decay products. This approach and the value quoted above are plagued by unknown relations of the extracted mass value m t to top quark masses in the pole or MS renormalization scheme, which may well exceed 1 GeV. At hadron colliders there are also methods to determine directly a well-defined top quark mass, such as the extraction of m t from top quark cross section measurements. However, the final precision is of the order of a few GeV and thus significantly worse. At an electron-positron collider, on the other hand, scans of the top anti-top pair production threshold can lead to very precise measurements of well-defined mass values with a statistical accuracy of only 20-30 MeV [2,3]. Besides the top quark mass also its decay width and the strong coupling constant can be extracted with an accuracy of 21 MeV [3] and 0.0009 [2], respectively. A recent study has shown that for a Higgs boson with a mass of about 125 GeV the top quark Yukawa coupling can be obtained with a statistical uncertainty of only 4.2% [3]. These numbers pose several challenges to theory.A crucial input to reach the aimed precision is a precise calculation of the top anti-top pair production cross section in the threshold region. While the fundamental theory of quantum chromodyanmics (QCD) is wellestablished, performing calculations of quantum corrections to the very high accuracies demanded here is very difficult indeed. The problem is further complicated by the fact that in the threshold region the colour Coulomb potential ∝ α s /r, where α s denotes the strong coupling, can no longer be treated as a perturbation even though α s ≪ 1. Standard perturbation theory in α s breaks down and resummation is required.The relevant techniques have been developed in the 1990s in the framework of effective field theory (EFT), which accounts for the different dynamical scales in the problem. For a heavy quark anti-quark system at threshold there are three relevant scales, the hard scale m, the potential and soft scale mv, and the ultrasoft scale mv 2 , where m denotes the mass of the quark and v its velocit...

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Electroweak non-resonant NLO corrections to in the resonance region

Cited by 42 publications

References 58 publications

First estimate of the NNLO nonresonant corrections to top-antitop threshold production at lepton colliders

First estimate of the NNLO nonresonant corrections to top-antitop threshold production at lepton colliders

Heavy quarkonium: progress, puzzles, and opportunities

Next-to-Next-to-Next-to-Leading Order QCD Prediction for the Top AntitopS-Wave Pair Production Cross Section Near Threshold ine+e−Annihilation

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