α s from the updated ALEPH data for hadronic τ decays

Boito, Diogo; Golterman, Maarten; Maltman, Kim; Osborne, James; Peris, Santiago

doi:10.1016/j.nuclphysbps.2016.02.022

Cited by 18 publications

(71 citation statements)

References 70 publications

(290 reference statements)

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“…The value of α s , together with the mass of the top quark, plays, for example, a crucial role in the fate of the Standard Model vacuum [1]. The extraction of α s from hadronic τ decays [2][3][4][5] (and also from e + e − → (hadrons) below charm [6,7]) is of special interest for two reasons. First, because it is done at relatively low energies, close to the limit of validity of perturbative QCD.…”

Section: Introductionmentioning

confidence: 99%

“…At and around the τ mass, perturbative QCD is still valid, but non-perturbative effects become non-negligible. These effects are smaller by a factor of about ten when compared to the perturbative QCD contribution, but must be taken into account carefully [3,13]. They are encoded in the condensates of the Operator Product Expansion (OPE) and the related contributions from violations of quark-hadron duality -or simply duality violations (DVs) [14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Higher-order QCD corrections to hadronic τ decays from Padé approximants

Boito

Masjuan

Oliani

2018

J. High Energ. Phys.

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105

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Perturbative QCD corrections to hadronic τ decays and e + e − annihilation into hadrons below charm are obtained from the Adler function, which at present is known in the chiral limit to five-loop accuracy. Extractions of the strong coupling, α s , from these processes suffer from an ambiguity related to the treatment of unknown higher orders in the perturbative series. In this work, we exploit the method of Padé approximants and its convergence theorems to extract information about higher-order corrections to the Adler function in a systematic way. First, the method is tested in the large-β 0 limit of QCD, where the perturbative series is known to all orders. We devise strategies to accelerate the convergence of the method employing renormalization scheme variations and the so-called D-log Padé approximants. The success of these strategies can be understood in terms of the analytic structure of the series in the Borel plane. We then apply the method to full QCD and obtain reliable model-independent predictions for the higher-order coefficients of the Adler function. For the six-, seven-, and eight-loop coefficients we find c 5,1 = 277 ± 51, c 6,1 = 3460±690, and c 7,1 = (2.02±0.72)×10 4 , respectively, with errors to be understood as lower and upper bounds. Our model-independent reconstruction of the perturbative QCD corrections to the τ hadronic width strongly favours the use of fixed-order perturbation theory (FOPT) for the renormalization-scale setting.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Higher-order QCD corrections to hadronic τ decays from Padé approximants

Boito

Masjuan

Oliani

2018

J. High Energ. Phys.

Self Cite

105

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“…Slightly smaller (10%) values of α s (m τ ) have been obtained in Ref. [33] through a direct fit of the vector spectral function from s =ŝ 0 = 1.55 GeV 2 to m 2 τ , with a 4-parameter ansatz for ρ V (s), plus the moment A ω=1 V (ŝ 0 ). This approach maximizes the role of non-perturbative effects in order to better study them [34,35], but this is not a good strategy to perform an accurate determination of the strong coupling.…”

Section: Inclusive Observables (A Pich)mentioning

confidence: 99%

Determining the strong coupling - status and challenges

Pich¹,

Rojo²,

Sommer³

et al. 2019

Proceedings of XIII Quark Confinement and the Hadron Spectrum — PoS(Confinement2018)

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The "XIIIth Quark Confinement and the Hadron Spectrum" conference (Confinement 2018) contained a "Round Table Discussion" on the status of the determinations of the strong coupling α s (m Z ) as well as prospects for future improvements. In this contribution, we summarize the different aspects of the discussion. In particular, we cover α s determinations from inclusive observables, such as the hadronic decays of the Z boson and the τ lepton; from global fits of parton distribution functions (PDFs); from high-energy collider observables, and from event shapes; as well as from various observables computed by lattice QCD, specifically from the QCD static energy. There is overall good agreement between these various determinations, but there are also outliers, differing from the world average by up to −5%. Nevertheless, the general agreement constitutes a beautiful and significant test of the detailed nature of the strong interactions, and provides a crucial input for high-precision calculations in QCD and beyond.

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“…This together with the limited precision of the OPAL data explained larger uncertainties on these α s determinations. 1 1 During the workshop, another determination based on the same method was reported using the new spectral functions of ALEPH [5], details of the analysis are available after the workshop in [27]. In this article, it was claimed that the original method proposed in [1], neglecting the nonperturbative contribution at orders higher than D = …”

Section: Measurements Of α S (Mmentioning

confidence: 99%

Tau Decays and αs

Zhang

2015

Nuclear and Particle Physics Proceedings

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The evolution of the determination of the strong coupling constant α s from the leptonic branching ratios, the lifetime, and the invariant mass distributions of the hadronic final state of the τ lepton over the last two decades is briefly reviewed. The improvements in the latest ALEPH update are described in some detail. Currently this is one of the most precise α s determinations. Together with the other determination at the Z boson mass pole, they constitutes the most accurate test of the asymptotic freedom in QCD.

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α s from the updated ALEPH data for hadronic τ decays

Cited by 18 publications

References 70 publications

Higher-order QCD corrections to hadronic τ decays from Padé approximants

Higher-order QCD corrections to hadronic τ decays from Padé approximants

Determining the strong coupling - status and challenges

Tau Decays and αs

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