Strong coupling from an improved 
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 vector isovector spectral function

Boito, Diogo; Golterman, Maarten; Maltman, Kim; Peris, Santiago; Rodrigues, Marcus V.; Schaaf, Wilder

doi:10.1103/physrevd.103.034028

Cited by 31 publications

(30 citation statements)

References 87 publications

(103 reference statements)

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“…either by multiplication of the proper Γ (n) factors or by using the inverse Borel integral in Eq. (11). Likewise the form of Eq.…”

Section: Theory Input For the τ Spectral Function Momentsmentioning

confidence: 95%

“…(12) in the entire complex u-plane can be uniquely determined from summing the absolute convergent Taylor series (13) within its radius of convergence (which is 1 due to the p = −1 poles) and using analytic continuation. The poles for negative p are the so-called UV renormalons and are related to signalternating divergence patterns which can be formally summed in the Borel representation (11). In QCD the UV renormalons arise from the large-momentum behavior of the loop diagrams.…”

Section: Theory Input For the τ Spectral Function Momentsmentioning

confidence: 99%

“…(1). Using the 5-loop results [3][4][5] an impressive precision of about 5% has been achieved for α s (m 2 τ ) (corresponding to an uncertainty of 1.5% for α s (m 2 Z )), where the uncertainty is dominated by the perturbative error in δ (0) W (s 0 ) [8,9,11,12]. A major limitation of α s determinations from the moments A W (s 0 ) arises from the fact that two different expansion approaches to evaluate δ (0) W (s 0 ), called contour-improved perturbation theory (CIPT) and fixedorder perturbation theory (FOPT) yield systematic numerical differences that do not seem to be covered by the conventional perturbative uncertainty estimates related to renormalization scale variations.…”

Section: Introductionmentioning

confidence: 99%

“…( 1 ). Using the 5-loop results [ 3 – 5 ] an impressive precision of about has been achieved for (corresponding to an uncertainty of for ), where the uncertainty is dominated by the perturbative error in [ 8 , 9 , 11 , 12 ].…”

Section: Introductionmentioning

confidence: 99%

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On the difference between FOPT and CIPT for hadronic tau decays

Hoang

Regner

2021

Eur. Phys. J. Spec. Top.

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In this article we review the results of our recent work on the difference between the Borel representations of $$\tau $$ τ hadronic spectral function moments obtained with the CIPT and FOPT methods. For the presentation of the theoretical results we focus on the large-$$\beta _0$$ β 0 approximation, where all expressions can be written down in closed form, and we comment on the generalization to full QCD. The results may explain the discrepancy in the behavior of the FOPT and CIPT series that has been the topic of intense discussions in previous literature and which represents a major part of the theoretical uncertainties in current strong coupling determinations from hadronic $$\tau $$ τ decays. The findings also imply that the OPE corrections for FOPT and CIPT differ and that the OPE corrections for CIPT do not have standard form.

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“…either by multiplication of the proper Γ (n) factors or by using the inverse Borel integral in Eq. (11). Likewise the form of Eq.…”

Section: Theory Input For the τ Spectral Function Momentsmentioning

confidence: 95%

Section: Theory Input For the τ Spectral Function Momentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

On the difference between FOPT and CIPT for hadronic tau decays

Hoang

Regner

2021

Eur. Phys. J. Spec. Top.

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“…In a recent work [99], the mentioned DV-model strategy was used in FOPT-evaluated FESRs of semihadronic τ -decays, using an experimental spectral V-channel function based on data from various experiments (ALEPH, OPAL, BABAR, and supplemented by e + e − → hadrons data), and they obtained the result α s (m 2 τ ) = 0.3077 ± 0.0075, which is very close to our result α s (m 2 τ ) = 0.3075 +0.0066 −0.0069 obtained from Borel-Laplace sum rule global fit with FOPT method, cf. Eq.…”

Section: Summary Of the Results And Comparison With Literaturementioning

confidence: 95%

Determination of perturbative QCD coupling from ALEPH $$\tau $$ decay data using pinched Borel–Laplace and Finite Energy Sum Rules

2021

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We present a determination of the perturbative QCD (pQCD) coupling using the V+A channel ALEPH $$\tau $$ τ -decay data. The determination involves the double-pinched Borel–Laplace Sum Rules and Finite Energy Sum Rules. The theoretical basis is the Operator Product Expansion (OPE) of the V+A channel Adler function in which the higher order terms of the leading-twist part originate from a model based on the known structure of the leading renormalons of this quantity. The applied evaluation methods are contour-improved perturbation theory (CIPT), fixed-order perturbation theory (FOPT), and Principal Value of the Borel resummation (PV). All the methods involve truncations in the order of the coupling. In contrast to the truncated CIPT method, the truncated FOPT and PV methods account correctly for the suppression of various renormalon contributions of the Adler function in the mentioned sum rules. The extracted value of the $${\overline{\mathrm{MS}}}$$ MS ¯ coupling is $$\alpha _s(m_{\tau }^2) = 0.3116 \pm 0.0073$$ α s ( m τ 2 ) = 0.3116 ± 0.0073 [$$\alpha _s(M_Z^2)=0.1176 \pm 0.0010$$ α s ( M Z 2 ) = 0.1176 ± 0.0010 ] for the average of the FOPT and PV methods, which we regard as our main result. On the other hand, if we include in the average also the CIPT method, the resulting values are significantly higher, $$\alpha _s(m_{\tau }^2) = 0.3194 \pm 0.0167$$ α s ( m τ 2 ) = 0.3194 ± 0.0167 [$$\alpha _s(M_Z^2)=0.1186 \pm 0.0021$$ α s ( M Z 2 ) = 0.1186 ± 0.0021 ].

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Probing the singularities of the Landau-Gauge gluon and ghost propagators with rational approximants

Boito

Cucchieri

London

et al. 2023

J. High Energ. Phys.

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We employ Padé approximants in the study of the analytic structure of the four-dimensional SU(2) Landau-gauge gluon and ghost propagators in the infrared regime. The approximants, which are model independent, serve as fitting functions for the lattice data. We carefully propagate the uncertainties due to the fitting procedure, taking into account all possible correlations. For the gluon-propagator data, we confirm the presence of a pair of complex poles at $$ {p}_{\textrm{pole}}^2 $$ p pole 2 = [(−0.37 ± 0.05stat± 0.08sys) ± i (0.66 ± 0.03stat± 0.02sys)] GeV2, where the first error is statistical and the second systematic. The existence of this pair of complex poles, already hinted upon in previous works, is thus put onto a firmer basis, thanks to the model independence and to the careful error propagation of our analysis. For the ghost propagator, the Padés indicate the existence of a single pole at p2 = 0, as expected. In this case, our results also show evidence of a branch cut along the negative real axis of p2. This is corroborated with another type of approximant, the D-Log Padés, which are better suited to studying functions with a branch cut and are applied here for the first time in this context. Due to particular features and limited statistics of the gluon-propagator data, our analysis is inconclusive regarding the presence of a branch cut in the gluon case.

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Strong coupling from an improved τ vector isovector spectral function

Cited by 31 publications

References 87 publications

On the difference between FOPT and CIPT for hadronic tau decays

On the difference between FOPT and CIPT for hadronic tau decays

Determination of perturbative QCD coupling from ALEPH $$\tau $$ decay data using pinched Borel–Laplace and Finite Energy Sum Rules

Probing the singularities of the Landau-Gauge gluon and ghost propagators with rational approximants

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