The physics of hadrons

Neubert, Matthias

doi:10.1016/0550-3213(96)00002-8

Cited by 66 publications

(80 citation statements)

References 68 publications

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“…The analogous determination of α S (m τ ) and α S (m Z 0 ) using the calculation of [290] results in α S (m τ ) = 0.303 ± 0.003(exp.) ± 0.002(non − pert.)…”

Section: Decay Of the τ Leptonmentioning

confidence: 97%

“…The original calculation of [288] has been improved in [289] by a more accurate treatment of the running strong coupling in the calculation using the full β-function instead of an approximation. A third calculation includes a resummation of the effects of renormalon chains [290]. The non-perturbative contribution can be analysed in the framework of the Operator Product Expansion (OPE) as a power series in terms of 1/m 2 τ [288] δ kl non−pert,v/a = D=2,4,6,...…”

Section: Decay Of the τ Leptonmentioning

confidence: 99%

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Tests of quantum chromo dynamics at e⁺e⁻ colliders

Kluth¹

2006

Rep. Prog. Phys.

107

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Abstract.The current status of tests of the theory of strong interactions, Quantum Chromo Dynamics (QCD), with data from hadron production in e + e − annihilation experiments is reviewed. The LEP experiments ALEPH, DELPHI, L3 and OPAL have published many analyses with data recorded on the Z 0 resonance at √ s = 91.2 GeV and above up to √ s > 200 GeV. There are also results from SLD at √ s = 91.2 GeV and from reanalysis of data recorded by the JADE experiment at 14 ≤ √ s ≤ 44 GeV. The results of studies of jet and event shape observables, of particle production and of quark gluon jet differences are compared with predictions by perturbative QCD calculations. Determinations of the strong coupling constant α S (m Z 0 ) from jet and event shape observables, scaling violation and fragmentation functions, inclusive observables from Z 0 decays, hadronic τ decays and hadron production in low energy e + e − annihilation are discussed. Updates of the measurements are performed where new data or improved calculations have become available. The best value of α S (m Z 0 ) is obtained from an average of measurements using inclusive observables calculated in NNLO QCD: α S (m Z 0 ) = 0.1211 ± 0.0021 where the error is dominated by theoretical systematic uncertainties. The other measurements of α S (m Z 0 ) are in good agreement with this value. Finally, investigations of the gauge structure of QCD are summarised and the best values for the colour factors are determined: C A = 2.89 ± 0.21 C F = 1.30 ± 0.09 with errors dominated by systematic uncertainties and in good agreement with the expectation from QCD with the SU(3) gauge symmetry.

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“…The analogous determination of α S (m τ ) and α S (m Z 0 ) using the calculation of [290] results in α S (m τ ) = 0.303 ± 0.003(exp.) ± 0.002(non − pert.)…”

Section: Decay Of the τ Leptonmentioning

confidence: 97%

Section: Decay Of the τ Leptonmentioning

confidence: 99%

Tests of quantum chromo dynamics at e⁺e⁻ colliders

Kluth¹

2006

Rep. Prog. Phys.

107

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“…The last two coefficients are renormalization scheme dependent and the quoted values belong to the MS-scheme. The third method considered in this paper resums the leading term of the β-function to all orders in α s by inserting so-called Renormalon Chains (RCPT) [15][16][17] 2 . One of the leading theoretical uncertainties for FOPT and CIPT comes from the unknown O (α 4 s ) correction K 4 .…”

Section: Perturbative Correction Terms δ Kl Pertmentioning

confidence: 99%

Measurement of the strong coupling constant $\alpha_{\rm s}$ and the vector and axial-vector spectral functions in hadronic tau decays

Ackerstaff¹,

Alexander²,

Allison³

et al. 1999

Eur. Phys. J. C

180

152

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The spectral functions of the vector current and the axial-vector current have been measured in hadronic τ decays using the OPAL detector at LEP. Within the framework of the Operator Product Expansion a simultaneous determination of the strong coupling constant α s , the non-perturbative operators of dimension 6 and 8 and of the gluon condensate has been performed. Different perturbative descriptions have been compared to the data. The Contour Improved Fixed Order Perturbation Theory gives α s (m 2 τ ) = 0.348±0.009 exp ±0.019 theo at the τ -mass scale and α s (m 2 Z ) = 0.1219±0.0010 exp ±0.0017 theo at the Z 0 -mass scale. The values obtained for α s (m 2 Z ) using Fixed Order Perturbation Theory or Renormalon Chain Resummation are 2.3 % and 4.1 % smaller, respectively. The 'running' of the strong coupling between s 0 ≃ 1.3 GeV 2 and s 0 = m 2 τ has been tested from direct fits to the integrated differential hadronic decay rate R τ (s 0 ). A test of the saturation of QCD sum rules at the τ -mass scale has been performed.

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“…where a s ͑s 0 ͒ is defined in the minimal subtraction ͑ MS ͒ renormalization scheme, d ͑k͒ 1 1, and the next three coefficients are given by [8,9] (5)…”

Section: Maria Gironementioning

confidence: 99%

“…[7], using data on the e 1 e 2 ! hadrons cross section.The t decay rate into hadrons can be written in terms of moments M ͑J͒ k of the absorptive part of current-current correlation functions of angular momentum J [8,9]. The quantity R t ͑s 0 ͒ is given by…”

mentioning

confidence: 99%

Test of the Running ofαsinτDecays

Girone

Neubert

1996

Phys. Rev. Lett.

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The t decay rate into hadrons of invariant mass smaller than p s 0 ¿ L QCD can be calculated in QCD assuming global quark-hadron duality. It is shown that this assumption holds for s 0 . 0.7 GeV 2 . From measurements of the hadronic mass distribution, the running coupling constant a s ͑s 0 ͒ is extracted in the range 0.7 GeV 2 , s 0 , m 2 t . At s 0 m 2 t , the result is a s ͑m 2 t ͒ 0.329 6 0.030. The running of a s is in good agreement with the QCD prediction.PACS numbers: 12.38. Aw, 11.10.Hi, 12.38.Qk, 13.35.Dx The scale dependence of coupling constants is one of the key features of renormalizable quantum field theories. In QCD, the effective coupling constant a s ͑Q 2 ͒ is predicted to decrease with the momentum transfer Q 2 , a property referred to as asymptotic freedom [1]. This prediction has been tested by comparing data obtained from experiments operating at different energies [2]; it has also been studied in single high-energy experiments at ep and pp colliders, where a large range in Q 2 can be probed simultaneously [3]. Here we propose a test of the scale dependence of a s ͑Q 2 ͒ in the low-energy regionOur method is based on integrals of the invariant mass distribution in hadronic t decays. It provides a unique opportunity to test one of the most important predictions of QCD in a single experiment and at low energies, where the effect of the running of a s is most pronounced.We shall consider the t decay rate into hadrons of invariant mass squared smaller than s 0 , normalized to the leptonic decay rate,where dR t ͞ds is the inclusive hadronic spectrum. As long as s 0 ¿ L 2 QCD , the quantity R t ͑s 0 ͒ can be calculated in QCD using the operator product expansion (OPE) [4,5]. Applying the OPE in the physical region assumes global quark-hadron duality, i.e., that decay rates admit a QCD description after a "smearing" over a sufficiently wide energy interval has been performed [6], which in the present case is provided by the integration over the range 0 , s , s 0 . The question of how accurate this assumption is and for what values of s 0 it applies is a phenomenological one; it cannot be answered yet from theoretical grounds. Below, we shall investigate this question, comparing data with theoretical predictions based on the duality assumption. A similar test of duality has been performed in Ref. [7], using data on the e 1 e 2 ! hadrons cross section.The t decay rate into hadrons can be written in terms of moments M ͑J͒ k of the absorptive part of current-current correlation functions of angular momentum J [8,9]. The quantity R t ͑s 0 ͒ is given bywhere S EW Ӎ 1.0194 accounts for electroweak radiative corrections [10]. The moments can be written as contour integrals along a circle of radius s 0 in the complex plane. Since the only large mass scale in these integrals is s 0 , the OPE provides an expansion in powers of 1͞s 0 ,The leading term is given by perturbation theory alone. Terms suppressed by powers of 1͞s 0 consist of perturbative coefficients c ͑J͒ n multiplying dimensionful parameters ͗O...

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The physics of hadrons

Cited by 66 publications

References 68 publications

Tests of quantum chromo dynamics at e⁺e⁻ colliders

Tests of quantum chromo dynamics at e⁺e⁻ colliders

Measurement of the strong coupling constant $\alpha_{\rm s}$ and the vector and axial-vector spectral functions in hadronic tau decays

Test of the Running ofαsinτDecays

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The physics of hadrons

Cited by 66 publications

References 68 publications

Tests of quantum chromo dynamics at e+e− colliders

Tests of quantum chromo dynamics at e+e− colliders

Measurement of the strong coupling constant $\alpha_{\rm s}$ and the vector and axial-vector spectral functions in hadronic tau decays

Test of the Running ofαsinτDecays

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Tests of quantum chromo dynamics at e⁺e⁻ colliders

Tests of quantum chromo dynamics at e⁺e⁻ colliders