Tenth-order QED contribution to the lepton anomalous magnetic moment: Sixth-order vertices containing an internal light-by-light-scattering subdiagram

Aoyama, T.; Hayakawa, Masashi; Kinoshita, T.; Nio, Makiko

doi:10.1103/physrevd.85.093013

Cited by 22 publications

(8 citation statements)

References 39 publications

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“…99 is described in detail in Refs. [724,[740][741][742][743][744][745][746][747][748][749]. A part of the tenth-order contribution coming from the diagrams without a fermion loop shown as Set V of Fig.…”

Section: Mass-independent Contributionsmentioning

confidence: 99%

The anomalous magnetic moment of the muon in the Standard Model

Aoyama,

Asmussen,

Benayoun

et al. 2020

Preprint

148

296

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We review the present status of the Standard Model calculation of the anomalous magnetic moment of the muon. This is performed in a perturbative expansion in the fine-structure constant α and is broken down into pure QED, electroweak, and hadronic contributions. The pure QED contribution is by far the largest and has been evaluated up to and including O(α 5 ) with negligible numerical uncertainty. The electroweak contribution is suppressed by (m µ /M W ) 2 and only shows up at the level of the seventh significant digit. It has been evaluated up to two loops and is known to better than one percent. Hadronic contributions are the most difficult to calculate and are responsible for almost all of the theoretical uncertainty. The leading hadronic contribution appears at O(α 2 ) and is due to hadronic vacuum polarization, whereas at O(α 3 ) the hadronic light-by-light scattering contribution appears. Given the low characteristic scale of this observable, these contributions have to be calculated with nonperturbative methods, in particular, dispersion relations and the lattice approach to QCD. The largest part of this review is dedicated to a detailed account of recent efforts to improve the calculation of these two contributions with either a data-driven, dispersive approach, or a first-principle, lattice-QCD approach. The final result reads a SM µ = 116 591 810(43) × 10 −11 and is smaller than the Brookhaven measurement by 3.7σ. The experimental uncertainty will soon be reduced by up to a factor four by the new experiment currently running at Fermilab, and also by the future J-PARC experiment. This and the prospects to further reduce the theoretical uncertainty in the near future-which are also discussed here-make this quantity one of the most promising places to look for evidence of new physics.

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Section: Mass-independent Contributionsmentioning

confidence: 99%

The anomalous magnetic moment of the muon in the Standard Model

Aoyama,

Asmussen,

Benayoun

et al. 2020

Preprint

148

296

View full text Add to dashboard Cite

show abstract

“…Very recently, Kinoshita and his collaborators completed the heroic calculation of the 12672 five-loop diagrams contributing to the tenth-order coefficient A (10) 1 [33,[35][36][37][38][39][40][41][42][43][44][45][46]. Their result is A (10) 1 = 9.16 (58).…”

Section: Jhep11(2012)113mentioning

confidence: 99%

Testing new physics with the electron g − 2

Giudice

Paradisi

Passera

2012

J. High Energ. Phys.

227

230

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We argue that the anomalous magnetic moment of the electron (a e ) can be used to probe new physics. We show that the present bound on new-physics contributions to a e is 8 × 10 −13 , but the sensitivity can be improved by about an order of magnitude with new measurements of a e and more refined determinations of α in atomic-physics experiments. Tests on new-physics effects in a e can play a crucial role in the interpretation of the observed discrepancy in the anomalous magnetic moment of the muon (a µ ). In a large class of models, new contributions to magnetic moments scale with the square of lepton masses and thus the anomaly in a µ suggests a new-physics effect in a e of (0.7±0.2)×10 −13 . We also present examples of new-physics theories in which this scaling is violated and larger effects in a e are expected. In such models the value of a e is correlated with specific predictions for processes with violation of lepton number or lepton universality, and with the electric dipole moment of the electron.

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“…2 ðm e =m μ Þ has been evaluated numerically [16][17][18][19][20][21][22][23][24][25]. Some of the tenth-order diagrams have been independently calculated and checked [26].…”

Section: Introductionmentioning

confidence: 99%

Revised and improved value of the QED tenth-order electron anomalous magnetic moment

2018

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In order to improve the theoretical prediction of the electron anomalous magnetic moment a e we have carried out a new numerical evaluation of the 389 integrals of Set V, which represent 6,354 Feynman vertex diagrams without lepton loops. During this work, we found that one of the integrals, called X024, was given a wrong value in the previous calculation due to an incorrect assignment of integration variables. The correction of this error causes a shift of −1.26 to the Set V contribution, and hence to the tenth-order universal (i.e., mass-independent) term A1 . The previous evaluation of all other 388 integrals is free from errors and consistent with the new evaluation. Combining the new and the old (excluding X024) calculations statistically, we obtain 7.606ð192Þðα=πÞ 5 as the best estimate of the Set V contribution. Including the contribution of the diagrams with fermion loops, the improved tenth-order universal term becomes A ð10Þ 1 ¼ 6.675ð192Þ. Adding hadronic and electroweak contributions leads to the theoretical prediction a e ðtheoryÞ ¼ 1159652182.032ð720Þ × 10 −12 . From this and the best measurement of a e , we obtain the inverse fine-structure constant α −1 ða e Þ ¼ 137.0359991491ð331Þ. The theoretical prediction of the muon anomalous magnetic moment is also affected by the update of QED contribution and the new value of α, but the shift is much smaller than the theoretical uncertainty.

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Tenth-order QED contribution to the lepton anomalous magnetic moment: Sixth-order vertices containing an internal light-by-light-scattering subdiagram

Cited by 22 publications

References 39 publications

The anomalous magnetic moment of the muon in the Standard Model

The anomalous magnetic moment of the muon in the Standard Model

Testing new physics with the electron g − 2

Revised and improved value of the QED tenth-order electron anomalous magnetic moment

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