scholarly journals Hadronic light-by-light scattering contribution to the muon g-2 from lattice QCD: Methodology

Author(s):  
Masashi Hayakawa ◽  
Tom Blum ◽  
Taku Izubuchi ◽  
Norikazu Yamada
2019 ◽  
Vol 218 ◽  
pp. 01001
Author(s):  
Andreas Nyffeler

We briefly review the current status of the hadronic light-by-light scattering contribution to the anomalous magnetic moment of the muon. Based on various model calculations in the literature, we obtain the estimate $ \mathop a\nolimits_\mu ^{HLbL} = (102 \pm 39) \times \mathop {10}\nolimits^{ - 11} $. Recent developments including more model-independent approaches using dispersion relations and lattice QCD, that could lead to a more reliable estimate, are also discussed.


2018 ◽  
Vol 179 ◽  
pp. 01017 ◽  
Author(s):  
Nils Asmussen ◽  
Antoine Gérardin ◽  
Jeremy Green ◽  
Oleksii Gryniuk ◽  
Georg von Hippel ◽  
...  

We briefly review several activities at Mainz related to hadronic light-by-light scattering (HLbL) using lattice QCD. First we present a position-space approach to the HLbL contribution in the muon g̅2, where we focus on exploratory studies of the pion-pole contribution in a simple model and the lepton loop in QED in the continuum and in infinite volume. The second part describes a lattice calculation of the double-virtual pion transition form factor Fπ0γ*γ* (q21; q21) in the spacelike region with photon virtualities up to 1.5 GeV2 which paves the way for a lattice calculation of the pion-pole contribution to HLbL. The third topic involves HLbL forward scattering amplitudes calculated in lattice QCD which can be described, using dispersion relations (HLbL sum rules), by γ*γ* → hadrons fusion cross sections and then compared with phenomenological models.


2021 ◽  
Vol 81 (7) ◽  
Author(s):  
En-Hung Chao ◽  
Renwick J. Hudspith ◽  
Antoine Gérardin ◽  
Jeremy R. Green ◽  
Harvey B. Meyer ◽  
...  

AbstractWe compute the hadronic light-by-light scattering contribution to the muon $$g-2$$ g - 2 from the up, down, and strange-quark sector directly using lattice QCD. Our calculation features evaluations of all possible Wick-contractions of the relevant hadronic four-point function and incorporates several different pion masses, volumes, and lattice-spacings. We obtain a value of $$a_\mu ^{\text {Hlbl}}= 106.8(15.9) \times 10^{-11}$$ a μ Hlbl = 106.8 ( 15.9 ) × 10 - 11 (adding statistical and systematic errors in quadrature), which is consistent with current phenomenological estimates and a previous lattice determination. It now appears conclusive that the hadronic light-by-light contribution cannot explain the current tension between theory and experiment for the muon $$g-2$$ g - 2 .


2018 ◽  
Vol 98 (7) ◽  
Author(s):  
Antoine Gérardin ◽  
Jeremy Green ◽  
Oleksii Gryniuk ◽  
Georg von Hippel ◽  
Harvey B. Meyer ◽  
...  

1996 ◽  
Vol 54 (5) ◽  
pp. 3137-3153 ◽  
Author(s):  
M. Hayakawa ◽  
T. Kinoshita ◽  
A. I. Sanda

2018 ◽  
Vol 166 ◽  
pp. 00022 ◽  
Author(s):  
Fred Jegerlehner

I present a status report of the hadronic vacuum polarization effects for the muon g–2, to be considered as an update of [1]. The update concerns recent new inclusive R measurements from KEDR in the energy range 1.84 to 3.72 GeV. For the leading order contributions I find [see formula in PDF] based on e+e- data [incl. τ data], [see formula in PDF] (NLO) and [see formula in PDF] (NNLO). Collecting recent progress in the hadronic light-by-light scattering I adopt π0, η, η' [95 ± 12] + axial-vector [8 ± 3] + scalar [-6 ± 1] + π, K loops [-20 ± 5] + quark loops [22 ± 4] + tensor [1 ± 0] + NLO [3 ± 2] which yields [see formula in PDF]. With these updates I find [see formula in PDF] a 4.1 σ deviation. Recent lattice QCD results and future prospects to improve hadronic contributions are discussed.


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