Lattice QCD calculation of the $π^0$-pole contribution to the hadronic light-by-light scattering in the anomalous magnetic moment of the muon

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Main Authors: Lin, Tian, Bruno, Mattia, Feng, Xu, Jin, Lu-Chang, Lehner, Christoph, Liu, Chuan, Luo, Qi-Yuan
Format: Preprint
Published: 2024
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author Lin, Tian
Bruno, Mattia
Feng, Xu
Jin, Lu-Chang
Lehner, Christoph
Liu, Chuan
Luo, Qi-Yuan
author_facet Lin, Tian
Bruno, Mattia
Feng, Xu
Jin, Lu-Chang
Lehner, Christoph
Liu, Chuan
Luo, Qi-Yuan
contents We develop a method to compute the pion transition form factor directly at arbitrary space-like photon momenta and use it to determine the $π^0$-pole contribution to the hadronic light-by-light scattering in the anomalous magnetic moment of the muon. The calculation is performed using eight gauge ensembles generated with 2+1 flavor domain wall fermions, incorporating multiple pion masses, lattice spacings, and volumes. By introducing a pion structure function and performing a Gegenbauer expansion, we demonstrate that about 98\% of the $π^0$-pole contribution can be extracted in a model-independent manner, thereby ensuring that systematic effects are well controlled. After applying finite-volume corrections, as well as performing chiral and continuum extrapolations, we obtain the final result for the $π^0$-pole contribution to the hadronic light-by-light scattering in the muon's anomalous magnetic moment, $a_μ^{π^0\mathrm{-pole}}=61.2(1.7)\times 10^{-11}$, and the $π^0$ decay width, $Γ_{π^0\to γγ}=7.60(27)$ eV.
format Preprint
id arxiv_https___arxiv_org_abs_2411_06349
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Lattice QCD calculation of the $π^0$-pole contribution to the hadronic light-by-light scattering in the anomalous magnetic moment of the muon
Lin, Tian
Bruno, Mattia
Feng, Xu
Jin, Lu-Chang
Lehner, Christoph
Liu, Chuan
Luo, Qi-Yuan
High Energy Physics - Lattice
High Energy Physics - Phenomenology
We develop a method to compute the pion transition form factor directly at arbitrary space-like photon momenta and use it to determine the $π^0$-pole contribution to the hadronic light-by-light scattering in the anomalous magnetic moment of the muon. The calculation is performed using eight gauge ensembles generated with 2+1 flavor domain wall fermions, incorporating multiple pion masses, lattice spacings, and volumes. By introducing a pion structure function and performing a Gegenbauer expansion, we demonstrate that about 98\% of the $π^0$-pole contribution can be extracted in a model-independent manner, thereby ensuring that systematic effects are well controlled. After applying finite-volume corrections, as well as performing chiral and continuum extrapolations, we obtain the final result for the $π^0$-pole contribution to the hadronic light-by-light scattering in the muon's anomalous magnetic moment, $a_μ^{π^0\mathrm{-pole}}=61.2(1.7)\times 10^{-11}$, and the $π^0$ decay width, $Γ_{π^0\to γγ}=7.60(27)$ eV.
title Lattice QCD calculation of the $π^0$-pole contribution to the hadronic light-by-light scattering in the anomalous magnetic moment of the muon
topic High Energy Physics - Lattice
High Energy Physics - Phenomenology
url https://arxiv.org/abs/2411.06349