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Volume 256 - 34th annual International Symposium on Lattice Field Theory (LATTICE2016) - Hadron Structure
Lattice calculation of the pion transition form factor $\pi^0 \to \gamma^* \gamma^*$
A. Gerardin,* H.B. Meyer, A. Nyffeler
*corresponding author
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Pre-published on: 2016 December 27
Published on: 2017 March 24
We calculate the pion transition form factor $\FF(q_1^2,q_2^2)$, which describe the interaction of an on-shell pion with two off-shell photons, using lattice QCD simulations with two degenerate flavors of dynamical quarks. This form factor is the main ingredient in the calculation of the pion-pole contribution to hadronic light-by-light scattering in the muon $g-2$, $\amu$. We focus our study on the spacelike region with photon virtualities up to $1.5~\GeV^2$, not yet measured experimentally. Several lattice spacings and pion masses are used to extrapolate the results to the physical point and a comparison with different phenomenological models is performed. Finally, we use our extrapolated form factor to provide a lattice determinaiton of $\amu$.
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