Lattice calculation of the pion transition form factor \π⁰ \→\n \γ^* \γ^*

2016/11/07 by Antoine Gérardin, Harvey B. Meyer, Gérardin, Antoine +3
Physics and Astronomy · #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #High-Energy Particle Collisions Research

paper · pdf · doi:10.48550/arxiv.1611.02190

Abstract

We calculate the pion transition form factor cal\nF_{\π⁰\γ^*\γ^*}(q₁²,q₂²), which describe the interaction of an\non-shell pion with two off-shell photons, using lattice QCD simulations with\ntwo degenerate flavors of dynamical quarks. This form factor is the main\ningredient in the calculation of the pion-pole contribution to hadronic\nlight-by-light scattering in the muon g-2, a_\μ^{\HLbL; \π0}. We\nfocus our study on the spacelike region with photon virtualities up to\n1.5~\GeV², not yet measured experimentally. Several lattice spacings\nand pion masses are used to extrapolate the results to the physical point and a\ncomparison with different phenomenological models is performed. Finally, we use\nour extrapolated form factor to provide a lattice determinaiton of\na_\μ^{\HLbL; \π0}.\n

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