Speaker
Description
We investigate the neutral pion transition form factor $F_{\pi^0\gamma^\ast\gamma^\ast}(q_1^2,q_2^2)$ in lattice QCD and confirm that the connected and disconnected contributions, in the short-distance regime with a fixed time integration, have the same sign. We employ the recently proposed blending method, which supplies an unbiased and cheap estimators for the required all-to-all propagators.
The external pion states are treated within the distillation framework, while the electromagnetic currents are evaluated via blending method.
Numerical tests are performed on an $N_f=2+1$ lattice ensemble. Our result shows that the contribution of the disconnected part is approximately $1\%$ of that of the connected part and enables constructive interference of probability amplitudes.
