### Speaker

Mr
Malwin Niehus
(HISKP, University of Bonn)

### Description

Usually the simulation of scattering processes in lattice QCD is carried out at unphysical high values of the quark masses [1]. Hence, a method to extrapolate data obtained in lattice calculations to physical masses is needed to allow for comparison between theory and experiment. To obtain a sound extrapolation, dispersion relations and chiral perturbation theory can be invoked. While a simple combined approach known as the inverse amplitude method allows for a successful extrapolation of $\pi\pi\to\pi\pi$ data [2], a more complicated framework is needed for inelastic processes such as $\gamma\pi\to\pi\pi$. By extending the dispersive description derived in Ref. [3], the extrapolation can be performed for $\gamma\pi\to\pi\pi$ both for on-shell as well as virtual photons. This particular process is interesting due to both its contribution to the anomalous magnetic moment of the muon and its connection to the axial anomaly.
References:
- [1] Briceno et al.: https://arxiv.org/abs/1507.06622
- [2] Bolton, Briceno, Wilson: https://arxiv.org/abs/1507.07928
- [3] Hoferichter, Kubis, Sakkas: https://arxiv.org/abs/1210.6793

### Summary

We investigate the quark mass dependence of the process $\gamma\pi\to\pi\pi$ using dispersion relations and chiral perturbation theory.

### Primary author

Mr
Malwin Niehus
(HISKP, University of Bonn)

### Co-authors

Prof.
Bastian Kubis
(University of Bonn)
Dr
Martin Hoferichter
(University of Washington)