### Speaker

Mr
Malwin Niehus
(Helmholtz Institut für Strahlen- und Kernphysik, Universität Bonn and Bonn-Cologne Graduate School of Physics and Astronomy)

### 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 (ChPT) can be invoked. While a simple combined approach known as the inverse amplitude method (IAM) allows for a successful extrapolation of $\pi\pi\rightarrow\pi\pi$ data [2], a more complicated framework is needed for inelastic processes such as $\gamma\pi\rightarrow\pi\pi$. By extending the dispersive description derived in Ref. [3], the extrapolation can be performed for $\gamma\pi\rightarrow\pi\pi$. 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/1210.6793v2

### Summary

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

### Primary author

Mr
Malwin Niehus
(Helmholtz Institut für Strahlen- und Kernphysik, Universität Bonn and Bonn-Cologne Graduate School of Physics and Astronomy)

### Co-authors

Bastian Kubis
(Bonn University)
Martin Hoferichter
(Institute for Nuclear Theory, University of Washington, Seattle)