Non-contact interactions and the hadronic light-by-light contribution to the muon g-2

TL;DR

This paper reviews recent calculations of the hadronic light-by-light scattering contribution to the muon g-2, emphasizing the effects of momentum-dependent quark interactions and comparing different theoretical models.

Contribution

It provides a comparative analysis of Dyson-Schwinger and ENJL models, highlighting the significance of the quark-photon vertex structure in muon g-2 calculations.

Findings

Dyson-Schwinger approach shows less suppression than ENJL model.

Transverse quark-photon-vertex parts are crucial for accurate estimates.

Quantitative differences impact the theoretical prediction of muon g-2.

Abstract

We summarise recent results for the quark loop part of the light-by-light scattering contribution to the muons anomalous magnetic moment. In particular we focus on the impact of a momentum dependent quark and quark-photon vertex. We compare the Dyson-Schwinger description with that of the extended Nambu--Jona-Lasinio model (ENJL) and find important quantitative differences. In particular the transverse parts of the quark-photon-vertex, which serve as a dynamical extension of simple vector meson dominance models, do not yield the large suppression as found in the ENJL model.