Johan Bijinens
Hadronic light-by-light contribution to $a_{\mu}$ : extended Nambu-Jona-Lasinio, chiral quark models and chiral Lagrangians


This talk discusses our old work on the hadronic light-by-light contribution to the muon anomalous magnetic moment and some more recent contributions. I discuss the various contributions starting with pseudo-scalar meson exchange, the quark- and pion-loop, as well as scalar and $a_{1}$-exchange. For the ${\pi}^{0}$-exchange I point out a possible large enhancement when only connected contributions are included. For the quark-loop I include some comments about the more recent estimates of this contribution. The pion-loop is discussedin more detail, in particular I discuss our unpublished work on including effects from $a_{1}$ and the polarizability.

LU TP 15-46