In the framework of the electroweak chiral Lagrangian, the one-loop induced effects of the anomalous $tbW$ coupling, which includes both left- and right-handed complex components, on the static electromagnetic properties of the $W$ boson and the $t$ quark are studied. The attention is focused mainly on the $CP$-violating electromagnetic properties. It is found that the $tbW$ anomalous coupling can induce both $CP$-violating moments of the $W$ boson, namely, its electric dipole (${\tilde{\mu }}_W$) and magnetic quadrupole (${\tilde{Q}}_W$) moments. As far as the $t$ quark is concerned, a potentially large electric dipole moment ($d_t$) can arise due to the anomalous $tbW$ coupling. The most recent bounds on the $tbW$ coupling left- and right-handed parameters from $B$ meson physics lead to the following estimates ${\tilde{\mu }}_W\sim 4\times {10}^{-23}-4\times {10}^{-22}\mathrm{e}·\mathrm{cm}$ and ${\tilde{Q}}_W\sim {10}^{-38}-{10}^{-37}\mathrm{e}·{\mathrm{cm}}^2$, which are 7 and 14 orders of magnitude larger than the standard model (SM) predictions, whereas $d_t$ may be as large as ${10}^{-22}\mathrm{e}·\mathrm{cm}$, which is about 8 orders of magnitude larger than its SM counterpart.

• Received 29 November 2006

DOI:https://doi.org/10.1103/PhysRevD.75.073017