Chiral Perturbation Theory with Virtual Photons and Leptons

por Dr. Helmut Neufeld (ITP, Univ. Wien, Austria)

jueves 28 oct. 1999 11:30 → 12:30 Europe/Madrid

Sala de Juntas del IFIC (Edf. Institutos de Investigacion)

I discuss a low-energy effective field theory which allows the full treatment of isospin-breaking effects in semileptonic weak interactions. To this end, the particle spectrum of chiral perturbation theory with virtual photons is enlarged by including also the light leptons as dynamical degrees of freedom. The additional one-loop divergences generated by the presence of virtual leptons are determined by using super-heat-kernel techniques. The full list of associated counterterms is given. I illustrate the use of this effective theory by applying it to the decays $\pi \rightarrow \ell \nu$ and $K \rightarrow \ell \nu$. (See also hep-ph/9909284 for further information.)