SU(2) heavy baryon chiral perturbation theory for one- and two-nucleon processes: Application to pion double charge exchange to one loop
The thesis is concerning the study of strong interaction processes involving pions and nucleons (and nuclei) at low energies in the framework of an effective field theory generically referred to as Chiral Perturbation Theory. There are two goals of the thesis. The first is to develop a method to construct the nonrelativistic Lagrangian for interaction of arbitrary number of pions and off-shell nucleons, directly within the framework of the nonrelativistic effective field theory (Heavy Baryon Chiral Perturbation Theory). The new work has been to develop a method to implement charge conjugation invariance (which is conventionally imposed at the relativistic level) directly within the nonrelativistic framework, along with other symmetries of QCD, to construct the Heavy Baryon Chiral Perturbation Lagrangian. The effective Lagrangian has been constructed through the third ('chiral') order, and the fourth for even number of pions (interacting with a single nucleon). An analysis of the on-shell reduction through the third order, is also done. The second goal is to calculate the scattering amplitude for the 2-nucleon tree and 1-loop graphs for pion double charge exchange in a nuclear target at threshold and in the static limit, in the framework of Heavy Baryon Chiral Perturbation Theory. One finds that unlike the 1-nucleon-1-loop corrections (for 1-nucleon processes), one gets a very small correction from the 2-nucleon-1-loop (pion double charge exchange) graphs. The issue of renormalization by 2π - 2nucleon contact terms is also discussed.
- Pub Date:
- July 1998
- Physics: Nuclear, Physics: Elementary Particles and High Energy