Nuclear Physics Seminar
Baryon chiral perturbation theory: one loop and beyond
Matthias R. Schindler (Ohio U.)
For energies below 1 GeV perturbative calculations in the
strong
coupling $\alpha_s$ of QCD are not meaningful. One of
the
theoretical tools to explore this energy region is the use of
an
effective field theory, chiral perturbation theory
(ChPT). After
giving an introduction to the underlying ideas of ChPT
I will
focus on the one-nucleon sector. In particular, issues
of
renormalization and power counting will be addressed. With
the
development of new renormalization schemes the evaluation
of
contributions beyond one-loop order has become possible in
a
manifestly Lorentz-invariant formulation. I will describe
to
different approaches to higher-order calculations: the
inclusion
of additional degrees of freedom and the explicit
calculation of
two-loop diagrams. Results for the nucleon form
factors and the
nucleon mass will be presented.
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