https://doi.org/10.1140/epja/i2010-10955-5
Regular Article - Theoretical Physics
How to define physical properties of unstable particles
1
Institut für Kernphysik, Johannes Gutenberg-Universität, D-55099, Mainz, Germany
2
High Energy Physics Institute, Tbilisi State University, Tbilisi, Georgia
* e-mail: gegelia@kph.uni-mainz.de
Received:
17
February
2010
Revised:
2
March
2010
Accepted:
8
March
2010
Published online:
20
April
2010
In the framework of effective quantum field theory we address the definition of physical quantities characterizing unstable particles. With the aid of a one-loop calculation, we study this issue in terms of the charge and the magnetic moment of a spin-1/2 resonance. By appealing to the invariance of physical observables under field redefinitions we demonstrate that physical properties of unstable particles should be extracted from the residues at complex (double) poles of the corresponding S -matrix.
© SIF, Springer-Verlag Berlin Heidelberg, 2010
