Johan Bijnens
Professor, Deputy Head of Division
Low-energy behaviour of two-point functions of quark currents
Author
Summary, in English
We discuss vector, axial-vector, scalar and pseudoscalar two-point functions at low and intermediate energies. We first review what is known from chiral perturbation theory, as well as from a heat kernel expansion within the context of an extended Nambu-Jona-Lasinio (ENJL) model. We derive then these two-point functions to all orders in the momenta and to leading order in 1/N c within the framework of this model. We find an improved high-energy behaviour and a general way of parametrizing them that shows relations between some of the two-point functions, which are also valid in the presence of gluonic interactions. The similarity between the shape of the experimentally known spectral functions and the ones we derive, is greatly improved with respect to those predicted by the usual constituent quark like models. We also obtain the scalar mass M s =2 M Q independent of the regularization scheme. In the end, we calculate fully an example of a nonleptonic matrix element in the ENJL-model, the π + -π 0 electromagnetic mass difference and find good agreement with the measured value.
Publishing year
1994-09-01
Language
English
Pages
437-454
Publication/Series
Zeitschrift für Physik C Particles and Fields
Volume
62
Issue
3
Document type
Journal article
Publisher
Springer
Topic
- Subatomic Physics
Status
Published
ISBN/ISSN/Other
- ISSN: 0170-9739