2021 Impact factor 4.991
Particles and Fields
Eur. Phys. J. C 7, 507-524
DOI 10.1007/s100529801024

Generalized heavy baryon chiral perturbation theory

R. Baur, J. Kambor

Institut für Theoretische Physik, Universität Zürich, CH-8057 Zürich, Switzerland

Received: 22 July 1998 / Revised version: 2 September 1998 / Published online: 2 November 1998

Standard SU(2) Heavy Baryon Chiral Perturbation Theory is extended in order to include the case of small or even vanishing quark condensate. The effective lagrangian is given to ${\cal O}(p^2)$ in its most general form and to ${\cal O}(p^3)$ in the scalar sector. A method is developed to efficiently construct the relativistic baryonic effective lagrangian for chiral SU(2) to all orders in the chiral expansion. As a first application, mass- and wave-function renormalization as well as the scalar form factor of the nucleon is calculated to ${\cal O}(p^3)$. The result is compared to a dispersive analysis of the nucleon scalar form factor adopted to the case of a small quark condensate. In this latter analysis, the shift of the scalar form factor between the Cheng-Dashen point and zero momentum transfer is found to be enhanced over the result assuming strong quark condensation by up to a factor of two, with substantial deviations starting to be visible for $r=m_s/\hat{m}\mathrel{\mathchoice {\vcenter{\offinterlineskip\halign{\hfil
 ...{\offinterlineskip\halign{\hfil$\scriptscriptstyle ... .

Copyright Springer-Verlag