Masaharu Tanabashi

Renormalization in the Gauged Nambu-Jona-Lasinio Model

Based on the Cornwall-Jackiw-Tomboulis effective potential, we extensively study nonperturbative renormalization of the gauged Nambu-Jona-Lasinio model in the ladder approximation with standing gauge coupling. Although the pure Nambu-Jona-Lasinio model is not renormalizable, presence of the gauge interaction makes it possible that the theory is renormalized as an interacting continuum theory at the critical line in the ladder approximation. Extra higher dimensional operators («counter terms») are not needed for the theory to be renormalized. By virtue of the effective potential approach, the renormalization («symmetric renormalization») is performed in a phase-independent manner both for the symmetric and the spontaneously broken phase of the chiral symmetry

Chiral perturbation to one loop including the ϱ meson

Abstract We formulate the chiral perturbation theory at the one loop level in the effective lagrangian including the ϱ meson as a dynamical gauge boson of a hidden local symmetry (HLS). The size of radiative correction to the phenomenological parameter a of HLS is estimated to be about 10%. The complete list of O ( E 4 ) terms is given and the one loop counter terms are determined explicitly in the N flavor model. We also obtain matching conditions to the conventional chiral perturbation of Gasser and Leutwyler in the chiral limit in a renormalization scale independent manner. We find that Gasser-Leutwylers estimates for L 9.10 are saturated by ϱ and its one loop contributions without introducing non-minimal couplings of the π−ϱ system, suggesting the absence of the tree level a 1 meson contributions.

Formulations of spin 1 resonances in the chiral Lagrangian

Abstract The relation of the hidden local symmetry formulation with non-minimal interactions and the anti-symmetric tensor field method of ϱ- and α 1 -mesons in the chiral Lagrangian is investigated by using the auxiliary field method. We obtain explicit correspondence of parameters in both formulations. The massless limit of the ϱ-meson in the anti-symmetric tensor field formalism is studied in the equivalent vector field Lagrangian, in which the gauge properties of the massless vector field are manifest.