1 research outputs found
Rho Meson Properties in the Chiral Theory Framework
We study the mass, width and couplings of the lightest resonance multiplet
with I(J^{PC})=1(1^{--}) quantum numbers. Effective field theories based on
chiral symmetry are employed in order to describe the form factor associated
with the two-pseudoscalar matrix element of the QCD vector current. The bare
poles of the intermediate resonances are regularized through a
Dyson-Schwinger-like summation. We explore the role of the resonance width in
physical observables and make a coupled-channel analysis of final-state
interactions. This provides many interesting properties, as the pole mass
M_rho{pole}= 764.1 +- 2.7 +4.0-2.5 MeV. At energies E~1 GeV, a second 1(1^{--})
resonance multiplet is considered in order to describe the data in a more
consistent way. From the phenomenologically extracted resonance couplings, we
obtain the chiral coupling L_9^r(mu0)= (7.04 +- 0.05 +0.19-0.27)* 10^{-3}, at
mu0=770$ MeV, and show how the running with the scale mu affects the resonance
parameters. A 1/N_C counting is adopted in this work and the consistency of the
large--N_C expansion is tested. Finally, we make an estimation of the
contribution from diagrams with resonances in crossed channels.Comment: 26 pages, 8 figures, Latex fil