Role of the σ resonance in determining the convergence of chiral perturbation theory

Journal Article (Journal Article)

The dimensionless parameter ξ=Mπ2/(16π2Fπ2), where Fπ is the pion decay constant and Mπ is the pion mass, is expected to control the convergence of chiral perturbation theory applicable to QCD. Here we demonstrate that a strongly coupled lattice gauge theory model with the same symmetries as two-flavor QCD but with a much lighter σ-resonance is different. We first confirm that the leading low-energy constants appearing in the chiral Lagrangian are the same when calculated from the p-regime and the -regime as expected. However, ξ 0.002 is necessary before 1-loop chiral perturbation theory predicts the data within 1%. For ξ>0.0035 the data begin to deviate dramatically from 1-loop chiral perturbation theory predictions. We argue that this qualitative change is due to the presence of a light σ-resonance in our model. Our findings may be useful for lattice QCD studies. © 2008 The American Physical Society.

Full Text

Duke Authors

Cited Authors

  • Cecile, DJ; Chandrasekharan, S

Published Date

  • May 5, 2008

Published In

Volume / Issue

  • 77 / 9

Electronic International Standard Serial Number (EISSN)

  • 1550-2368

International Standard Serial Number (ISSN)

  • 1550-7998

Digital Object Identifier (DOI)

  • 10.1103/PhysRevD.77.091501

Citation Source

  • Scopus