Connecting the Quenched and Unquenched Worlds via the Large N_c World

Abstract

In the large N_c(number of colors) limit, quenched QCD and QCD are identical. This implies that, in the effective field theory framework, some of the low energy constants in (N_c=3) quenched QCD and QCD are the same up to higher-order corrections in the 1/N_c expansion. Thus the calculation of the nonleptonic kaon decays relevant for the Delta I=1/2 rule in the quenched approximation is expected to differ from the unquenched one by an O(1/N_c) correction. However, the calculation relevant to the CP-violation parameter epsilon'/epsilon would have a relatively big higher-order correction due to the large cancellation in the leading order. Some important weak matrix elements are poorly known that even constraints with 100% errors are interesting. In those cases, quenched calculations will be very useful.

8 pages, one figure; minor typos corrected

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Cited by in corpus (7)

• Towards grounding nuclear physics in QCD
• Electromagnetic and spin polarisabilities in lattice QCD
• Properties of the rho and sigma Mesons from Unitary Chiral Dynamics
• Partially-Quenched Nucleon-Nucleon Scattering
• The Chiral Extrapolation of Strange Matrix Elements in the Nucleon
• Generalised parton distributions of the pion in partially-quenched chiral perturbation theory
• Topics in Effective Field Theory for Lattice QCD