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Determination of the $Delta S = 1$ weak Hamiltonian in the SU(4) chiral limit through topological zero-mode wave functions

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 Added by Pilar Hernandez
 Publication date 2008
  fields
and research's language is English




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A new method to determine the low-energy couplings of the $Delta S=1$ weak Hamiltonian is presented. It relies on a matching of the topological poles in $1/m^2$ of three-point correlators of two pseudoscalar densities and a four-fermion operator, measured in lattice QCD, to the same observables computed in the $epsilon$-regime of chiral perturbation theory. We test this method in a theory with a light charm quark, i.e. with an SU(4) flavour symmetry. Quenched numerical measurements are performed in a 2 fm box, and chiral perturbation theory predictions are worked out up to next-to-leading order. The matching of the two sides allows to determine the weak low-energy couplings in the SU(4) limit. We compare the results with a previous determination, based on three-point correlators containing two left-handed currents, and discuss the merits and drawbacks of the two procedures.



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488 - P. Hernandez , M. Laine , C. Pena 2007
We discuss a new method to determine the low-energy couplings of the $Delta S=1$ weak Hamiltonian in the $epsilon$-regime. It relies on a matching of the topological poles in $1/m^2$ of three-point functions of two pseudoscalar densities and a four-fermion operator computed in lattice QCD, to the same observables in the Chiral Effective Theory. We present the results of a NLO computation in chiral perturbation theory of these correlation functions together with some preliminary numerical results.
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