Lattice extraction of K ---> pi pi amplitudes to NLO in partially quenched and in full chiral perturbation theory

Jun, 2003
40 pages
Published in:
  • Phys.Rev.D 71 (2005) 014021
e-Print:
Report number:
  • BNL-HET-03-13

Citations per year

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Abstract:
We show that it is possible to construct ϵ/ϵ\epsilon^\prime/\epsilon to NLO using partially quenched chiral perturbation theory (PQChPT) from amplitudes that are computable on the lattice. We demonstrate that none of the needed amplitudes require three-momentum on the lattice for either the full theory or the partially quenched theory: non-degenerate quark masses suffice. Furthermore, we find that the electro-weak penguin (ΔI=3/2\Delta I=3/2 and 1/2) contributions to ϵ/ϵ\epsilon^\prime/\epsilon in PQChPT can be determined to NLO using only degenerate (mK=mπm_K=m_\pi) KπK\to\pi computations without momentum insertion. Issues pertaining to power divergent contributions, originating from mixing with lower dimensional operators, are addressed. Direct calculations of KππK\to\pi\pi at unphysical kinematics are plagued with enhanced finite volume effects in the (partially) quenched theory, but in simulations when the sea quark mass is equal to the up and down quark mass the enhanced finite volume effects vanish to NLO in PQChPT. In embedding the QCD penguin left-right operator onto PQChPT an ambiguity arises, as first emphasized by Golterman and Pallante. With one version (the PQS) of the QCD penguin, the inputs needed from the lattice for constructing KππK\to\pi\pi at NLO in PQChPT coincide with those needed for the full theory. Explicit expressions for the finite logarithms emerging from our NLO analysis to the above amplitudes are also given.
  • 12.38.Gc
  • 12.39.Fe
  • fermion: lattice field theory
  • quantum chromodynamics
  • perturbation theory: chiral
  • approximation: quenching
  • K: hadronic decay
  • amplitude analysis: decay
  • CP: violation
  • quark: mass