S-parameter and pseudo-Nambu-Goldstone boson mass from lattice QCD

Abstract

We present a lattice calculation of $L_{10}$, one of the low energy constants in Chiral Perturbation Theory, and the charged-neutral pion squared mass splitting, using dynamical overlap fermion. Exact chiral symmetry of the overlap fermion allows us to reliably extract these quantities from the difference of the vacuum polarization functions for vector and axial-vector currents. In the context of the technicolor models, these two quantities are read as the $S$-parameter and the pseudo-Nambu-Goldstone boson mass respectively, and play an important role in discriminating the models from others. This calculation can serve as a feasibility study of the lattice techniques for more general technicolor gauge theories.

9 pages, 3 figures, references added, minor corrections made, version to appear in PRL

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• Finite volume QCD at fixed topological charge
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• Two-flavor lattice QCD simulation in the epsilon-regime with exact chiral symmetry
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Cited by in corpus (1)

• From hadronic tau decays to the chiral couplings L_10 and C_87