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arXiv · 1012.0987

Flavor symmetry breaking in lattice QCD with a mixed action

Oliver Bar·Maarten Golterman·Yigal Shamir
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Abstract

We study the phase structure of mixed-action QCD with two Wilson sea quarks and any number of chiral valence quarks (and ghosts), starting from the chiral lagrangian. A priori, the effective theory allows for a rich phase structure, including a phase with a condensate made of sea and valence quarks. In such a phase, mass eigenstates would become admixtures of sea and valence fields, and pure-sea correlation functions would depend on the parameters of the valence sector, in contradiction with the actual setup of mixed-action simulations. Using that the spectrum of the chiral Dirac operator has a gap for nonzero quark mass we prove that spontaneous symmetry breaking of the flavor symmetries can only occur within the sea sector. This rules out a mixed condensate, and implies restrictions on the low-energy constants of the effective theory.

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Oliver Bar, Maarten Golterman, Yigal Shamir. 2010-12-05. Flavor symmetry breaking in lattice QCD with a mixed action. https://doi.org/10.1103/physrevd.83.054501

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