Partial flavor symmetry restoration for chiral staggered fermions

Weonjong Lee and Stephen R. Sharpe
Phys. Rev. D 60, 114503 – Published 1 November 1999
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Abstract

We study the leading discretization errors for staggered fermions by first constructing the continuum effective Lagrangian, including terms of O(a2), and then constructing the corresponding effective chiral Lagrangian. The terms of O(a2) in the continuum effective Lagrangian completely break the SU(4) flavor symmetry down to the discrete subgroup respected by the lattice theory. We find, however, that the O(a2) terms in the potential of the chiral Lagrangian maintain an SO(4) subgroup of SU(4). It follows that the leading discretization errors in the pion masses are SO(4) symmetric, implying three degeneracies within the seven lattice irreducible representations. These predictions hold also for perturbatively improved versions of the action. These degeneracies are observed, to a surprising degree of accuracy, in existing data. We argue that the SO(4) symmetry does not extend to the masses and interactions of other hadrons (vector mesons, baryons, etc.) or to higher order in a2. We show how it is possible that, for physical quark masses of O(a2), the new SO(4) symmetry can be spontaneously broken, leading to a staggered analogue of the Aoki phase of Wilson fermions. This does not, however, appear to happen for presently studied versions of the staggered action.

  • Received 19 May 1999

DOI:https://doi.org/10.1103/PhysRevD.60.114503

©1999 American Physical Society

Authors & Affiliations

Weonjong Lee*

  • Los Alamos National Laboratory, Mail Stop B-285, Los Alamos, New Mexico 87545

Stephen R. Sharpe

  • Physics Department, Box 351560, University of Washington, Seattle, Washington 98195-1560
  • Center for Computational Physics, University of Tsukuba, Tsukuba, Ibaraki, 305-8577, Japan

  • *Email address: wlee@lanl.gov
  • Email address: sharpe@phys.washington.edu

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Issue

Vol. 60, Iss. 11 — 1 December 1999

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