Topological susceptibility in lattice QCD with two flavors of dynamical quarks

Arifa Ali Khan

Aoki Sinya

Burkhalter Rudolf

Ejiri Shinji

Fukugita Masataka

Hashimoto Shoji

Ishizuka Naruhito

Iwasaki Yoichi

Kanaya Kazuyuki

Kaneko Takashi

Kuramashi Yoshinobu

Manke Thomas

Nagai Keiichi

Okawa Masanori

Shanahan Hugh P.

Ukawa Akira

Yoshie Tomoteru

Physical review D

We present a study of the topological susceptibility in lattice QCD with two degenerate flavors of dynamical quarks. The topological charge is measured on gauge configurations generated with a renormalization group improved gauge action and a mean field improved clover quark action at three values of β=6/g2 with four sea quark masses at each β. The lattice spacings at these β's are a≈0.22, 0.16 and 0.11 fm at the physical up and down quark mass, which are fixed by the physical ρ meson mass. The study is supplemented by simulations of pure SU(3) gauge theory with the same gauge action at 5 values of β with lattice spacings 0.09 fm?a ?0.27 fm. We employ a field-theoretic definition of the topological charge together with cooling. For the topological susceptibility in the continuum limit of pure SU(3) gauge theory we obtain χt1/4= 197-16+13 MeV where the error shows statistical and systematic ones added in quadrature. In full QCD χt at heavy sea quark masses is consistent with that of pure SU(3) gauge theory. A decrease of χt toward light quark masses, as predicted by the anomalous Ward-Takahashi identity for U(1) chiral symmetry, becomes clearer for smaller lattice spacings. The cross over in the behavior of χt from heavy to light sea quark masses is discussed.

eng

American Physical Society

Copyright (c) 2001 American Physical Society.

[ISSN] 1550-7998

[DOI] 10.1103/PhysRevD.64.114501

[NCID] AA00773624

[DOI] http://dx.doi.org/10.1103/PhysRevD.64.114501