Scalar meson in dynamical and partially quenched two-flavor QCD: Lattice results and chiral loops
- Department of Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana (Slovenia)
- RIKEN-BNL Research Center, Brookhaven National Laboratory, Upton, New York 11973 (United States)
- Center for Theoretical Physics, Laboratory for Nuclear Science and Department of Physics, MIT, Cambridge, Massachusetts 02139-4307 (United States)
- Physics Department, Brookhaven National Laboratory, Upton, New York 11973 (United States)
This is an exploratory study of the lightest nonsinglet scalar qq state on the lattice with two dynamical quarks. Domain wall fermions are used for both sea and valence quarks on a 16{sup 3}x32 lattice with an inverse lattice spacing of 1.7 GeV. We extract the scalar meson mass 1.58{+-}0.34 GeV from the exponential time dependence of the dynamical correlators with m{sub val}=m{sub sea} and N{sub f}=2. Since this statistical error bar from dynamical correlators is rather large, we analyze also the partially quenched lattice correlators with m{sub val}{ne}m{sub sea}. They are positive for m{sub val}{>=}m{sub sea} and negative for m{sub val}<m{sub sea}. In order to understand this striking effect of partial quenching, we derive the scalar correlator within the partially quenched chiral perturbation theory (ChPT) and find it describes lattice correlators well. The leading unphysical contribution in partially quenched ChPT comes from the exchange of the two pseudoscalar fields and is also positive for m{sub val}{>=}m{sub sea} and negative for m{sub val}<m{sub sea} at large t. After the subtraction of this unphysical contribution from the partially quenched lattice correlators, the correlators are positive and exponentially falling. The resulting scalar meson mass 1.51{+-}0.19 GeV from the partially quenched correlators is consistent with the dynamical result and has an appreciably smaller error bar.
- OSTI ID:
- 20705644
- Journal Information:
- Physical Review. D, Particles Fields, Vol. 70, Issue 9; Other Information: DOI: 10.1103/PhysRevD.70.094503; (c) 2004 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
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