arXiv subjects

R. Burkhalter

Publications and source records attributed to R. Burkhalter.

65 records · Page 4Linked to original sources

arXiv1999

Quenched Light Hadron Spectrum

We present results of a large-scale simulation for the flavor non-singlet light hadron spectrum in quenched lattice QCD with the Wilson quark action. Hadron masses are calculated at four values of lattice spacing in the range $a \approx$ 0.1 - 0.05 fm on lattices with a physical extent of 3 fm at five quark masses corresponding to $m_π/m_ρ\approx 0.75$ - 0.4. The calculated spectrum in the continuum limit shows a systematic deviation from experiment, though the magnitude of deviation is contained within 11%. Results for decay constants and light quark masses are also reported.

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arXiv1999

Comparative Study of full QCD Hadron Spectrum and Static Quark Potential with Improved Actions

We investigate effects of action improvement on the light hadron spectrum and the static quark potential in two-flavor QCD for $a^{-1} \approx 1$ GeV and $m_{PS}/m_V = 0.7-0.9$. We compare a renormalization group improved action with the plaquette action for gluons, and the SW-clover action with the Wilson action for quarks. We find a significant improvement in the hadron spectrum by improving the quark action, while the gluon improvement is crucial for a rotationally invariant static potential. We also explore the region of light quark masses corresponding to $m_{PS}/m_V \geq 0.4$ on a 2.7 fm lattice using the improved gauge and quark action. A flattening of the potential is not observed up to 2 fm.

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arXiv1998

Recent Results from the CP-PACS Collaboration

We present an overview of recent results from the CP-PACS computer on the quenched light hadron spectrum and an on-going two-flavour full QCD study. We find that our quenched hadron mass results are compatible with the mass formulae predicted by quenched chiral perturbation theory, which we adopt in our final analysis. Quenched hadron masses in the continuum limit show unambiguous and systematic deviations from experiment. For our two-flavour full QCD simulation we present preliminary results on the light hadron spectrum, quark masses and the static potential. The question of dynamical sea quark effects in these quantities is discussed.

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arXiv1998

The static quark potential in full QCD

We report results on the static quark potential in two-flavor full QCD. The calculation is performed for three values of lattice spacing $a^{-1}\approx 0.9, 1.3$ and 2.5 GeV on $12^3{\times}24, 16^3{\times}32$ and $24^3{\times}48$ lattices respectively, at sea quark masses corresponding to $m_π/m_ρ\approx 0.8-0.6$. An RG-improved gauge action and a tadpole-improved SW clover quark action are employed. We discuss scaling of $m_ρ/\sqrtσ$ and effects of dynamical quarks on the potential.

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arXiv1998

Quenched Light Hadron Spectrum with the Wilson Quark Action: Final Results from CP-PACS

We report the final results of the CP-PACS calculation for the quenched light hadron spectrum with the Wilson quark action. Our data support the presence of quenched chiral singularities, and this motivates us to use mass formulae based on quenched chiral perturbation theory in order to extrapolate hadron masses to the physical point. Hadron masses and decay constants in the continuum limit show unambiguous systematic deviations from experiment. We also report the results for light quark masses.

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arXiv1998

Full QCD light hadron spectrum from the CP-PACS

We report on an on-going two-flavor full QCD study on CP-PACS using an RG-improved gauge action and a tadpole-improved SW quark action. Runs are made for three lattice spacings $a^{-1}\approx 0.9$, 1.3, and 2.5 GeV on $12^3\times24$, $16^3\times32$, and $24^3\times48$ lattices. Four sea quark masses having $m_{\rm PS}/m_{\rm V} \approx 0.8$--0.6 are simulated, for each of which hadron masses are evaluated for valence quark masses corresponding to $m_{\rm PS}/m_{\rm V} \approx 0.8$--0.5. Results for hadron and light quark masses are presented and compared with those obtained in quenched QCD.

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arXiv1997

Hadron spectroscopy and static quark potential in full QCD: A comparison of improved actions on the CP-PACS

We present first results from a full QCD calculation on the CP-PACS, comparing various actions at $a^{-1} \sim 1 GeV$ and $m_π/m_ρ\approx 0.7$--0.9. We use the plaquette and a renormalization group improved action for the gluons, and the Wilson and the SW-Clover action for quarks. We find that significant improvements in the hadron spectrum results from improving the quarks, while the gluon improvement is required for a rotationally invariant static potential. An ongoing effort towards exploring the chiral limit in full QCD is described.

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arXiv1997

CP-PACS results for quenched QCD spectrum with the Wilson action

We present progress report of a CP-PACS calculation of quenched QCD spectrum with the Wilson quark action. Light hadron masses and meson decay constants are obtained at $β=$5.9, 6.1, and 6.25 on lattices with a physical extent of 3 fm, and for the range of quark mass corresponding to $m_π/m_ρ\approx 0.75$ $-$ 0.4. Nucleon mass at each $β$ appears to be a convex function of quark mass, and consequently the value at the physical quark mass is much smaller than previously thought. Hadron masses extrapolated to the continuum limit exhibits a significant deviation from experimental values: with $K$ meson mass to fix strange quark mass, strange meson and baryon masses are systematically lower. Light quark masses determined from the axial Ward identity are shown to agree with those from perturbation theory in the continuum limit. Decay constants of mesons are also discussed.

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arXiv1997

CP-PACS Result for the Quenched Light Hadron Spectrum

The quenched hadron spectrum in the continuum obtained with the Wilson quark action in recent simulations on the CP-PACS is presented. Results for the light quark masses and the QCD scale parameter are reported.

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arXiv1997

Full QCD simulation on CP-PACS

A status report is made of an on-going full QCD study on the CP-PACS aiming at a comparative analysis of the effects of improving gauge and quark actions on hadronic quantities and static quark potential. Simulations are made for four action combinations, the plaquette or an RG-improved action for gluons and the Wilson or SW-clover action for quarks, at $a^{-1} \approx 1.1$-1.3GeV and $m_π/m_ρ\approx 0.7$-0.9. Results demonstrate clearly that the clover term markedly reduces discretization errors for hadron spectrum, while adding six-link terms to the plaquette action leads to much better rotational symmetry in the potential. These results extend experience with quenched simulations to full QCD.

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arXiv1994

Perfect topological charge for asymptotically free theories

The classical equations of motion of the perfect lattice action in asymptotically free $d=2$ spin and $d=4$ gauge models possess scale invariant instanton solutions. This property allows the definition of a topological charge on the lattice which is perfect in the sense that no topological defects exist. The basic construction is illustrated in the $d=2$ O(3) non--linear $σ$--model and the topological susceptibility is measured to high precision in the range of correlation lengths $ξ\in (2 - 60)$. Our results strongly suggest that the topological susceptibility is not a physical quantity in this model.

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