A status report of the QCDSF Nf=2+1 Project

Yoshifumi Nakamura (NIC/DESY)for the QCDSF collaboration

Lattice 2007 @ RegensburgAug. 3, 2007

Introduction

QCDSF

Motivation:

QCDSF Collaboration has performed simulations of lattice QCD with 2 flavors of dynamical quarks

Real world: 6 flavors (3 light, 3 heavy) We want to deal with u, d and s quark dynamically

Expectation:

Improve:the hadron and quark massesweak matrix elementMoments of generalized distributions ・ ・ ・ ・ ・

lattice 2007

Action

QCDSF lattice 2007

Gauge: Improved gauge action

Tadpole improved Symanzik glue:

decrease O(a2) lattice discretization error

(Nf=3)HPQCD

Action

QCDSF

Fermion: Clover fermion action with stout links(FLRC)

better chiral propertiessmaller cut-off effects

Mild form of UV filtering:

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Morningstar & Peardon

Algorithm

QCDSF

Partition function

Even odd preconditioning

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Algorithm

QCDSF

Multi mass preconditioning

We modify action

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Hasenbusch

Horváth, Kennedy & Sint

Algorithm

QCDSF

Multiple time integration scheme:

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3 time scalesSexton & Weingarten

Chronological inverter by Minimal Residual Extrapolation:Brower et al., NPB484

Algorithm test

QCDSF lattice 2007

Test

QCDSF lattice 2007

Partially quenched

QCDSF lattice 2007

Partially quenched

QCDSF lattice 2007

Vector meson

QCDSF lattice 2007

Nucleon

QCDSF lattice 2007

QCDSF lattice 2007

Our 2+1 flavors action is more continuum like than our 2 flavors

Conclusion

QCDSF

QCDSF 2+1 project startedWe did good choice for action

lattice 2007

Plan:

TODO: More elaborate tests Implementing new idea

Performance: ~20% of peak @Altix 20-25% of peak @BGL

RHMC

QCDSF

optimal coefficients are found by the Remez algorithm for a given range

MC step

MD step

lattice 2007

Horváth, Kennedy & Sint