1 Lattice QCD: placing a hadron in a computer Introduction Current focus: dynamical Nf=2+1 simulation Nucleon structure functions Future perspectives Summary Akira Ukawa Center for Computational Sciences University of Tsukuba Nikko Symposium “Creation and development of matter” 6 November, 2004
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Lattice QCD - KEK...5 Development of lattice QCD simulations (I) size ≈2×10−15 m lattice size lattice spacing L= 0.8 fm a = 0.1 fm 1981 First lattice QCD simulation VAX speed
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Lattice QCD:placing a hadron in a computer
Introduction
Current focus: dynamical Nf=2+1 simulation
Nucleon structure functions
Future perspectives
Summary
Akira UkawaCenter for Computational SciencesUniversity of Tsukuba
Nikko Symposium“Creation and development of matter”6 November, 2004
2
Introduction
3
Quantum Chromodynamics
Quantum Chromodynamics (QCD)Fundamental theory of quarks and gluons and their strong interactions
Knowing
1 coupling constant and
6 quark masses
will allow full understanding of strong interactions “Yukawa’s dream(1935) in modern form”
tbcsdu
s
mmmmmm ,,,,,α
( ) ( )( )
( ) ( ) S
ffff
sQCD
eAOddAdZ
AO
miAFFTrS
−∫
∑
=
+−∂⋅+=
ψψψψψψ
ψγψπα µµµµνµν
,,1,,
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Gross-Wilczek-Politzer 1973
4
QCD on a Lattice
Lattice QCDPowerful mean to calculate the QCD Feyman path integral
From computational point of viewRelatively simple calculation
Uniform meshSingle scale
Requires much computing power due to
4-dim. ProblemFermions essentialPhysics is at lattice spacing a=0
International Research Network for Computational Particle Physics
UK core institution:University of Edinburgh
Dept. of PhysicsEPCC
Germany core institution:
DESYVon Neumann
Inst.for computing
USA core institution:Fermi National Accelerator
Laboratory(FNAL)
Japan core institution:
University of Tsukuba
Center for Computational
Sciences
SciDACNetworkin USA
Edinburgh
GlasgowLiverpool
Southampton
Swansea DESY/NeumannBerlin/Zeuthen
BielefeldRegensburg LatFor
Networkin Germany
KEK
Hiroshima U
LFT ForumNetworkin Japan
Future expansion to EU NetworkItaly, France, Spain, Denmark,…
Main supercomputer sites
International Lattice Data Grid (ILDG)database of QCD gluon configurations at major supercomputer facilities acceleration of research via mutual usage of QCD gluon configurations via fast internetfuture international sharing of supercomputingand data storage resources
Future expansion to Asia/Oceania
Kyoto U
UKQCDNetworkin United Kingdom
U. Tsukuba
FNAL
Washinghon U
UCSB
MIT/Boston U
BNL/Columbia
JLAB
Arizona
Utah
Indiana
St.Louise
JSPS core-to-core program
QCDOC x 2
QCDOC
APENEXT
CP-PACS II
KEK supercomputer
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Summary
Definitive prospect toward exact QCD predictions with realistic quark spectrum over the next few years
Firm numbers to our phenomenology/experiment colleaguesQuantitative understanding of the full range of strong interactions
1935 meson theory (Yukawa)1951 strangeness (Gell-Mann-Nishijima) 1961 chiral symmetry and pion(Nambu-Jona-Lasinio)1973 QCD and asymptotic freedom(Gross-Wilczek-Politzer)1974 Lattice QCD(Wilson)1981 Monte Carlo simulation of QCD(Creutz-Jacobs-Rebbi)
Lattice QCD: a prototype of computational research in which theory and instrument making go hand in hand.