悼念羅向前教授PPT課件

1、悼念羅向前教授Back to physics 目前形勢和我們的任務 近年格點QCD進展北京大學物理學院理論物理所北京大學物理學院理論物理所劉川劉川Outlineo格點QCD簡介nWhat, Why & Howo國際上的進展nChiralnQuenchingnFinite densitynHeavy quarknBroad resonancen.o我國格點QCD的情況n參加的人員n已經完成的工作n正在進行的工作n計算資源o總結與展望格點格點QCD簡介簡介What is lattice QCDoQCD的場變量定義在四維格點上n物質場定義在site上n規(guī)范場定義在link上o格點提供了自然的

2、紫外、紅外截斷,exp,USDUDDZUMUSUSUSUSLQCDyxyyxxffgLQCD規(guī)范場部分規(guī)范場部分夸克場夸克場部分部分Why lattice QCDo強相互作用的非微擾特性強相互作用的非微擾特性o格點格點QCD是系統(tǒng)處理是系統(tǒng)處理QCD非微非微擾性質的理論方法擾性質的理論方法n非微擾的定義（非微擾的定義（path integral）n非微擾的計算（非微擾的計算（Monte Carlo）How to do lattice QCDoMonte Carlo simulationsdetexp,expUMUSDUUSDUDDZgLQCD視為概率密度視為概率密度Quench:略去略去det

3、格點格點QCD近年進展近年進展格點QCD的幾個困難問題oChiralityoQuenched vs. unquenchedoFinite density oHeavy quarkoBroad resonanceoAll boils down tonot enough computers!The trouble of being chiraloChiral symmetry is crucial for QCDoNielsen-Ninomiya (no-go) theoremnLocalitynHermitiannCorrect low-momentum limitnChiral: nNO fe

4、rmion matrix D can satisfy all of the above 4 conditions0,5DChirality Becomes More Complicated on LatticesoChiral properties of LQCD depend onnThe type of lattice fermion being usednQuenched or unquenchedVariants of lattice fermionsoWilson fermionnImproved WilsonoStaggered (Kogut-Susskind) fermionnI

5、mproved StaggeredoDomain wall fermionoOverlap fermion Chiral fermions on the latticeoChiral extrapolation (practical problem)nAll lattice simulations (quenched or unquenched) are performed at a quark mass value higher than that of physical u&d quarks.nAll lattice QCD calculations involving light

6、 quarks need chiral extrapolationoChiral fermions (more fundamental problem)nHow to put chiral fermions on the latticenHow to define chiral gauge theory non-perturbatively, etc.Quenched vs. unquenchedoQuenchednIgnore (apart from trivial renormalization effects) internal quark loopsnGauge field conf.

7、 generated via pure gaugeoPartially quenchednGauge field conf. generated at some sea quark mass valuesnValance quark mass NOT equal to sea quark massoUnquenchednJust dont quench!Unquenched conf.s on the market (incomplete)oMILC conf.s:nSymanzik improved gaugen(2+1) flavor improved staggered (AsqTad)

8、oCP-PACS/JLQCD conf.s:nRG improved gaugen(2+1) flavor Clover quarkoRBC & UKQCD conf.s:nDBW2 improved gaugen2 flavor domain wall fermionRunning parametersComparisons Name Current statusWilsonoSimpleowell-definedoNo chiral symm.ounquenching costlyrunning unquenchedStaggeredoSimpleoPartial chiral s

9、ymm.oUnquenching not so costlyoTaste does NOT taste good!running unquenchedDW/OverlapchiralcostlyMostly quenchedFinite densityoReweightingoTaylor expansionoCanonical ensembleSee: Lattice QCD at Finite DensityChristian SchmidtPoS (LAT2006) 021 hep-lat/0610116What about heavy quarksoMass heavy, ma not

10、 much less than 1oNeed improved actionoBetter use anisotropic latticeoMost difficult is heavy+light systemoMaybe DWF/overlap will help?Fat resonanceso格點計算中通常的譜計算給出哈密頓量的本征值o對于穩(wěn)定的（或者足夠苗條的）強子，格點計算的數(shù)值與強子的pole mass接近o寬共振怎么辦？Some randomly (or not so randomly) selected resultsGold-plated quantitiesQuark ma

11、ssesQuenched light hadron spectrumUnquenched results2+1 flavor light hadron spectrum and quark masses with the $O(a)$ improved Wilson-clover quark formalismCP-PACS & JLQCD , PoS(LAT2006)181, hep-lat/0610050非純學術方面的進展o對計算資源投入的加大n資金的投入n機器的更新o合作組的形成o格點資源的共享與交流我國格點我國格點QCD的現(xiàn)狀的現(xiàn)狀看來，咱看來，咱也得搞互也得搞互助組啊！助組啊

12、！嗯那，以嗯那，以后還有初后還有初級社、高級社、高級社、級社、China Lattice QCD Collaboration (CLQCD)Faculty Members:Jian-Ping Ma ITP, CASChuan Liu Peking UniversityXiang-Qian Luo Zhongshan UniversityYubin Liu Nankai UniversityJianbo Zhang Zhejiang UniversityYing Chen IHEP, CASGraduate Students (not complete):Ming Gong, Xin Li, G

13、uozhan Meng, Ji-Yuan Niu, Xu Feng, Song He(PKU), Xiang-Fei Meng (NKU), Gang Li, Yuan-Jiang Zhang (IHEP) , etc.已經完成的一些工作o膠球譜o粲物理和其他強子譜o強子強子相互作用oOverlap fermiono不對稱格點上的 DWF/Overlap（主要應用于含有粲夸克強子）o有限溫度、有限密度glueballoGlueball Spectrum and Matrix Elements on Anisotropic LatticesY. Chen, A. Alexandru, S.J.

14、Dong, T. Draper, I. Horvath, F.X. Lee, K.F. Liu, N. Mathur, C. Morningstar, M. Peardon, S. Tamhankar, B.L. Young, J.B. Zhang Phys.Rev. D73 (2006) 014516, hep-lat/0510074 oMonte Carlo study of glueball masses in the Hamiltonian limit of SU(3) lattice gauge theoryAuthors: Mushtaq Loan, Xiang-Qian Luo,

15、 Zhi-Huan Luo Int.J.Mod.Phys. A21 (2006) 2905 hep-lat/0503038 oThe First Calculation for the Mass of the Ground $4+$ Glueball State on LatticeAuthors: Da Qing Liu, Ji Min Wu Mod.Phys.Lett. A17 (2002) 1419 hep-lat/0105019 oScalar and Tensor Glueballs on Asymmetric Coarse LatticesAuthors: C. Liu Nucl.

16、Phys.Proc.Suppl. 94 (2001) 255 hep-lat/0010007 oA Lattice Study of the Glueball SpectrumAuthors: Chuan Liu Chin.Phys.Lett. 18 (2001) 187 hep-lat/0004018 Finite densityoPhase structure of lattice QCD with Wilson and Neuberger quarks at finite temperature and densityXiang-Qian Luo, He-Sheng Chen, Xiao

17、-Lu Yu PoS LAT2005 (2005) 151, hep-lat/0510102 oPhase diagram of QCD at finite temperature and chemical potential from lattice simulations with dynamical Wilson quarksHe-Sheng Chen, Xiang-Qian Luo Phys.Rev. D72 (2005) 034504 hep-lat/0411023 oChiral condensate of lattice QCD with massless quarks from

18、 the probability distribution function methodXiang-Qian Luo Phys.Rev. D69 (2004) 076012 hep-lat/0409032 oTricritical point of lattice QCD with Wilson quarks at finite temperature and densityXiang-Qian Luo Phys.Rev. D70 (2004) 091504, hep-lat/0405019 oHamiltonian lattice quantum chromodynamics at fin

19、ite density with Wilson fermionsYi-Zhong Fang, Xiang-Qian Luo Phys.Rev. D69 (2004) 114501 hep-lat/0210031 oResponses of quark condensates to the chemical potentialO. Miyamura, S. Choe, Y. Liu, T. Takaishi, A. NakamuraPhys.Rev. D66 (2002) 077502, hep-lat/0204013oScreening mass responses to the chemic

20、al potential at finite temperatureS. Choe, Ph. de Forcrand, M. Garca Prez, S. Hioki, Y. Liu, H. Matsufuru, O. Miyamura, A. Nakamura, I.-O. Stamatescu, T. Takaishi, T. Umeda, Nucl.Phys.Proc.Suppl. 106 (2002) 462CharmoQuenched charmonium spectrumS. Choe, Ph. de Forcrand, M. Garcia Perez, Y. Liu, A. Na

21、kamura, I.-O. Stematescu, T. Takaishi, T. Umeda JHEP 0308 (2003) 022 hep-lat/0307004oStatic Quark Potential and the Renormalized Anisotropy on Tadpole Improved Anisotropic LatticesWei Liu, Ying Chen, Ming Gong, Xin Li, Chuan Liu, Guozhan Meng Mod.Phys.Lett. A21 (2006) 2313 hep-lat/0603015 oGluonic e

22、xcitation of non-exotic hybrid charmonium from lattice QCD Xiang-Qian Luo, Yan Liu Phys.Rev. D74 (2006) 034502; Erratum-ibid. D74 (2006) 039902 hep-lat/0512044 oEstimate of the charmed 0- hybrid meson spectrum from quenched lattice QCD Yan Liu, Xiang-Qian Luo Phys.Rev. D73 (2006) 014516 hep-lat/0511

23、015 oCharmonium Spectrum from Quenched QCD with Overlap FermionsS. Tamhankar, A. Alexandru, Y. Chen, S.J. Dong, T. Draper, I. Horvath, F.X. Lee, K.F. Liu, N. Mathur, J.B. Zhang Phys.Lett. B638 (2006) 55 hep-lat/0507027Charm & others spectrumoQuenched Charmed Meson Spectra using Tadpole Improved

24、Quark Action on Anisotropic LatticesLiuming Liu, Shiquan Su, Xin Li, Chuan Liu Chin.Phys.Lett. 22 (2005) 2198 hep-lat/0505006 oA Numerical Study of Improved Quark Actions on Anisotropic LatticesShiquan Su, Liuming Liu, Xin Li, Chuan Liu Int.J.Mod.Phys. A21 (2006) 1015, hep-lat/0412034 oA study of pe

25、ntaquarks on the lattice with overlap fermionsN. Mathur, F.X. Lee, A. Alexandru, C. Bennhold, Y. Chen, S.J. Dong, T. Draper, I. Horvath, K.F. Liu, S. Tamhankar, J.B. Zhang Phys.Rev. D70 (2004) 074508, hep-ph/0406196 oRoper Resonance and S_11(1535) from Lattice QCDN. Mathur, Y. Chen, S.J. Dong, T. Dr

26、aper, I. Horvth, F.X. Lee, K.F. Liu, J.B. Zhang Phys.Lett. B605 (2005) 137 hep-ph/0306199 Domain wall/overlapoMassive Domain Wall Fermions on Four-dimensional Anisotropic LatticesXu Feng, Xin Li, Wei Liu, Chuan Liu JHEP 0608 (2006) 060 oNonperturbative renormalization of composite operators with ove

27、rlap fermionsJ.B. Zhang, N. Mathur, S.J. Dong, T. Draper, I. Horvth, F.X. Lee, D.B.Leinweber, K.F. Liu, A.G. Williams Phys.Rev. D72 (2005) 114509 hep-lat/0507022 oThe Negativity of the Overlap-Based Topological Charge Density Correlator in Pure-Glue QCD and the Non-Integrable Nature of its Contact P

28、artI. Horvath, A. Alexandru, J.B. Zhang, Y. Chen, S.J. Dong, T. Draper, K.F. Liu, N. Mathur, S. Tamhankar, H.B. Thacker Phys.Lett. B617 (2005) 49 hep-lat/0504005 oInherently Global Nature of Topological Charge Fluctuations in QCDI. Horvath, A. Alexandru, J.B. Zhang, Y. Chen, S.J. Dong, T. Draper, F.

29、X. Lee, K.F. Liu, N. Mathur, S. Tamhankar, H.B. Thacker Phys.Lett. B612 (2005) 21 hep-lat/0501025 oChiral Logs in Quenched QCDY. Chen, S.J. Dong, T. Draper, I. Horvth, F.X. Lee, K.F. Liu, N. Mathur, J.B. Zhang Phys.Rev. D70 (2004) 034502 hep-lat/0304005 oLow-Dimensional Long-Range Topological Charge

30、 Structure in the QCD VacuumI. Horvath, S.J. Dong, T. Draper, F.X. Lee, K.F. Liu, N. Mathur, H.B. Thacker, J.B. Zhang Phys.Rev. D68 (2003) 114505 hep-lat/0302009 oChiral Properties of Pseudoscalar Mesons on a Quenched $204$ Lattice with Overlap FermionsS.J. Dong, T. Draper, I. Horvath, F.X. Lee, K.F

31、. Liu, J.B. Zhang Phys.Rev. D65 (2002) 054507 hep-lat/0108020 Hadron-hadron scatteringoTwo Particle States in a Box and the $s$-Matrix in Multi-Channel ScatteringChuan Liu, Xu Feng, Song He Int.J.Mod.Phys. A21 (2006) 847 hep-lat/0508022 oTwo Particle States and the $S$-matrix Elements in Multi-chann

32、el ScatteringSong He, Xu Feng, Chuan Liu JHEP 0507 (2005) 011 hep-lat/0504019 oI=2 Pion scattering length with improved actions on anisotropic latticesXining Du, Guangwei Meng, Chuan Miao, Chuan Liu Int.J.Mod.Phys. A19 (2004) 5609 hep-lat/0404017 oTwo Particle States in an Asymmetric Box and the Ela

33、stic Scattering PhasesXu Feng, Xin Li, Chuan Liu Phys.Rev. D70 (2004) 014505 hep-lat/0404001 oLattice study on kaon pion scattering length in the $I=3/2$ channelChuan Miao, Xining Du, Guangwei Meng, Chuan Liu Phys.Lett. B595 (2004) 400 hep-lat/0403028 oTwo Particle States in an Asymmetric BoxXin Li,

34、 Chuan Liu Phys.Lett. B587 (2004) 100 hep-lat/0311035 oLattice study on kaon nucleon scattering length in the I=1 channelGuangwei Meng, Chuan Miao, Xining Du, Chuan Liu Int.J.Mod.Phys. A19 (2004) 4401 hep-lat/0309048 oCalculating the I=2 Pion Scattering Length Using Tadpole Improved Clover Wilson Ac

35、tion on Coarse Anisotropic LatticesChuan Liu, Junhua Zhang, Ying Chen, J.P. Ma Nucl.Phys. B624 (2002) 360 hep-lat/0109020 幾個正在進行的工作oCharmonium spectrum ( excited states, hybrids, etc.)oPion-pion scattering phase shiftoLattice QCD at finite temperature and finite densityoMassive DWF applied to charme

36、d hadrons Charmonia spectraoMotivation A series of heavy meson states of open-charm and closed-charm have been observed recently. Y(4260) (likely a 1-,hybrid charmonium?) X(3872) (most likely 1+, but refuses to fit into the 2P state predictions of non-relativistic quark models ). Many model-dependen

37、t theoretical interpretation of the newly observed meson states.Charmonia spectraThis figure and table on next page illustrate the results from the finest lattice. X(3872)?Summary to the charmonium spectrum study1.With SEB, the masses of the excited states can be reliably derived from charmonium two

38、-point functions.2.The masses of 2S charmonium states agrees well with experimental data. 3.The masses of 2P charmonium states obtained in this work are 3.798( 70), 3.827(50), and 3.799(60) for 0+, 1+ and 1+- states, respectively. Given 1+ for X(3872), 2P(1+) is consistent with X(3872) in mass.4.Masses of hybrid charmonia with exotic quantum numbers can be derived reliably. Howver for hybrid charmonia with non-exotic quantum numbers, it still a tough job.5.In particular, we have not observed a clear hybri