格點(diǎn)量子色動力學(xué)進(jìn)展

OnbehalfofCLQCDCollaborationChen,Y.(陳瑩)中科院高能所Liu,C.(劉川)北京大學(xué)物理學(xué)院Liu,Y.-B.(劉玉斌)南開大學(xué)物理學(xué)院Ma,J.-P.(馬建平)中科院理論物理所Zhang,J.-B.(張劍波)浙江大學(xué)物理系Students:牛志元、郭寶仲、杜德川、劉航、荔寧（北大）張遠(yuǎn)江、李剛（高能所）孟祥飛（南開）提綱國際上格點(diǎn)量子色動力學(xué)進(jìn)展generalstatuslighthadronspectrummatrixelementdecayconstants中國格點(diǎn)合作組的工作HadroninteractionFinitetemperatureglueballs總結(jié)與展望國際格點(diǎn)量子色動力學(xué)進(jìn)展大趨勢LatticeQCDisintheprocessofa“phasetransition/crossover”“quench”

→

“unquench”“awayfromphysical”

→“closetophysical”Morephysicalquantities…Errorsarebettercontrolled(bothsystematicandstatistical)Thebeastcalled“QUENCH”QuenchBeastRBCMILCPACS_CSETMCLHPCBMWJLQCDUnquenching…Domainwallfermions(RBC/UKQCD/LHPC)Overlapfermions(JLQCD)HISQ(staggered)fermions(MILC)Twistedmassfermions(ETMC)Anisotropicclover(LHPC)ImprovedWilson(BMW,NPLQCD…)Wilsonatphysicalparameters(PACS-CS)……ILDG(InternationalLatticeDataGrid)TheBerlinwall&latticeQCDK.Jansen,hep-lat/0311039Berlinwallcrushing…Morephysical…Pionmass700MeVbelow300MeVwherecPTstartstowork…evendowntophysicalvalue140MeVLatticespacingbelow0.1fmCombinedwithimprovedactionsVolumesizeafewfmDisconnectdiagrams…Afewexamples…Lighthadronspectrum

by

BMWBMW,[hep-lat]0906.3599Science322:1224-1227,2008

Lighthadronspectrum輕強(qiáng)子譜一直是格點(diǎn)量子色動力學(xué)重要應(yīng)用之一計算的原理在正確的規(guī)范場組態(tài)下平均HighlightsUnquenched(2+1flavorlatticeQCD)Completespectrum(flavornon-singletmesonsandoctet,decupletbaryons)Finitevolumecorrections(resonances)Controlledchiralextrapolation(pionmassdowntoabout200MeV)ControlledcontinuumextrapolationQuenchvs.unquenchCP_PACS,hep-lat/0206009BMW,[hep-lat]0906.3599Science322:1224-1227,2008

Chiralextrapolation(BMW)Matrixelements

Plenarytalk,Lattice2009byLubicz&vandeWaterB_K的計算RenormalizationdilemmaContinuumperturbationdoneintheMS-barNaiveDimensionalRegularizationscheme(MS-barNDR-scheme)NeedRegularizationIndependentscheme(RI/MOM-scheme)RelationbetweenoperatorsintheRI/MOM-schemeandMS-barNDR-schemeNon-perturbativematchingofoperatorsinthematchingwindowSee,plenarytalkonLattice2009byLubiczThefDspuzzle?Plenarytalk,Lattice2009byAubinExperimentalresultsComparisonIndependentdeterminationofVcsMorecomparisons…Isisapuzzle?只有HPQCD的結(jié)果偏離最嚴(yán)重Vcs需要單獨(dú)確定目前還不是很嚴(yán)重的問題…更多內(nèi)容敬請關(guān)注

Lattice2009主頁/workshop/lattice09/index.xml中國格點(diǎn)合作組的工作利用強(qiáng)子散射研究譜學(xué)許多新的強(qiáng)子態(tài)接近兩個強(qiáng)子的閾束縛態(tài)？共振態(tài)？僅僅計算簡單的關(guān)聯(lián)函數(shù)無法確定需要研究強(qiáng)子－強(qiáng)子散射相移

散射與

Z(4430)Z(4430)的實(shí)驗(yàn)發(fā)現(xiàn)接近

質(zhì)量閾值Q=+1,JP=0-,1-,2-M=4433MeVG=45MeV理論方面的探討相關(guān)的唯象理論工作ShallowboundstateoftwoDmesons(S.L.Zhuetal,PRD77,034003)Tetra-quarkresonanceabovethreshold(X.-HLiuetal,PRD77,094005)Thresholdenhancement(J.L.

Rosner,PRD76,114002)需要研究閾附近的

散射散射長度a0有效力程r0格點(diǎn)QCD提供了從第一性原理出發(fā)的、非微擾的研究方法Phys.Rev.D80:034503,2009

理論框架－有限體積方法有限體積中相互作用的兩個粒子相互作用：相對于自由粒子能量偏移相互作用：

無窮空間散射相移Luescher公式：基本公式AboxofsizeL,periodicinallthreespatialdirections:Twointeractinghadrons強(qiáng)子算符的構(gòu)造（單粒子）SingleparticleoperatorsAngularmomentumdecompositionD*+D10強(qiáng)子算符的構(gòu)造（兩粒子）散射信息的獲取Scatteringlengtha0

&

effectiveranger0各種外推Afteralltheextrapolations分析與討論P(yáng)ossibleboundstate?Boundstate:分析與討論P(yáng)ossibleboundstate?Forshallowboundstate,ButourscatteringlengthsareallpositiveOnthevergeofdevelopingaboundstateUsingthesquarewellpotentialmodeltoestimate,thepotentialwellisV0=70(10)MeV,R=0.7fm.Ourresultsisnotinfavorofashallowboundstate基本結(jié)論我們利用（quenched）格點(diǎn)QCD

研究了JP=0–

道的散射，得到了散射長度a0和有效力程r0。研究表明：在JP=0–

道，兩個粲介子具有吸引相互作用，但不太可能形成淺束縛態(tài)。Unquenched研究正在展開…其他相關(guān)的工作如何在格點(diǎn)計算中區(qū)分單粒子態(tài)與多粒子散射態(tài)？利用spectralweight?見牛志元同學(xué)明天的分會報告QCD相變中的膠球譜MotivationSignatureofQGPsQGP:glueballmaynotbehaveasonenaivelyexpects.N.Ishiietal,PRD66094506(2002)Phys.Rev.D80:114502,2009.有限溫度場論溫度變?yōu)樘摃r方向：虛時方向場具有周期/反周期邊條件有限溫關(guān)聯(lián)函數(shù)：可連續(xù)調(diào)節(jié)ThermalcorrelatorsUsingglueballoperators

f(t)SpectralfunctionBreit-Wigneransatz將d-函數(shù)換為Lorentzian:膠球極點(diǎn)質(zhì)量隨溫度變化Breit-Wignerparameterw0Breit-WignerparameterG基本結(jié)論當(dāng)溫度在[0.3Tc,2Tc]中變化過程中：極點(diǎn)質(zhì)量MG

變化緩慢BW分析中的極點(diǎn)質(zhì)量

w0

幾乎不變BW分析中的熱寬度G變化顯著：在臨界溫度下幾乎為零，臨界溫度以上迅速增加

其他正在進(jìn)行的工作Unquench(twistedmassqua