量子场论引言

《量子场论引言》由会员上传分享，免费在线阅读，更多相关内容在行业资料-天天文库。

1、量子场论初步引言张宏浩1WhyQuantumFieldTheory?Quantumfieldtheoryaroseoutofourneedtodescribetheephemeralnatureoflife?No,seriously,•QuantumFieldtheoryisneededwhenweconfrontsimultaneouslythetwogreatphysicsinnovationsofthelastcenturyofthepreviousmillennium:specialrelativityandquantummechanics.•Conside

2、rafastmovingrocketshipclosetolightspeed.Youneedspecialrelativitybutnotquantummechanicstostudyitsmotion.•Ontheotherhand,tostudyaslowmovingelectronscatteringonaproton,youmustinvokequantummechanics,butyoudon’thavetoknowathingaboutspecialrelativity.•However,tounderstandprocessesthatoccurat

3、verysmall(quantum-mechanical)scalesandverylarge(relativistic)energies,oneneedsthedevelopmentofanewsubjectinphysics,thatofquantumfieldtheory.即:极小尺度(量子力学)•量子场论极大能量(狭义相对论)•Whycan’twejustquantizerelativisticparticlesthewaywequantizednonrelativisticparticles?Problems&difficulties•Negative-e

4、nergystates&otherinconsistencise•Creation/annihilationofparticle-antiparticlepairs,changeofparticlenumber,…•Virtualparticlesexistforaveryshorttime(fromuncertaintyprinciple)•Violationofmicroscopiccausality(tobediscussedlaterindetail)WhoneedsQFT?•Quantumfieldtheoryisabsolutelyessentialfo

5、runderstandingthecurrentstateofelementaryparticlephysics.•Withsomemodification,themethodofQFTalsoplaysacrucialroleinthemostactiveareasofatomic,nuclear,andcondensed-matterphysics.•Oneofthegreatadvancesintheoreticalphysicsinthelast30yearsorsoistheincreasinglysophisticateduseofquantumfiel

6、dtheoryincondensedmatterphysics.Tosummarize,•QFTwasbornofthenecessityofdealingwiththemarriageofspecialrelativityandquantummechanics,•justasthenewscienceofstringtheoryisbeingbornofthenecessityofdealingwiththemarriageofgeneralrelativityandquantummechanics.