Methods of Quantization

Thisvolumecontainsthewrittenversionsofinvitedlecturespresentedat the"39. InternationaleUniversitatswochenfur .. Kern-undTeilchenphysik"in Schladming, Austria, which took place from February 26th to March 4th, 2000. The title of the school was "Methods of Quantization". This is, of course,averybroad?eld,soonlysomeofthenewandinterestingdevel- mentscouldbecoveredwithinthescopeoftheschool. About75yearsagoSchrodingerpresentedhisfamouswaveequationand Heisenbergcameupwithhisalgebraicapproachtothequantum-theoretical treatmentofatoms. Aimingmainlyatanappropriatedescriptionofatomic systems, these original developments did not take into consideration E- stein'stheoryofspecialrelativity. WiththeworkofDirac,Heisenberg,and Pauliitsoonbecameobviousthatauni?edtreatmentofrelativisticandqu- tume?ectsisachievedbymeansoflocalquantum?eldtheory,i. e. anintrinsic many-particletheory. Mostofourpresentunderstandingoftheelementary buildingblocksofmatterandtheforcesbetweenthemisbasedonthequ- tizedversionof?eldtheorieswhicharelocallysymmetricundergaugetra- formations. Nowadays,theprevailingtoolsforquantum-?eldtheoreticalc- culationsarecovariantperturbationtheoryandfunctional-integralmethods. Beingnotmanifestlycovariant,theHamiltonianapproachtoquantum-?eld theorieslagssomewhatbehind,althoughitresemblesverymuchthefamiliar nonrelativisticquantummechanicsofpointparticles. Aparticularlyintere- ingHamiltonianformulationofquantum-?eldtheoriesisobtainedbyqu- tizingthe?eldsonhypersurfacesoftheMinkowsispacewhicharetangential tothelightcone. The"timeevolution"ofthesystemisthenconsideredin + "light-conetime"x =t+z/c. Theappealingfeaturesof"light-conequ- tization",whicharethereasonsfortherenewedinterestinthisformulation ofquantum?eldtheories,werehighlightedinthelecturesofBernardBakker andThomasHeinzl. Oneoftheopenproblemsoflight-conequantizationis theissueofspontaneoussymmetrybreaking. Thiscanbetracedbacktozero modeswhich,ingeneral,aresubjecttocomplicatedconstraintequations. A generalformalismforthequantizationofphysicalsystemswithconstraints waspresentedbyJohnKlauder. Theperturbativede?nitionofquantum?eld theoriesisingenerala?ictedbysingularitieswhichareovercomebyare- larizationandrenormalizationprocedure. Structuralaspectsoftherenormal- VI Preface izationprobleminthecaseofgaugeinvariant?eldtheorieswerediscussed inthelectureofKlausSibold. Areviewofthemathematicsunderlyingthe functional-integralquantizationwasgivenbyLudwigStreit. Apartfromthetopicsincludedinthisvolumetherewerealsolectures ontheKaluza-odingerpresentedhisfamouswaveequationand Heisenbergcameupwithhisalgebraicapproachtothequantum-theoretical treatmentofatoms. Aimingmainlyatanappropriatedescriptionofatomic systems, these original developments did not take into consideration E- stein'stheoryofspecialrelativity. WiththeworkofDirac,Heisenberg,and Pauliitsoonbecameobviousthatauni?edtreatmentofrelativisticandqu- tume?ectsisachievedbymeansoflocalquantum?eldtheory,i. e. anintrinsic many-particletheory. Mostofourpresentunderstandingoftheelementary buildingblocksofmatterandtheforcesbetweenthemisbasedonthequ- tizedversionof?eldtheorieswhicharelocallysymmetricundergaugetra- formations. Nowadays,theprevailingtoolsforquantum-?eldtheoreticalc- culationsarecovariantperturbationtheoryandfunctional-integralmethods. Beingnotmanifestlycovariant,theHamiltonianapproachtoquantum-?eld theorieslagssomewhatbehind,althoughitresemblesverymuchthefamiliar nonrelativisticquantummechanicsofpointparticles. Aparticularlyintere- ingHamiltonianformulationofquantum-?eldtheoriesisobtainedbyqu- tizingthe? eldsonhypersurfacesoftheMinkowsispacewhicharetangential tothelightcone. The"timeevolution"ofthesystemisthenconsideredin + "light-conetime"x =t+z/c. Theappealingfeaturesof"light-conequ- tization",whicharethereasonsfortherenewedinterestinthisformulation ofquantum?eldtheories,werehighlightedinthelecturesofBernardBakker andThomasHeinzl. Oneoftheopenproblemsoflight-conequantizationis theissueofspontaneoussymmetrybreaking. Thiscanbetracedbackto...