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1、TheNeutrinoRevolution(1998–…)Neutrinoshavenonzeromasses!Leptonsmix!1Thesediscoveriescomefromtheobservationofneutrinooscillation.2ThePhysicsofNeutrinoOscillation3NeutrinosComeinatLeastThreeFlavorsTheknownneutrinoflavors:e,,Eachoftheseisassociatedwiththecorrespon
2、dingcharged-leptonflavor:e,,4TheMeaningofthisAssociationeDetectoreeWbosonShortJourneyeWW5Overshortdistances,neutrinosdonotchangeflavor.WShortJourneyDoesNotOccurButifneutrinoshavemasses,andleptonsmix,neutrinoflavorchangesdooccurduringlongjourney
3、s.6LetUsAssumeNeutrinoMassesandLeptonicMixingNeutrinomass—Thereissomespectrumof3ormoreneutrinomasseigenstatesi:(Mass)21234Mass(i)mi7Leptonicmixing—WhenW+l++,theproducedneutrinostate
4、>is
5、>=U*i
6、i>.NeutrinoofflavorNeutrinoofdefinitemassmiLeptonicMixin
7、gMatrixlee,l,le,,ori8AnotherwaytolookatWdecay:Agivenl+canbeaccompaniedbyanyi.Amp(W+l++i)=U*iis
8、>=U*i
9、i>.Theneutrinostate
10、>producedtogetherwithl+i9AccordingtotheStandardModel,extendedtoincludeneutrinomassandleptonicmixing—Thenumberofdifferentiis
11、thesameasthenumberofdifferentl.ThemixingmatrixUis3x3andunitary:UU†=U†U=1.Somemodelsinclude“sterile”neutrinos—neutrinosthatexperiencenoneoftheknownforcesofnatureexceptgravity.Insuchmodels,thereareN>3i,andUisNxN,butstillunitary.10Justaseachneutrinoofdefinitefl
12、avorisasuperpositionofmasseigenstatesi,soeachmasseigenstateisasuperpositionofflavors.From
13、>=iU*i
14、i>andtheunitarityofU,
15、i>=Ui
16、>.Theflavor-fractionofiis—
17、<
18、i>
19、2=
20、Ui
21、2.11TheStandardModel(SM)descriptionofneutrinointeractions(notmassesorleptonicmixing)
22、iswell-confirmed.Wewillassumeitistrue,andextendittoincludemixing.FortheleptoncouplingstotheWboson,wethenhave—Left-handedTakingmixingintoaccount12InsertExplanationofNeutrinoOscillation13ExperimentalEvidence14EvidenceForFlavorChangeNeutrinosSolarReactor(L~180km)Atmosph
23、ericAccelerator(L=250and735km)Stopped+DecayLSNDL30mEvidenceofFlavorChangeCompellingCompellingCompellingCompellingUnconf