The Neutrino World：中微子的世界.ppt

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1、TheNeutrinoRevolution(1998–…)Neutrinoshavenonzeromasses!Leptonsmix!1Thesediscoveriescomefromtheobservationofneutrinooscillation.2ThePhysicsofNeutrinoOscillation3NeutrinosComeinatLeastThreeFlavorsTheknownneutrinoflavors:e,,Eachoftheseisassociatedwiththecorrespon

2、dingcharged-leptonflavor:e,,4TheMeaningofthisAssociationeDetectoreeWbosonShortJourneyeWW5Overshortdistances,neutrinosdonotchangeflavor.WShortJourneyDoesNotOccurButifneutrinoshavemasses,andleptonsmix,neutrinoflavorchangesdooccurduringlongjourney

3、s.6LetUsAssumeNeutrinoMassesandLeptonicMixingNeutrinomass—Thereissomespectrumof3ormoreneutrinomasseigenstatesi:(Mass)21234Mass(i)mi7Leptonicmixing—WhenW+l++,theproducedneutrinostate

4、>is

5、>=U*i

6、i>.NeutrinoofflavorNeutrinoofdefinitemassmiLeptonicMixin

7、gMatrixlee,l,le,,ori8AnotherwaytolookatWdecay:Agivenl+canbeaccompaniedbyanyi.Amp(W+l++i)=U*iis

8、>=U*i

9、i>.Theneutrinostate

10、>producedtogetherwithl+i9AccordingtotheStandardModel,extendedtoincludeneutrinomassandleptonicmixing—Thenumberofdifferentiis

11、thesameasthenumberofdifferentl.ThemixingmatrixUis3x3andunitary:UU†=U†U=1.Somemodelsinclude“sterile”neutrinos—neutrinosthatexperiencenoneoftheknownforcesofnatureexceptgravity.Insuchmodels,thereareN>3i,andUisNxN,butstillunitary.10Justaseachneutrinoofdefinitefl

12、avorisasuperpositionofmasseigenstatesi,soeachmasseigenstateisasuperpositionofflavors.From

13、>=iU*i

14、i>andtheunitarityofU,

15、i>=Ui

16、>.Theflavor-fractionofiis—

17、<

18、i>

19、2=

20、Ui

21、2.11TheStandardModel(SM)descriptionofneutrinointeractions(notmassesorleptonicmixing)

22、iswell-confirmed.Wewillassumeitistrue,andextendittoincludemixing.FortheleptoncouplingstotheWboson,wethenhave—Left-handedTakingmixingintoaccount12InsertExplanationofNeutrinoOscillation13ExperimentalEvidence14EvidenceForFlavorChangeNeutrinosSolarReactor(L~180km)Atmosph

23、ericAccelerator(L=250and735km)Stopped+DecayLSNDL30mEvidenceofFlavorChangeCompellingCompellingCompellingCompellingUnconf