中性微子物理(三)

NeutrinoPhysicsIIIHitoshiMurayamaTaiwanSpringSchoolMarch28,20021中性微子物理（三）村山斉臺灣春期學(xué)校二千二年三月二十八日2OutlineLSNDImplicationsofNeutrinoMassWhydoweexist?ModelsofflavorConclusions34LSND563.3sSignalExcesspositroneventsovercalculatedBG7Mini-BooNELSNDunconfirmedNeutrinobeamfromFermilabboosterSettlestheissueofLSNDevidenceStartdatatakinglaterthisyear8SN1987Aneutrinoburst

doesn’tlikeLSNDHM,YanagidaKamiokande’s11events:1steventisforward

maywellbenefromdeleptonizationburst (pe-

nnetobecomeneutronstar)LatereventsmostlikelyneLSNDparameterscausecompleteMSWconversionof

ne

nmiflightside(nelighter)

ne

nmifdarkside(neheavier)Eithermassspectrumdisfavored___9SN1987Aneutrinoburst

doesn’tlikeLSNDHM,Yanagida10SterileNeutrinoLSND,atmosphericandsolarneutrinooscillationsignals Dm2LSND~eV2 Dm2atm~3

10–3eV2 Dm2solar<10–3eV2

Can’tbeaccommodatedwith3neutrinos

NeedasterileneutrinoNewtypeofneutrinowithnoweakinteraction3+1or2+2spectrum?11SterileNeutrinogettingtight3+1spectrum:sin22qLSND=4|U4e|2|U4m|2|U4m|2can’tbebigbecauseofCDHS,SKU/D|U4e|2can’tbebigbecauseofBugeyMarginallyallowed(90%excl.vs99%allw’d)2+2spectrum:pastfitspreferredAtmosphericmostlynm

ntSolarmostlyne

ns

(orviceversa)Nowsolarsterilegettingtight(Bargeretal,Giuntietal,Gonzalez-Garciaetal,Strumia)12NotQuiteExcludedYet…Globalfittofour-neutrinooscillationSolar,Atmospheric,LSND(Gonzalez-Garcia,Maltoni,Pe?a-Garay@EPS01)Onecanstillfindareasonablefitwith2+2Disfavoredat90-99%CLne

ns

nm

ntne

nt

nm

ns13CPTViolation?

“Adesperateremedy…”LSNDevidence:

anti-neutrinosSolarevidence:

neutrinosIfneutrinosandanti-neutrinoshavedifferentmassspectra,atmos-pheric,solar,LSNDaccommodatedwithoutasterileneutrino

(HM,Yanagida)14CPTTheoremBasedonthreeassumptions:LocalityLorentzinvarianceHermiticityofHamiltonianViolationofanyoneofthem:

bigimpactonfundamentalphysicsNeutrinomass:tinyeffectfromhigh-scalephysicsNon-commutativegeometry?(HM,Yanagida)Braneworld?(Barenboim,Borissov,Lykken,Smirnov)15ImplicationsonExperimentsMini-BooNEexperimentwillnotseeoscillationinneutrinomode,butwillinanti-neutrinomodeSNO,BorexinoestablishLMA,whileKamLANDwillnotseeoscillationKatrinmayseeendpointdistortion

We’llsee!16Maybeevenmoresurprises

inneutrinos!17ImplicationsofNeutrinoMass18MassSpectrumWhatdowedonow?19Twowaystogo(1)DiracNeutrinos:Therearenewparticles,right-handedneutrinos,afterallWhyhaven’tweseenthem?Right-handedneutrinomustbeveryveryweaklycoupledWhy?20ExtraDimensionsRight-handedneutrinosSMgaugesingletCanpropagateinthe“bulk”Makesneutrinomasssmall (Arkani-Hamed,Dimopoulos,Dvali,March-Russell;

Dienes,Dudas,Gherghetta;Grossman,Neubert)mn~1/Rifoneextradim

R~10mmAninfinitetowerofsterileneutrinosNeedalsointer-generationalmixingnow21Twowaystogo(2)MajoranaNeutrinos:TherearenonewlightparticlesWhyifIpassaneutrinoandlookback?Mustberight-handedanti-neutrinosNofundamentaldistinctionbetweenneutrinosandanti-neutrinos!22SeesawMechanismWhyisneutrinomasssosmall?Needright-handedneutrinostogenerateneutrinomassToobtainm3~(Dm2atm)1/2,mD~mt,M3~1015GeV(GUT!),butnRSMneutral23GrandUnificationelectromagnetic,weak,andstrongforceshaveverydifferentstrengthsButtheirstrengthsbecomethesameat1016

GeVifsupersymmetryToobtain m3~(Dm2atm)1/2,mD~mt

M3~1015GeV!Neutrinomassmaybeprobingunification:Einstein’sdreamM3Dimopoulos,Raby,Wilczek24MatterAnti-matterAsymmetry

Whydoweexist?25Big-BangNucleosynthesis

CosmicMicrowaveBackground(Thuan,Izatov)(Burles,Nollett,Turner)2627BaryonAsymmetry

EarlyUniverseTheybasicallyhaveallannihilatedawayexceptatinydifferencebetweenthem10,000,000,00110,000,000,00028BaryonAsymmetry

CurrentUniverseTheybasicallyhaveallannihilatedawayexceptatinydifferencebetweenthem1us29Sakharov’sConditions

forBaryogenesisNecessaryrequirementsforbaryogenesis:BaryonnumberviolationCPviolationNon-equilibrium

G(DB>0)>G(DB<0)PossiblenewconsequencesinProtondecayCPviolation30OriginalGUTBaryogenesisGUTnecessarilybreaksB.AGUT-scaleparticleXdecaysout-of-equilibriumwithdirectCPviolationNowdirectCPviolationobserved:

e’!ButkeepsB–L

0

“anomalywashout”Alsomonopoleproblem31AnomalywashoutActually,SMviolatesB(butnotB–L).InEarlyUniverse(T>200GeV),W/ZaremasslessandfluctuateinW/ZplasmaEnergylevelsforleft-handedquarks/leptonsfluctuatecorrespon-dinglyDL=DQ=DQ=DQ=DB=1

B=L=032TwoMainDirectionsB

L0getswashedoutatT>TEW~174GeVElectroweakBaryogenesis

(Kuzmin,Rubakov,Shaposhnikov)StartwithB=L=0First-orderphasetransitionnon-equilibriumTrytocreateB

L0Leptogenesis

(Fukugita,Yanagida)CreateL

0somehowfromL-violationAnomalypartiallyconvertsLtoB33Leptogenesis34LeptogenesisYougenerateLeptonAsymmetryfirst.GenerateLfromthedirectCPviolationinright-handedneutrinodecayTwogenerationsenoughforCPviolationbecauseofMajorananature(choose1&3)LgetsconvertedtoBviaEWanomaly Morematterthananti-matter

Wehavesurvived“TheGreatAnnihilation”35DoesLeptogenesisWork?Muchmoredetailsworkedout (Buchmüller,Plümacher;Pilaftsis)~1010GeVnR

OKSometensionwithsupersymmetrybecauseofunwantedgravitinooverproductionWaysaround:coherentoscillationofright-handedsneutrino(HM,Yanagida+Hamaguchi)36DoesLeptogenesisWork?Sometensionwithsupersymmetry:unwantedgravitinooverproductiongravitinodecaydissociateslightnucleidestroysthesuccessofBig-BangNucleosynthesisNeedTRH<109GeV(Kawasaki,Kohri,Moroi)37LeptogenesisWorks!Coherentoscillationofright-handedsneutrino

(Bose-Einsteincondensate)(HM,Yanagida+Hamaguchi)InflationendswithalargesneutrinoamplitudeStartsoscillationdo