La lecture à portée de main
Description
Sujets
Informations
Publié par | technischen_universitat_dortmund |
Publié le | 01 janvier 2008 |
Nombre de lectures | 8 |
Langue | English |
Poids de l'ouvrage | 1 Mo |
Extrait
FlavorPhysics:
NeutrinoproductionofResonances
andSemileptonicB!K,Kl¯l
Decays
Dissertation
zurErlangungdesGradeseines
DoktorsderNaturwissenschaften
desFachbereichesPhysik
derTechnischenUniversit¨atDortmund
vorgelegtvon
GiorgiPiranishvili
August2008
Abstract
Thegoalofthisresearchisthepreciseinvestigationsoftheprocesseswhichare
helpfultotestthephysicsoftheStandardModelandbeyondit.Weconcentrate
ontheavorsectorofthetheorywhichisstilloneofthestickingpointinhigh
energyphysics.Atthesametimeavorphysicspossessesarichphenomenology
whichmakesitoneofthehottopicsinthecurrenttheoreticalandexperimental
investigations.
Inthisthesiswepresentthestudiesofseveralprocessesofparticlephysicstaking
placeattheenergyscaleofO(GeV),namelyneutrinointeractionswithnucleons
andsemileptonicBmesondecays.
FortheneutrinoscatteringonnucleonswithneutrinoenergiesofaboutoneGeV,
wedeterminetheformfactorsofthenucleon-resonancetransitionwiththehelpof
therecentelectroproductiondata.Weextendtheanalysistothesecondresonance
region,whereinadditiontotheresonanceP33(1232),alsoD13(1520),P11(1440)and
S11(1535)resonancescontribute.Usingtheupdatedformfactortwecalculatethe
dierentialandtotalcrosssectionsfortheresonanceproductionbyneutrinos.
AdetailedanalysisofangulardistributionsisdonefortheexclusivedecaysB!
K,Kl¯l.ThecalculationsareperformedinthelargerecoilregionusingtheQCD
factorizationformalism.WegivetheStandardModelpredictionsforthecoecients
ofangulardistributionofB!Kl¯ldecays,namelyFHlandAlFB.Thepredicted
valuesareremarkablefortheirvanishingvaluesintheStandardModelandsmall
theoreticaluncertainties.ThesensitivityofthesecoecientstoNewPhysicsis
studiedinamodel-independentway.
InthecaseofthedecayB!K(!K)l¯lweinvestigateeightCPasymmetries
intheStandardModelandBeyond.ThreeofthemareT-oddandveT-evenCP
asymmetries.IntheStandardModel,wheretheCPviolationcomesfromtheCKM
matrix,wepredictthevaluesoftheCPasymmetriestobeofO(103).Wealsoshow
thatthecurrentexperimentalboundsallowtheT-oddasymmetriestobeofO(1),
whereasthevaluesoftheT-evenasymmetriescanbeofO(0.1)inthepresenceof
NewPhysics.
Zusammenfassung
IndieserArbeitpra¨sentierenwirdieStudieneinigerausgewa¨hlterProzesseder
Teilchenphysik,dieanderEnergieskalavonO(GeV)stattnden,erstensdieWech-
selwirkungzwischenNeutrinosundNukleonenundzweitenssemileptonischeZerfa¨lle
derB-Mesonen.
ImFallederStreuungvonNeutrinosanNukleonenimEnergiebereichvonca.1
GeV,bestimmenwirdieFormfaktorenderNukleon-Resonanz-U¨berga¨ngemitHilfe
neuesterElektron-NukleonStreuungs-Daten.UnsereAnalysebeinhaltetaußerder
P33(1232)ResonanzauchdieD13(1520),P11(1440),S11(1535)Resonanzen.Unter
VerwendungdieseraktualisiertenFormfaktorenberechnenwirdendierentiellen
undgesamtenWirkungsquerschnittfu¨rdieErzeugungvonResonanzeninderNeu-
trino-NukleonStreuung.
ImFalledersemileptonischenB-Mesonzerfa¨llewerdenWinkelverteilungendesSpek-
trumsfu¨rdieexklusivenZerfa¨lleB!K,Kl¯ldetailliertdiskutiert.DieRechnung
beschra¨nktsichaufkleineinvarianteMassendesDileptonsystemesimRahmendes
FormalismusderQCDFaktorisierung.WirbestimmendieStandardmodellVorher-
sagederKoezientenderWinkelverteilungFHlundAlFBdesZerfallesB!Kl¯l.
DieseObservablenzeichnensichdurchihreverschwindendkleinenStandardmodell-
werteundkleinenUnsicherheitenaus.DesweiterenwirddieSensitivita¨tdieserKo-
ezientenaufSignaleNeuerPhysikinmodellunabha¨ngigerArtundWeisestudiert.
Fu¨rdieZerfa¨lleB!K(!K)l¯luntersuchenwirachtCPAsymmetrienimStan-
dardmodellunddaru¨berhinaus.DreivonihnensindT-ungeradeundfu¨nfT-gerade
CPAsymmetrien.ImStandardmodellistdieUrsachederCPVerletzungdieCKM
MatrixunddieCPAsymmetrienverschwindendkleinimBereichO(103).Wir
zeigenaußerdem,dassdiegegenwa¨rtigenexperimentellenDatenkeinewesentlichen
Einschra¨nkungendarstellenundfolglichdieT-ungeradenAsymmetrienimFalle
NeuerPhysikimBereichO(1)seinko¨nnen.DieSensitivita¨tderT-geradenAsym-
metrienaufSignaleNeuerPhysikistetwaskleiner,dieseko¨nnenimBereichO(0.1)
liegen.
Contents
1Basics1
1.1FlavorintheStandardModel......................1
1.2FromQuarkstoHadrons.........................4
1.2.1QCDLagrangian.........................4
1.2.2QuarkModelofHadrons.....................7
1.2.3FlavorSymmetries:IsospinandSU(3).............8
1.2.4HeavyQuarkSymmetry.....................12
1.3EectiveTheoryofElectroweakProcesses...............13
1.3.1Idea................................13
1.3.2HadronicMatrixElements....................15
2ResonanceProductionbyNeutrinos17
2.1Introduction................................17
2.2FormalismofResonanceProductioninNeutrino-NucleonInteractions19
2.2.1CrossSection...........................19
2.2.2HadronicMatrixElement....................20
2.3DeterminationofHelicityAmplitudesinElectroproduction......22
2.4CalculationoftheAmplitudes......................23
D13D13D13
2.4.1A,AandS.......................24
3/21/21/2
2.4.2HelicityAmplitudesfortheP(1232)Resonance.......26
332.4.3HelicityAmplitudesfortheP(1440)Resonance.......26
112.4.4HelicityAmplitudesfortheS(1535)Resonance........27
112.5DataAnalysisandtheExtractionsoftheFormFactors........28
2.5.1D(1520).............................29
312.5.2P(1232).............................30
332.5.3P(1440).............................30
112.5.4S(1535).............................31
112.6DecaysoftheResonancesandPCAC..................32
2.6.1P(1232).............................34
332.6.2D(1520).............................35
312.6.3P(1440).............................36
11
i
2.6.4S(1535).............................36
112.7CrossSectionsintheSecondResonanceRegion............37
2.8Conclusions................................39
¯3AngularAnalysisofB!K,KllDecays41
3.1Introduction................................41
¯3.2EectiveHamiltonianforb!sll....................42
3.3SomeNewPhysicsModels........................46
3.3.1MSSMwithLargetan.....................46
3.3.2ModelswithBrokenR-parity..................48
3.3.3Leptoquarks............................50
3.4FormFactorsandLargeRecoilLimit..................53
3.5StandardModelAnalysis........................57
¯3.5.1AngularDistributioninB!Kll................58
¯3.5.2AngularDistributioninB!K(!K)ll...........65
3.6NewPhysicsAnalysis...........................78
3.6.1ExperimentalConstraints....................79
¯3.6.2B!Kll:BeyondtheStandardModel.............87
3.6.3CPAsymmetriesinthePresenceofNewPhysics.......97
3.7Conclusion.................................102
4Summary
501
AResonanceProductionbyNeutrinos107
A.1StructureofHadronicTensorforP33andD13.............107
A.2StructureoftheHadronicTensorforP11andS11...........109
BAngularAnalysisofB!K,Kl¯lDecays111
B.1AngularCoecientsJi(a).........................111
B.2OptimalObservablesfromOptimalWeights..............112
B.3CPAsymmetriesandAFBbeyondtheSM...............112
B.4TaAmplitudes...............................114
B.5Model-independentCPAsymmetriesbeyondtheSM.........119
Bibliography
ii
311
Introduction
Thedevelopmentsofthelast50yearsinparticlephysicsgivethehopethatthe
descriptionofthenaturecanbearrangedintermsofseveralfundamentalprinciples.
TheStandardModel(SM)[1,2,3],themodeldescribingelectromagnetic,weakand
stronginteractions,issuchanattempt.Withthehelpofthequantumeldtheory
andtheprincipleoflocalgaugeinvariancetheSMexplainssuccessfullythewide
rangeofparticlephysicsphenomenauptodistancesofO(1018m),whichhasbeen
conrmedbyalargenumberofacceleratorexperiments.
InspiteofitssuccessonebelievesthattheSMisnotcomplete.Thereasonisa
numberofunansweredquestionsraisedinthetheory.Namely,thereisanumberof
parametersinthetheorywhosevaluesareunnaturallyremotefromeachother,more
thanonewouldexpect.Forexample,thereisalargedierence,aboutseventeen
ordersofmagnitude,betweentheelectroweakscaleandthePlanckscale.Similarly,
itisunclearwhythespectrumofmatterparticlesintheSMissodierent.The
massofthetopquarkexceedsthemassofoneoftheneutrinosbyelevenorders
ofmagnitude.Thisproblemisprobablycorrelatedwiththequestion:”Wheredo
massesoftheparticlescomefrom?”.Wealsodonotknowwhythereareonlythree
generationsofparticles.Although,thedirectexperimentalconstraintsstilldonot
ruleoutanadditionalfourthgeneration[4,5].TheneutrinosaremasslessintheSM,
whereastheoscillationexperimentsconrmedthatneutrinoshavemasses.Another
problemisrelatedtothefactthatourUniverseisobservedtohaveanexcessof
matteroverantimatter.Itwouldbeimpossibletoachieveitwithouttheexistence
ofCPviolatingprocessesduringtheevolutionoftheUniverse[6].Thus,itgenerates
theneedtohaveCPviolationinthetheory.Unfortunately,theamountofCP
violationintheSMisnotenoughtoexplainquantitativelytheasymmetrybetween
matterandantimatter.Thus,theseshortcomingsandinconsistenciesmotivateus
tothinkabouttheexistenceofphysicsbeyondtheSM,i.e.,NewPhysics(NP).We
hopethatthededicatedexperimentsattheLargeHadronCollider(LHC)willshed
lightonsomeofthesequestions.
Themostpartofthismanuscriptisdevotedtovariousphenomenologicalaspects
ofavorphysics.IntheSMthematterparticles(fermions)appearinthreegen-
erations.Flavorphysicsdescribestheinteractionsresponsibleforthetransitions
betweendierentgenerations.Therearetwosec