DiracDirac neutrinosneutrinos andand DarkDark MatterMatter
Salvador Centelles Chuliá Instituto de Física Corpuscular (CSIC-Universitat de València)
Works done in collaboration with Ricardo Cepedello, Ernest Ma, Eduardo Peinado, Rahul Srivastava and José WF Valle. OutlineOutline
-Neutrino physics Smallness of neutrino mass Dirac or Majorana? Flavour structure Interactions with matter ...
-Dark Matter Cosmological implications Particle composition of DM Stability of DM components ... CanCan wewe connectconnect thesethese pieces?pieces? Introduction:Introduction: neutrinoneutrino massesmasses
●NeutrinosNeutrinos areare masslessmassless inin thethe StandardStandard ModelModel ●ThereThere isis nono right-handedright-handed neutrino.neutrino.
●However,However, neutrinoneutrino massesmasses areare wellwell establishedestablished byby oscillationoscillation experimentsexperiments
● EnteringEntering thethe precisionprecision eraera (~2%(~2% errorerror inin θθ13)) WhyWhy soso smallsmall masses?masses? AreAre neutrinosneutrinos DiracDirac oror Majorana?Majorana? Introduction:Introduction: seesawseesaw mechanismmechanism ●MostMost popularpopular answeranswer isis thethe seesawseesaw mechanismmechanism.. ●SmallnessSmallness ofof neutrinoneutrino massesmasses isis relatedrelated toto thethe heavinessheaviness ofof messengermessenger fields.fields. ●ManyMany variants:variants: TypesTypes I,I, IIII andand III,III, inverse,inverse, linear…linear… ●TypicallyTypically leadsleads toto MajoranaMajorana neutrinos→neutrinos→ NotNot necessarily!necessarily! ●IfIf neutrinosneutrinos areare Dirac,Dirac, anan extraextra symmetrysymmetry isis neededneeded toto forbidforbid thethe treetree levellevel neutrinoneutrino mass.mass. Majorana seesaw: Dirac seesaw: Minkowski 1977 SCC, Ma, Srivastava, Valle 1606.04543 Gellman-Ramond-Slansky SCC, Srivastava, Valle 1606.06904, Mohapatra-Senjanovc 1980 1706.00210, 1802 05722, 1804.03181 Schechter-Valle 1980 / 1982 Mohapatra-Valle 1986 And many others... Introduction:Introduction: WhyWhy DiracDirac Neutrinos?Neutrinos?
●BlackBlack boxbox theorem:theorem: neutrinolessneutrinoless doubledouble betabeta decaydecay impliesimplies MajoranaMajorana massmass termterm ●NoNo experimentalexperimental signaturesignature (yet)(yet) ●BothBoth possibilitiespossibilities areare openopen DiracDirac && MajoranaMajorana
● ννR maymay bebe neededneeded forfor UVUV completioncompletion justjust asas inin somesome MajoranaMajorana seesawsseesaws ●DiracDirac scenarioscenario isis asas richrich asas thethe MajoranaMajorana oneone
Schechter-Valle 1982 Introduction:Introduction: DiracDirac vsvs MajoranaMajorana
●WeWe denotedenote aa fermionfermion asas ‘Majorana‘Majorana fermion’fermion’ whenwhen itit isis indistinguishableindistinguishable fromfrom itsits ownown antiparticle.antiparticle. ●ConservedConserved chargescharges areare keykey inin determiningdetermining ifif aa fermionfermion isis DiracDirac oror Majorana.Majorana. ●AllAll fermionsfermions inin thethe SMSM (except(except forfor neutrinos)neutrinos) havehave non-non- zerozero electricelectric chargecharge →→ DiracDirac fermions.fermions. ●SymmetriesSymmetries ofof massmass termsterms playplay aa keykey role.role. ●DiracDirac massmass termsterms conserveconserve AbelianAbelian symmetries:symmetries: ΨΨ ΨΨ ●MajoranaMajorana massmass termsterms breakbreak themthem (except(except inin specialspecial c cases):cases): ΨΨ ΨΨ IngredientsIngredients forfor DiracDirac NeutrinosNeutrinos
●MajoranaMajorana massmass termsterms mustmust bebe forbidden.forbidden.
●NotNot onlyonly tree-leveltree-level termsterms butbut alsoalso allall effectiveeffective higherhigher orderorder operatorsoperators leadingleading toto MajoranaMajorana mass.mass.
●ThisThis requiresrequires anan extraextra symmetrysymmetry toto protectprotect ‘Diracness’.‘Diracness’. DarkDark mattermatter problemproblem
●GalacticGalactic rotationrotation profilesprofiles ●LargeLarge scalescale structurestructure ●GalaxyGalaxy clustersclusters gravitationalgravitational massmass ●CMBCMB ……
●NegativeNegative experimentalexperimental resultresult (yet)(yet) ●StabilityStability ofof thethe DMDM candidatecandidate sometimessometimes needsneeds anan extraextra symmetrysymmetry NewNew symmetriessymmetries neededneeded
●DiracDirac neutrinosneutrinos needneed aa symmetrysymmetry toto protectprotect DiracnessDiracness ●DiracDirac seesawseesaw needsneeds aa symmetrysymmetry toto forbidforbid tree-tree- levellevel massmass termterm ●DarkDark mattermatter requiresrequires aa newnew symmetrysymmetry forfor stabilizationstabilization CanCan wewe useuse lessless thanthan 33 symmetries?symmetries? QuarticityQuarticity ZZ44 symmetrysymmetry
●ThisThis symmetrysymmetry isis closelyclosely relatedrelated withwith leptonlepton numbernumber conservation:conservation: discretediscrete versionversion ofof leptonlepton numbernumber oror B-LB-L ●MustMust bebe anan exactexact symmetrysymmetry 4 ●AllAll leptonsleptons transformtransform asas zz (z(z4 == 1).1).
● ΨΨii ~~ z.z. ●AllAll scalarsscalars carryingcarrying aa vevvev transformtransform asas thethe identity:identity: ZZ4 mustmust notnot bebe spontaneouslyspontaneously broken.broken. ●IfIf
SCC, Ma, Srivastava, Valle 1606.04543 DiracDirac neutrinosneutrinos
●AllAll leptonsleptons transformtransform asas zz andand scalarsscalars withwith vevvev asas thethe identity.identity.
● ΨΨii ~~ z,z, IfIf
● ΨΨii ΨΨjj~~ 11 ●ThereforeTherefore c n m 2 ● ΨΨii XX YY ...... ΨΨjj ~~ zz →→ MajoranaMajorana massmass termsterms areare forbiddenforbidden n m ● ΨΨii XX YY ...... ΨΨjj ~~ 1→1→ DiracDirac massmass termsterms areare allowedallowed byby ZZ4.. DarkDark mattermatter stabilitystability
●Reminder:Reminder: AllAll leptonsleptons transformtransform asas zz andand allall scalarsscalars withwith vevvev transformtransform asas thethe identity.identity.
● ΨΨii ~~ z,z, IfIf
●ConnectionConnection betweenbetween thethe DiracnessDiracness ofof neutrinosneutrinos andand DMDM stability.stability. ●DeeplyDeeply relatedrelated withwith leptonlepton numbernumber (or(or B-L).B-L). ●DiracDirac seesawseesaw needsneeds anan extraextra symmetrysymmetry →→ OpenOpen doordoor forfor flavourflavour symmetriessymmetries
SCC, Srivastava, Valle 1606.06904
SCC, Ma, Srivastava, Valle 1606.04543 SCC, Srivastava, Valle 1706.00210 ExampleExample model:model: DiracDirac TypeType II seesawseesaw ●QuarticityQuarticity symmetrysymmetry isis imposedimposed toto ensureensure DiracnessDiracness ofof neutrinos.neutrinos.
●HeavyHeavy neutralneutral DiracDirac fermion,fermion, singletsinglet underunder SU(2)SU(2)L isis introduced:introduced: NNL andand NNR →→ seesaw!seesaw! ExampleExample model:model: DiracDirac TypeType II seesawseesaw
● AA newnew SU(2)SU(2)L singletsinglet scalarscalar withwith non-zeronon-zero vevvev isis neededneeded forfor neutrinoneutrino mass:mass: χχ →→ couplingcoupling betweenbetween NNL χχ ννR ●LeadingLeading orderorder contributioncontribution toto neutrinoneutrino masses:masses: ExampleExample model:model: DiracDirac TypeType II seesawseesaw ●AnAn extraextra symmetrysymmetry isis neededneeded toto forbidforbid thethe treetree levellevel c termterm LL ΦΦ ννR..
● AA simplesimple ZZ2 cancan dodo thethe job→simplejob→simple modelmodel 1606.045431606.04543 ●BiggerBigger symmetrysymmetry groupsgroups cancan leadlead toto flavourflavour predictions:predictions: Δ(27)Δ(27) 1606.069041606.06904,, AA4 1706.002101706.00210..
SCC, Ma, Srivastava, Valle 1606.04543
SCC, Srivastava, Valle 1606.06904
SCC, Srivastava, Valle 1706.00210 Plot extracted from Srivastava, Ternes, Tórtola, Valle 1711.10318 DarkDark sectorsector
●TheThe ‘dark‘dark sector’sector’ ofof thethe modelmodel alsoalso includesincludes aa realreal scalarscalar η~zη~z2 whichwhich connectsconnects thethe darkdark andand thethe visiblevisible sectors:sectors: HiggsHiggs portalportal toto thethe darkdark sectorsector
●TheThe HiggsHiggs bosonboson cancan decaydecay intointo twotwo DMDM particlesparticles (invisible(invisible decay)decay) ●NuclearNuclear recoilrecoil mediatedmediated byby thethe HiggsHiggs bosonboson ExampleExample model:model: DiracDirac TypeType II seesawseesaw
●QuarticityQuarticity symmetrysymmetry ensuresensures bothboth DiracnessDiracness andand DMDM stabilitystability (higgs(higgs portal,portal, WIMPWIMP DM).DM).
●NeedsNeeds anan extraextra symmetrysymmetry toto forbidforbid treetree levellevel massmass termterm andand thereforetherefore havinghaving naturalnatural smallsmall massesmasses implementingimplementing aa DiracDirac seesaw.seesaw. ThisThis extraextra symmetrysymmetry cancan bebe aa flavourflavour symmetry.symmetry. ChiralChiral anomalyanomaly freefree B-LB-L
●B-LB-L alreadyalready inin SMSM asas anan ‘accidental‘accidental symmetry’symmetry’
● ExoticExotic chargescharges underunder B-LB-L forfor ννR forbidforbid thethe treetree levellevel massmass term.term.
●NeutrinoNeutrino massesmasses comecome fromfrom aa looploop withwith extraextra vevvev insertionsinsertions andand extraextra intermediateintermediate chiralchiral fermions.fermions.
●TheThe chargescharges ofof thethe newnew particlesparticles mustmust cancelcancel thethe triangulartriangular anomalies.anomalies.
Cepedello, SCC, Peinado, Srivastava 1809.XXXXX Coming soon. Stay tuned! ChiralChiral anomalyanomaly freefree B-LB-L
●The charges of the scalars with vev will determine the breaking pattern of B-L
● If U(1)U(1)B-L breaksbreaks spontaneouslyspontaneously toto anan eveneven ZZn thenthen wewe cancan havehave anan stablestable scalarscalar DMDM candidate.candidate. ●IfIf thethe lightestlightest particleparticle inin thethe looploop isis anan scalarscalar andand hashas anan
oddodd chargecharge underunder ZZn itit willwill bebe stablestable duedue toto LorentzLorentz
invarianceinvariance andand ZZn.. ●IfIf neutrinosneutrinos dodo notnot transformtransform asas nn oror 00 underunder thethe remnantremnant
ZZ2n (note(note thisthis isis notnot possiblepossible withwith ZZ2 →minimum→minimum groupgroup isis ZZ4))
theythey areare automaticallyautomatically DiracDirac particles.particles.
Cepedello, SCC, Peinado, Srivastava 1809.XXXXX Coming soon. Stay tuned! ChiralChiral anomalyanomaly freefree B-LB-L
● OneOne symmetrysymmetry toto rulerule themthem all:all: ●NeutrinosNeutrinos areare DiracDirac fieldsfields ●StabilityStability ofof DarkDark mattermatter ●SmallSmall neutrinoneutrino massesmasses viavia loopsloops
B-LB-L
Cepedello, SCC, Peinado, Srivastava 1809.XXXXX Coming soon. Stay tuned! ExampleExample model:model: B-L→B-L→ ZZ66
●TheThe chargescharges ofof thethe particlesparticles inin thethe exampleexample modelmodel areare givengiven byby
●OneOne cancan checkcheck thatthat triangulartriangular anomaliesanomalies areare cancelledcancelled (including(including gravity)gravity) ExampleExample model:model: B-L→B-L→ ZZ66
●2-loop2-loop neutrinoneutrino massesmasses andand symmetrysymmetry breakingbreaking pattern:pattern:
● TheThe lightestlightest scalarscalar inin thethe looploop -for-for exampleexample ηη1-- willwill bebe stable.stable. EasyEasy toto checkcheck inin thethe rightright diagramdiagram afterafter SSB.SSB. Take-homeTake-home ideasideas
● NeutrinosNeutrinos cancan bebe DiracDirac –– openopen possibilitypossibility ● AA newnew symmetrysymmetry toto protectprotect DiracnessDiracness isis neededneeded →→ LeptonLepton numbernumber (or(or B-L)B-L) isis aa naturalnatural option.option. ● SeesawSeesaw mechanismmechanism isis compatiblecompatible withwith DiracDirac neutrinoneutrino massesmasses.. ● ThereThere cancan bebe aa deepdeep connectionconnection betweenbetween DiracnessDiracness andand darkdark mattermatter stabilitystability→→ Example:Example: QuarticityQuarticity symmetrysymmetry ● Chiral,Chiral, anomaly-freeanomaly-free B-LB-L cancan leadlead toto smallnesssmallness ofof neutrinoneutrino mass,mass, DiracDirac neutrinosneutrinos andand stablestable DMDM withoutwithout thethe needneed ofof extra extra symmetriessymmetries.. ThankThank youyou forfor youryour attentionattention ●Questions?Questions?
●References:
●Dirac Neutrinos and Dark Matter Stability from Lepton Quarticity. SCC, Ernest Ma, Rahul Srivastava, José W.F. Valle. Phys.Lett. B767 (2017) 209-213. ●CP violation from flavor symmetry in a lepton quarticity dark matter model. SCC, Rahul Srivastava, José W.F. Valle. Phys.Lett. B761 (2016) 431-436.
●Generalized Bottom-Tau unification, neutrino oscillations and dark matter: predictions from a lepton quarticity flavor approach. SCC, Rahul Srivastava, José W.F. Valle. Phys.Lett. B773 (2017) 26-33. ●Scotogenic dark matter and Dirac neutrinos using only Standard Model symmetries Ricardo Cepedello, SCC, Eduardo Peinado, Rahul Srivastava 1809.XXXXX Stay tuned!