Lepton dipole moments and light (scalar) dark matter as windows to go beyond the Standard Model Antonio Masiero INFN and Univ. of Padova Kavli IPMU, Tokyo, Nov. 14, 2019
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Leptondipolemomentsandlight(scalar)darkmatter
aswindowstogobeyondtheStandardModel
AntonioMasieroINFNandUniv.ofPadova
Kavli IPMU,Tokyo,Nov.14,2019
-- hintsofviolationoftheleptonflavoruniversalityinsemileptonicBdecays(??)
• ValueoftheHubbleconstantmeasuredtodayorinferredfromthePlanckresultsontheCMB
5numbers,5indicationsofphysicsbeyondtheStandardModelsofParticlePhysicsandCosmology:NEUTRINOMASSES,DARKMATTER,DARKENERGY,ANTIMATTER andVACUUMENERGY
>0.1%
~68%
~27%
0%
1062 % ??thankstoH.Murayama
Thequestioncanberephrasedinto:IsDMagoodhonestweakly(butnottooweakly)interacting (withtheSMparticles)massive(typicallyO(100GeV))particle,i.e.a“traditional”WIMPpartofanextensionoftheSMaccountingfora(possiblynatural)explanationofthe(incrediblysmall)electroweaksymmetrybreakingscaleMW (ascomparedtothePlanckscaleMPl) andconstitutinganSMUVcut-offattheTeV scale?
OrIsDMunrelatedtotheexistenceofanaturalsolutionofthegaugehierarchyproblem.i)Inthiscase DMcanbepartofanSMextensionatE>>MW (forinstanceE~mutiTeV)andthen,presumably,MDM >O(1TeV)(heavyDM)orii)DMcouldbea(very)lightparticlecouplingveryweaklytotheSMparticlesbeingpartofanewdarksectorofthetheorycommunicatingwiththeSMparticlesonlythroughaspecific“portal”,i.e.oneormoreparticlesbridgingthe“darkworld”with”our”SMworld(inthiscasetheDMsectorisnotpartofalargertheoryextendingtheSM,butitcouldbeaseparatesectorofthetheory)
TheDMdilemma:tobeor nottoberelatedtotheelectroweaksymmetrybreaking?
ProsandconstobeaWIMPDM(I)Pros:• i)theWIMPcoincidenceoremphaticallydubbed“WIMPmiracle”(namely:takeaweaklyinteractingO(100GeV)particleonceinthermalequilibriumandcomputeitsnumberdensitytoday– result:typicallyoneendsupwithnWIMP ~10-8 cm-3 leadingtothecorrectDMamount!;
• ii)suchWIMPDMtypicallyconstitutesaformofCOLDDM(hencecorrectlyaccountingforthemainbulkofobservationsonlargescalestructuresdistribution)
• iii)remarkablyenough,themainSMextensionsenvisagedtocopewith”natural”explanation ofthegaugehierarchypuzzleMW <<MPlentailthepresenceofastableparticle,typicallythelightestofthenewparticles characterizingsuchSMextension,whichisapotentiallygoodWIMPDMcandidate.
ProsandconstobeaWIMPDM(II)Thecons:i) Inspiteofconstitutingthemost“wanted”particlecandidateforDM,no
WIMPsignal(oratleasthint)haseveremergedwithsearchesreachingsensitivitiestoWIMP-nucleicrosssectionsdownto10-10 pb;
ii) Thenegativeresultscomingfromhigh-energyandflavourphysics(inparticularLHC)searchesofnewphysicsparticlesaroundthecorner,i.e.intheO(1TeV)massrange,have(largely)reducedourenthusiasmforaTeV newphysicsdirectlylinkedtoanaturalsolutionoftheMW <<MPlgaugehierarchyproblem.And,asaconsequence,thelightestTeV newphysicsparticlehaslostitsappealas“natural”candidateforDM
iii) Themain“victim”ofthislostconnectionDM– TeV newphysicsisundoubtedlytheLightestSUSYParticle,LSP,typicallythelightestneutralino inSUSYmodelswithRparity
SummarytalkbyAsai andCatenaoftheDMWGattheEUStrategyGranadaSymposium
SummarytalkbyAsai andCatenaoftheDMWGattheEUStrategyGranadaSymposium
MaximPospelov,PhysicsBeyondCollidersatCern:BeyondtheStandardModelWorkingGroupReport
MaximPospelov
New physics Λ energy scale and (g-2)μIf New Physics (NP) at a scale Λ gives the contribution δmμto the muon mass, then such NP leads to a loop contribution to the muon magnetic moment aμ :
Czarnecky and Marciano, 2001; Stockinger 2010
~ O(α/4π) if perturbative contributions to the muon mass
~ O (1) if the muon mass is radiatively induced
If the g-2 discrepancy between exp. and SM expectation is a real fact and if we invoke NP to account for it, then
Λ NP has to be at or below the TeV scale !
Minimal extensionsoftheSMtoaccountforthe(g-2)μ anomaly
AdditionofaSINGLENEWFIELD:i) Theadditionofasinglefermioncannotexplainthisanomaly;(C.Biggio 2008;Freitas,Lykken,Kell,Westhoff 2014;Biggio,Bordone 2014)
ii) Theadditionofasinglescalarcanaccountforthediscrepancyifthenewscalaris:anewHiggsdoublet;(Freitas,Lykken,Kell,Westhoff 2014;Broggio,Chun,Passera,Patel,Vempati 2014;Biggio,Bordone 2014;Cherchiglia,Kneschke,Stockinger,Stockinger-Kim2017)
oneofthetwoleptoquarks:S1/3(3,1,-1/3;Q=-1/3);D7/6(3,2,7/6;Q=5/3,2/3) Chakraverty,D.Choudhuri,Datta 2001;Biggio,Bordone 2014;Queiroz,Shepherd2014;Coluccio Leskow,D’Ambrosio,Crivellin,Muller2017
• iii) onemassivevectorboson:onlypossibilityà abeliangaugeextensions– Z’,darkphoton(Biggio,Bordone,DiLuzio,Ridolfi2016;Davoudiasl,H.-S.Lee,Marciano2014;Altmannshofer,C.-Y.Chen,Dev,Soni 2016;)
• iv)ALPs(ALP-photonphoton+ALPYukawainteractionswithleptons)
One-loopcontribution
Two-loopcontributions
Chen,Davoudiasl,Marciano,Zhang2016
Marciano,Masiero,Paradisi,Passera 2016
Pseudoscalar 1σsolutionbandstotheg-2muonanomalytakingΛ =1TeV
Scalar1σsolutionbandstotheg-2muonanomalytakingΛ =1TeV
Marciano,Masiero,Paradisi,Passera 2016
yaμ
Marciano,Masiero,Paradisi,Passera
DMandg-2aswindowstoNewPhysics
• MinimalextensionsoftheSMtoaccountfortheDM:oneadditionalfieldthatbeingneutralandstablemighthavebeeninthermalequilibriuminteractingwithordinarymatterandtodayhavethecorrectdensitytoaccountfortheDM
• MinimalextensionsoftheSMtoaccountfortheg-2anomaly:onesingleadditionalfield(leptoquark oradditionalHiggsdoubletorALPs)couplingsizeablytoleptonsand/orphotons
• IsitpossibletohavejustonesingleadditionalfieldtoaccountforboththeDMand theg-2anomaly?No,theDMfieldsintheseminimalSMextensionsdecaytooquicklytoordinarymatterparticles.Oneneedsatleasttwonewfields (forinstanceoneadditionalfermionandoneadditionalscalar) Calibbi,Ziegler,Zupan 2018
Calibbi,Ziegler,Zupan 2018
F-Sone-loopcontributiontog-2DMannihilationsintoordinarymatter
ModelswithoutandwithHiggsinsertion
Dark(light)greenregionà totalcontributiontog-2compatibleat1(2)σwiththeexperimentalresult
Calibbi,Ziegler,Zupan 2018
ModelswithoutHiggsinsertion
ModelswithHiggsinsertion
Calibbi,Ziegler,Zupan 2018
Twoleptonic g-2anomalies?Recent(Parkeretal.2018)moreprecisedeterminationofthefinestructureconstant
2.4σ discrepancy(oppositeinsignw.r.t.tothemuoncase)
Asinglescalarsolutiontobothanomalies?Yes,ifthetwo-loopBarr-Zeediagrams
dominateovertheoneloopscalarcontributionstothe(g-2)e
withrelativelylargecouplingstotheelectronandthetwophotonsDavoudiasl andMarciano2018
Combinedexplanationof(g-2)e AND(g-2)μwithalargemuonEDM
• EFTanalysis(Crivellin andHoferichter,May2019)
SimultaneousexplanationpossibleinmodelswithchiralenhancementBut,
veryimportant,oneneedsaDECOUPLINGoftheelectronandmuon
BSMsectorstoavoidtheverystringentlimitonBR(μà e+Ɣ)
SuchdecouplingentailsthatthereisnocorrelationbetweentheEDMsoftheelectronandmuon,i.e.theverystringentboundonde doesnotnecessarilyimplyaverysmalldμ
?
Post– LHCphysics
Lepton(g-2),EDMsandDMaspossibleLIGHTHOUSE
Backupslides
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