hot topics in modern cosmology spontaneous workshop xiii 5 ...cosmo/sw_2019/ppt/piacentino.pdf ·...

HottopicsinModernCosmologySpontaneousWorkshopXIII

5-11May2019—IESC,Cargèse

Dedicatedexperimentsongravitationaleffectsonantimatterinspace

GiovanniMariaPiacentino,G.DiSciascio,A.Gioiosa,D.SHajdukovic,A.Palladino,G.Venanzoni.

PresentedbyG.M.Piacentino

MoonVillageScientificEnvironment

•  At the future „Moon village” planned by theEuropeanSpaceAgency,itwouldbepossible,forthe first time in the human history, to performthe same experiment in laboratories withsignificantlydifferentgravitationalbackground.

•  This presentation refers to a proposedexperimentontheinterferenceofgravitationonCPVthatiscompletelymodelindipendent.

•  Nevertheless we will for euristic pourpose firstdescribe one of the possible models of thephenomenon

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OpenproblemsinAstrophysicsandCosmology

•  The Standard Cosmological Model, even ifconcordantonwiththeexperimentonseveralPhenomena*, features an extremely strangestructure,withthe“Magic“ContributeofDarkMatter andDark Energy that reaches 96%ofthetotal.

*i.e. baryon acoustic oscillations (BAO), type-1a supernovae (SN1a)luminosity distance, primordial nucleosynt(hesis and cosmic microwavebackground(CMB))


AcloserglancetotheopenproblemsinAstrophysicsandCosmology

i.  In the observed Universe the matter prevails onantimatterevenifbotharealwayscreatedtogether;

ii.  CMB is not anisotropic nor inhomogeneous enoughto be compatible with the Big Bangmodel withoutthe introduction of a still unknown interactiondrivingtheinflation;

iii.  Giventhegravityweexpecta negativeaccelerationof the expansion. On the contrary that seems toaccelerate;

iv.  Thegravitational fieldofGalaxies,clustersandevenof the Solar system seems much stronger that theoneduetothevisiblematter.

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PresentstateofPossiblesolutionsi.  The mechanism suggested by Sakarov for matter/

antimatter asymmetry is connected to CPV butexperimentallythisphenomenonisfartooweak;

ii.  Models have been proposed to justify inflation bysupersymmetric vacuum energy and SSB but atpresent no evidence for supersymmetry has beenfoundyet;

iii.  DarkEnergyhasbeen introducedbyhand inorder togiveamotivationtotheacceleratedexpansionof theUniverse;

iv.  Dark Matter has been introduced in order to give amotivation to the observed discrepancies betweentheoryandmeasurementsoftheorbitalspeedsofthestarsoftheexternalpartofthegalaxies.


WHYSOMANYDIFFERENTMOTIVATIONS?

Fromthepointofviewoftheelegancethesituationisfarfrombeingsatisfactory:i.  Asmanyhypothesisasproblems;ii.  Mostofthemjustputbyhandintothetheory;iii.  DarkMatterandDarkEnergyhypothesesare

artificial.


Ockham'srazor•  This “lex parsimoniae” Is due to the EnglishFranciscan Scholar Will iam of Ockahm( 1287-1347), who inspired the character ofWilliam of Baskerville in the Umberto Eco’snovel “The name of the Rose1”. It can bepresentedas:

•  If thereare several competing Hypotheses inorder to explain a phenomenon or create atheory, The one that needs the fewestassumptionsandparametersshouldbeselected

•  1)Lecoseeiloronomi,ToraldoDiFranciaLaterza,1986


CanwemasteralltheproblemswithasingleHypothesis?

•  Let’sstartfromMatterAntimattersymmetry:

i.  Matter is always produced with thecorrespondingantimatter;

ii.  Matter seems todominate the landscapeoftheUniverse;

iii. NostableAntimatterseemstopopulateourGalaxynortheUniverseingeneral.


Strong,WeakandelectromagneticInteractionsarelimitedinrange

•  Atthescaleof106meventheelectromagneticinteraction is mostly screened and the onlyresidualinteractionisthegravity;

•  At this scale no significant presence ofantimattercanbefind;

•  Is there any connection between absence ofantimatterandpresenceofgravitation?


Repulsion?•  Antimatter particles correspond tonegativeenergysolution;

•  Could this correspond to a negativegravitational mass and to a consequentgravitational repulsion between matterandantimatter?


Supposethatgravitationalinteractionbetweenmatterandantimatterisrepulsive

•  Thiscouldexplainmatterantimatterasymmetry;

•  ThiscouldbethenatureofDarkEnergy;•  RepulsioncouldhavepoweredtheInflaction;–  Anequalmixofmatterandantimatterwouldgiveanetrepulsiveforce

–  ThiscouldevenbethenatureoftheDarkMatter


Theworkinghypothesis

•  Even if the experiment we are proposing is completelymodel independent, we are fascinated by the workinghypothesisthat,bytheirnature,quantumvacuumfluctuationsarevirtual

gravitationaldipoles•  This hypothesis permits to consider the well established

StandardModelmatter (i.e.mattermade fromquarks andleptonsinteractingthroughtheexchangeofgaugebosons)astheonlymatter–energycontentoftheUniverse;ofcourseacontentimmersedinquantumvacuum.

•  Apparently there is no need to invoke dark matter, darkenergy,inflationfield…

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Fromthegravitationalpointofviewquantumvacuumisacontinuumofvirtualgravitationaldipoles

Therandomorientationofthegravitationaldipolesmakesthetotalgravitationalchargedensityofthevacuumequaltozero


Aroundagalaxyoramassivebody

agravitationalpolarizationisinaction: An halo of the polarized

quantum vacuum acts as aneffective gravitational chargeon the on the boundarybetween the saturated zoneand the non-polarized areawhere a mass density arisesfrom

Sothatgravitationalpolarizationofthequantumvacuummightbethe true nature of what we call Dark Matter and the negativepressureofthepolarizedvacuumfluidcouldbethenatureofDarkEnergy.(thecompletetheoryhasbeenpresentedelsewherebyDraganHajdukovic)


ρqv = −∇⋅

!Pg

Antimattergravitationalexperiments

•  Whitteborn&Fairbanksattempttomeasuregravitationalforceonpositrons

•  LosAlamos-ledteamproposed(1986)tomeasuregravitationalforceonantiprotonsattheCERNLowEnergyAntiprotonRing(LEAR)

•  Projectsendedinconclusively•  toovarioustodescribehere...•  ManyH̅effortsinprogressatCERNAD(ALPHA,ATRAP,ASACUSA,AEgIS,GBAR)


Worldleader:ALPHA*atCERNAntiprotonDecelerator

•  Theymakeantihydrogenfromp-ande+inanoctupolartrapthenshutthemagnetand&seewhetherantihydrogenannihilateonthetoporatthebottom.


Interference,atCERN(AEgIS)andproposedatFermilab(Phillips)


TestingGravitywithMuoniumK.Kirch∗

PaulScherrerInstitut(PSI),CH-5232VilligenPSI,Switzerland


AntigravityandCPVfromP.d.G.

•  “DespitethephenomenologicalsuccessoftheKMCmechanism, it fails (byseveralordersofmagnitude) to accommodate the observedasymmetry [21].This discrepancy stronglysuggests that Nature provides additionalsources of CP violation beyond the KMmechanism.”


CPVandGravity

•  In the1958, eight yearsbefore thediscoveryof CPV, Philip Morrison published on theAmerican Journal of Physics a paper showingthat a strong difference in the gravitationalinteraction for matter and antimatter couldgenerateaCPVinneutralKaonssystem.

•  The CPV in neutral Kaons has been discovered 8yearslater!!


LetusrestricttoCPVintheKs-Klsystem


ConsideranindirectCPV:

KL‘mixes’toKSbeforedecayINDIRECT

• IndirectCP:

The gravitational field is described by theacceleration g so the components ofantimatterandmatterofamesonaredividedbyadistancegrowingwiththetimethatcanbewrittenas:


Δζ = gt 2

Thetimeusefulforthephenomenonisa fraction Ω-½ of the mixing time Δτwhere:


Δτ = π!

Δmc2≈ 5.9x10−10 s ≈ 6τ s

WhereτsisthelifetimeofKs

Thedimensionof a Kmeson is about0.5fmor:


ΔLk =

!mkc

Theratio: ΔζΔLk

Is the adimensionalc o n s t a n t t h a tcharacterizes thephenomenon

Sowehave:


Ωg π 2!2

Δm2c4!mkc

=Ωπ 2! gmk

Δm2c3=Ωx0.88x10−3

AndobtaintheCPVparameteras:


ε =Ωg π 2!2

Δm2c4!mkc

=Ωπ 2! gmk

Δm2c3=Ωx0.88x10−3

ThismeansthatgravitycouldberesponsibleforsomeoftheCPVintheneutralKseenontheEarth

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CPVandGravity

in1992GabrielChardinshowedthatgravityonEarthhastheright intensitytogenerateCPV inthemixingoftheneutralKandBmesons;Healsodemonstratedthat thephenomenonofantigravity for antimatter could be compatiblewith theGeneralRelativityandthat it couldbethe motivation of an instability of quantumvacuum in the presence of strong gravitationalfields,mimicoftheHawkingradiation.


CPVandGravityonTheMoon

i.  Thegravitationalaccelerationonthesurfaceofthe

Moon(1,62m/s2)isaboutsixtimesmallerthanthatoneonthesurfaceoftheEarth. Hence,itwouldbepossible to perform historical experiments in asignificantlydifferentgravitationalfield;

ii.  Inthepastinalltheparticleexperimentgravitationainteractionhasnotbeenconsideredi.eitisageneralsystematicnevermeasurednorextimate;

iii.  We argue that it is feasible to repeat on theMoonthe famous Nobel Prize winning experiment thatrevealedtheCPviolationinaneutralkaonsystem.


ParticlebeamontheMoon


�CRprotonandheliumspectraobtainedfromthebestfitoftheFermiLATMoongamma-raydata. The fit was performed using the MP lunar surface model. The results of the fit(continuous black and red lines) are compared with the proton measurements taken byPAMELA[39]in2008(bluepoints)and2009(purplepoints)andwiththeAMS-02proton[5](cyanpoints)andheliumdata[6](violetpoints).

�PHYSICALREVIEWD93,082001(2016)�(FermiLATCollaboration)

AMS


CPVandGravity

•  On a square target of 70 cm of side, about1.4x 104 protons per secondwill impact, Theenergy of the cosmic protons ranges from afewMeVto∼200GeVwiththemaximumfluxaround 1 GeV and several smaller localmaxima at 5, 13, and 31GeV. This spectrumcan produce the neutral Kaons. The totalnumber of K mesons decays over a spacemission lifetime (> 2 years) will yield therequiredphysicalmeasurement.


AdedicateddetectorontheMoon

•  Wesuggesttheuseofadedicateddetectrotobeinstalled on the Moon surface as part of theMoonVillageprogram;

•  The apparatus should have an active target, amagneticspectrometer,trackerandcalorimeter

•  Active Target: We simulated the production oftheKl“long”(longdecayneutralmesons)andKs(“short”) mesons by the cosmic protons on anappropriatetarget


ActiveTarget

TrackerLayersPermanentMagnet

ECAL28/04/19 g.m.piacentino 34

TheTargetsystem

•  �We performed Geant4 simulations using theangular and energy spectrum of the incidentcosmic protons as measured by AMS-02spectrometer. We simulated incident protonswith θmax = 45◦ over a target surfacecorrespondingtoaπ=4solid-angleacceptance.

•  We considered an active target consisting ofalternating layers of Tungsten and scintillatingcrystals(Stolzite,PbWO4)foratotaldepthof18cm),tobereadwithphotodiodes


•  G.M.Piacentino,A.PalladinoandG.Venanzoni,``Measuring•  gravitationaleffectsonantimatterinspace,''•  Phys.DarkUniv.{\bf13}(2016)162


Kaonsthatdecayinthedetectorvolume


N KLdecays( )year

�Number of KL that decay within various tracking region volumes 50 cmdownstreamofthetarget(50<z<150cm,r<50cmorr<100cm),withandwithoutakinematicalcutontheaxialmomentumattheKS;Ldecayvertex.

Criticalparameters


�Criticalparametersnecessaryfor3σand5σmeasurementsofagravitationalmodulationin the levelofCPviolation (85%change inR) alongwith thevaluesobtained fromourMonteCarlosimulation.TheresultstakeintoaccountabasicgeometricaleventselectionofKS;Ldecayverticeswithina1m×1mcylindricaltrackingvolume50cmdownstreamofthetarget(50<z<150cm,r<50cm),andaxialmomentumattheKS;Ldecayvertexofpz<0:5GeV/c.Thesevaluesassumea100%detectionefficiency,2%(4%)statisticaland2%(4%)systematicfractionaluncertaintiesfor5σ(3σ).

conclusions•  Wehaveproposedapossible testof thegravitationalbehaviorof

antimatterbymeasuring the rateof theCPviolatingdecay in thegravitationalenvironmentoftheMoonsurface.Weestimatethat:

•  5σmeasurementofapossiblechangeintheCPviolationparameterεcouldbeobtainedwithina years,dependingonthedetectionefficiency,fewdayswitha100%efficiency.

•  Anydifferencebetween theamountofCP violationon theMoonwith respect to the level of CP violation on the Earth’s surfacewouldbeanindicationofthenatureofthegravitationalinteractionbetweenmatterandantimatter.

•  A positive resultmay offer an explanation for the cosmic baryonasymmetry andmay offer a contribution to the observed effectsthoughttocomefromdarkmatteranddarkenergy


hot topics in modern cosmology spontaneous workshop xiii 5 ...cosmo/sw_2019/ppt/piacentino.pdf ·...

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