Hot topics in Modern Cosmology Spontaneous Workshop XIII 5 - 11 May 2019 — IESC, Cargèse Dedicated experiments on gravitational effects on antimatter in space Giovanni Maria Piacentino, G. Di Sciascio, A. Gioiosa, D.S Hajdukovic, A. Palladino, G. Venanzoni. Presented by G.M. Piacentino
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Hot topics in Modern Cosmology Spontaneous Workshop XIII 5 ...cosmo/SW_2019/PPT/Piacentino.pdf · effects on antimatter in space Giovanni Maria Piacentino, G. Di Sciascio, A. Gioiosa,
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• 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. 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.
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
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CanwemasteralltheproblemswithasingleHypothesis?
• Let’sstartfromMatterAntimattersymmetry:
i. Matter is always produced with thecorrespondingantimatter;
ii. Matter seems todominate the landscapeoftheUniverse;
iii. NostableAntimatterseemstopopulateourGalaxynortheUniverseingeneral.
• 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
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)
• “DespitethephenomenologicalsuccessoftheKMCmechanism, it fails (byseveralordersofmagnitude) to accommodate the observedasymmetry [21].This discrepancy stronglysuggests that Nature provides additionalsources of CP violation beyond the KMmechanism.”
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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!!
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LetusrestricttoCPVintheKs-Klsystem
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ConsideranindirectCPV:
KL‘mixes’toKSbeforedecayINDIRECT
• IndirectCP:
The gravitational field is described by theacceleration g so the components ofantimatterandmatterofamesonaredividedbyadistancegrowingwiththetimethatcanbewrittenas:
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Δζ = gt 2
Thetimeusefulforthephenomenonisa fraction Ω-½ of the mixing time Δτwhere:
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Δτ = π!
Δmc2≈ 5.9x10−10 s ≈ 6τ s
WhereτsisthelifetimeofKs
Thedimensionof a Kmeson is about0.5fmor:
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ΔLk =
!mkc
Theratio: ΔζΔLk
Is the adimensionalc o n s t a n t t h a tcharacterizes thephenomenon
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.
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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.
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ParticlebeamontheMoon
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�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).
• 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.
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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
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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
�Number of KL that decay within various tracking region volumes 50 cmdownstreamofthetarget(50<z<150cm,r<50cmorr<100cm),withandwithoutakinematicalcutontheaxialmomentumattheKS;Ldecayvertex.
Criticalparameters
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�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).
• 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