old experiments in a new environment. quantum gravity ...€¦ · quantum gravity effects from an...

Oldexperimentsinanewenvironment.QuantumGravity

effectsfromanexperimentalpointofview

G.M.PiacentinoUniversita’delMolise,INFNRoma2,

INAFMilano

OpenproblemsinAstrophysicsandCosmology

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 the oneduetothevisiblematter.

g.m.piacentino12/04/18 2

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 betweentheoryandmeasurementsof theorbital speedof thestarsoftheexternalpartofthegalaxies.


WHYSOMANYDIFFERENTMOTIVATIONS?

From the point of view of the elegance thesituationisfarfrombeingsatisfactory:i.  Asmanyhypothesisasproblems;ii.  Mostofthemjustputbyhandintothetheory;iii.  DarkMatter and Dark Energy hypotheses are

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 to negative energy

solution;•  Could this correspond to a negative gravitationalmass

and to a consequent gravitational repulsion betweenmatterandantimatter?


Supposethatgravitationalinteractionbetweenmatterandantimatterisrepulsive

•  Thiscouldexplainmatterantimatterasymmetry;

•  ThiscouldbethenatureofDarkEnergy;•  ThiscouldbethenatureofDarkMatter;•  RepulsioncouldhavepoweredtheInflaction;

–  Anequalmixofmatterandantimatterwouldgiveanetrepulsiveforce.


IsthiscompatiblewithGR?

Whatisantimatter?

(Feynman~Stueckelberg)Definition:Matter(TimereversalxChargesconiugation)Antimatter

WhatkindoftimereversalistheonetobeusedinGR?

HowantimatteraffectsGravitation?

11.m.piacentino12/04/18

TaxonomyofmatterinGR:

InGR.Mattercanevolve,symmetrically,inthepositiveornegativetimedirection

12/04/18 12.m.piacentino

SowecanclassificaterespecttoasystemofreferencethatisnotInmotionrespecttothematter.IfwedefinepositivetheprotonwithPositivecharge,wehaveinprinciplefourdifferenttypeofmatter:

q+ τ-

q+

τ+

q-

τ+

q-

τ-

Whereτisthepropertime

TaxonomyofmatterinGR:

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τisthepropertimesowehave:

dτ = dxµdxµ = dtγ

Bothsignsareallowedtoτsince γ = 11− β 2

Achangeinthesignofϒ affects also:

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m = m0γ ;uµ = γ (1,u)pµ = m0γ (1,u)Sothemassisoddunderpropertimeinversion

Thisistruealsofortheenergystresstensorinfact:


E = pµuµ;pµ = T µνuν ;E = T µνuµuν ;

Sowe can introduce the time reversal inordertounderstandhowantimatterbehavesfromthepointofviewofamattermadeobserver:


τ → −τ

q→−q

t→−t

τ → −τ q→−q t→−t

mqτxµ

uµ

pµ

duµ

dτ

T µν

−+−

−−

−

−

−−−−

−−−−

−

−

+ ++

+ ++ +

+ ++ +

+ +

+ +

17

antimatter and antigravity are connected classical concepts

•  Several opposition based on three points:

•  1) energy conservation violation

•  2) equivalence principle violation

•  3) Induction of CPV

•  Most of them not valid (Nieto et al.)

12/04/18 .m.piacentino

Theworkinghypothesis

•  Even if the experiments proposed are completely modelindependent,we are fascinated by theworking hypothesisthat,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…

18

Fromthegravitationalpointofviewquantumvacuumisacontinuumofvirtualgravitationaldipoles

Therandomorientationofthegravitationaldipolesmakesthetotalgravitationalchargedensityofthevacuumequaltozero

19

Aroundagalaxyoramassivebodyagravitationalpolarizationinin

action: An halo of the

polarized quantumvacuum acts as aneffectivegravitationalchargeontheontheboundary betweenthe saturated zoneandthenon-polarizedarea

So that gravitational polarization of thequantumvacuummightbe the truenatureofwhatwecalldarkmatter.

20

Darkmattercouldbealocaleffectofthe

gravitationalpolarizationofthequantumvacuum•  Agravitationalpolarizationdensity(i.e.thegravitationaldipole

momentperunitvolume)maybeattributedtothequantumvacuum.

•  Thespatialvariationof,generatesagravitationalboundchargedensityofthequantumvacuum

Inthecaseofsphericalsymmetry

Thiscalculationsseemsinagreementwithresultsforgalaxies

21

!Pg

!Pg

ρqv = −∇⋅

!Pg

ρqv(r)=1r2ddr

r2Pg r( )⎛⎝⎜

⎞⎠⎟ ;

Pg r( )≡ !Pg r( )

Effectivegravitationalchargeofabodydependsondistancefromit

22

AntigravityandCPVfromP.d.G.

•  “DespitethephenomenologicalsuccessoftheKMmechanism, it fails (by several orders ofmagnitude) 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!!


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

12/04/18 31g.m.piacentino

CPVandGravity

In 1992 Gabriel Chardin showed that gravity onEarthhastherightintensitytogenerateCPVinthemixingoftheneutralKandBmesons;•  He also demonstrated that the phenomenon ofantigravity for antimatter could be compatiblewith the General Relativity and that it could bethe motivation of an instability of quantumvacuum in the presence of strong gravitationalfields,mimicoftheHawkingradiation.


Soifthegravitationalinteractionbetweenmatterandantimatterisrepulsive

•  Thiscouldexplainmatterantimatterasymmetry;

•  ThiscouldbethenatureofDarkEnergy;•  RepulsioncouldhavepoweredtheInflaction;

–  Anequalmixofmatterandantimatterwouldgiveanetrepulsiveforce

–  ThiscouldevenbethenatureoftheDarkMatter


Howtomakeexperiments?

Antimattergravitationalexperiments

•  Whitteborn&Fairbanksattempttomeasuregravitationalforceonpositrons

•  LosAlamos-ledteamproposed(1986)tomeasuregravitationalforceonantiprotonsattheCERNLowEnergyAntiprotonRing(LEAR)

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


Worldleader:ALPHA*at

CERNAntiprotonDecelerator•  Theymakeantihydrogenfromp-ande+ inanoctupolar trapthenshutthemagnetand &see whether antihydrogen annihilate on thetoporatthebottom.


Interference,atCERN(AEgIS)andproposedatFermilab(Phillips)


TestingGravitywithMuoniumK.Kirch∗

PaulScherrerInstitut(PSI),CH-5232VilligenPSI,Switzerland


CPVandGravity

i.  On a circular LEO at 500 Kilometers, gravity isabout 10% less than on Earth.On aGEOorbitthe intensityof theof theEarth’s gravitationalfieldisoftheorderoffewpercent.ThisislikelytocausealargefluctuationofanygravitationalcontributiontotheCPVinthe2-statesystemoftheneutralKmesons.•Furthermore inorbit,alargefluxofenergeticprotonsispresentandisonlymildlymodulatedby theEarth’smagneticfield.


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.


AdedicatedSatellite

•  WEsuggestedtheuseofadedicatedSatellite•  Our payload proposed to ESA is aimed atperforming a particle physics experiment ino rb i t w i th ac t i ve ta rget , magnet i cspectrometer,trackerandcalorimeter

•  ActiveTarget:WesimulatedtheproductionoftheKl“long”(longdecayneutralmesons)andKs(“short”)mesonsbythecosmicprotonsonanappropriatetarget


ActiveTarget

TrackerLayersPermanentMagnet

ECAL

Klongproduction

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


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


Withmomentumcut

Thenextopportunity

•  TheenvironmentontheMoonhasnumerouspeculiarities that make it interesting WesuggestthatadifferencebetweentheamountofCPviolationasmeasuredonthesurfaceofthe Earth and on the surface of the Mooncouldalsolargerthaninorbit.

•  On the Moon, the gravitational accelerationgMoon = 1.622 m/s2 is only 16.54% of thecorrespondingoneonEarth.Suchadifferenceshould be extremely usefu l to ourinvestigationonthecontributionofgravitytothemixingintheneutralkaonsystem.

•  A directmeasurement of the flux of protonson the lunar surface has not beenmade yetbutAckermannetal.have fit thedataof thegammaalbedofromtheMoonsurfaceduetothe incoming proton flux finding this lastequal, inside a 10% error, to the onemeasuredbyAMS2andPamela.

AcrudeglancewithAMS2

conclusions•  We have proposed a possible test of the gravitational behavior of

antimatterbymeasuringtherateof theCPviolatingdecay inspace.Weestimatethat:

•  5σ measurement of a possible change in the CP violation parameter εcould be obtained within some years, depending on the detectionefficiency,ifoneplacesadetectorwithafewcmthicktungstentarget,a1m diameter by 1m deep tracking region, amagnetic field for charged-particle identification, time-of-flight counters, and electromagneticcalorimeters for energy measurements, on a Leo or better onGeostationary orbit. Even better could be an experiment on theMoon.AnydifferencebetweentheamountofCPviolation inorbitwithrespecttothelevelofCPviolationontheEarth’ssurfacewouldbeanindicationofthe nature of the gravitational interaction between matter andantimatter. A positive result may offer an explanation for the cosmicbaryonasymmetryandmayoffera contribution to theobservedeffectsthoughttocomefromdarkmatteranddarkenergy.AfirstGlancecanbepossibleusingAMS2data.


April121961

ACKNOWLEDGMENTS•  THANKSTO:•  GabrielChardinCEASaclayFrance•  ErasmoRecamiUniversityofMilanItaly•  GianlucaLamannaINFNBARIItaly•  Thomasj.Phillips-DukeUniversityNCUSA•  PatriziaCaraveoINAFMilanoItaly•  DanKaplanIllinoisInstituteofTechnologyUSA•  HenryJ.FrischUniversityofChicagoUSA•  LucianoRistoriFermilabUSA

12/04/18 52g.m.piacentino

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