Cosmic Controversies UChicago€¦ · Cumrun Vafa Harvard University Cosmic Controversies UChicago...
Transcript of Cosmic Controversies UChicago€¦ · Cumrun Vafa Harvard University Cosmic Controversies UChicago...
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SwamplandPerspectiveonEarlyandLatetimeCosmology
CumrunVafaHarvardUniversity
Cosmic ControversiesUChicago
Oct.6,2019
Swampland Perspective onEarly and Late time Cosmology
Cumrun VafaHarvard University
Cosmic ControversiesUChicago
Oct. 6, 2019
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Basedon6papers
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CaneveryconsistentQuantumFieldTheoryariseasalimitoflowenergyofsomequantumgravitationaltheory?
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CaneveryconsistentQuantumFieldTheoryariseasalimitoflowenergyofsomequantumgravitationaltheory?
No!NotaccordingtoStringtheory!
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CaneveryconsistentQuantumFieldTheoryariseasalimitoflowenergyofsomequantumgravitationaltheory?
No!NotaccordingtoStringtheory!
Example:N=4SYMind=4forarbitrarygaugegroupGisaconsistentQFTbutifrank(G)>22itcannotariseaspartof4dQuantumsupergravity.
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CaneveryconsistentQuantumFieldTheoryariseasalimitoflowenergyofsomequantumgravitationaltheory?
No!NotaccordingtoStringtheory!
Example:N=4SYMind=4forarbitrarygaugegroupGisaconsistentQFTbutifrank(G)>22itcannotariseaspartof4dQuantumsupergravity.
Swamplandprogram:DelineateconditionstodistinguishgoodQFT’s(`Landscape’)frombadones(`Swampland’)[V.,2005]
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InthistalkIreviewSwamplandconditionswhichrelatetocosmologyandtheirconsequences.
Bothearly(inflation)andlateuniverse(darkenergy)descriptionsoftheuniverseseemtorequireunderstanding
𝜑
𝑉
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∫ 𝑔%& 𝜑 ∇𝜑%∇𝜑&𝑑)𝑥
𝑑𝑠,- = 𝑔%& 𝜑 𝑑𝜑%𝑑𝜑&
𝑂(1)
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DistanceConjectureisamanifestationofStringdualities[Ooguri,V.;2006]
Tower of light modes
𝑚
𝜑
𝑚~𝐴𝑒789
𝛼: 𝑂(1)𝜑
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𝑉 𝜑 → 0 as𝜑 → ∞
𝑉
𝜑
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General String compactification analysis suggests:
𝑉@
𝑉 AB
≥23
𝑉
𝜑
𝑉~𝑚F~𝑒7F(89)
𝑉~𝑒7G9 for 𝜑 ≫ 1
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𝑉 𝜑 → 0 as𝜑 → ∞
𝑉
𝜑
𝑑𝑆
𝐴𝑑𝑆
𝑈𝑛𝑠𝑡𝑎𝑏𝑙𝑒
No model of dark energy is stable!
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ForAdSwehaveverysimpleconstructions.Infactmanysupersymmetricexamples.AdS/CFT,etc.
FordSthestoryisverydifferent.Currentlywehavenotevenasingleexamplewherewecancontroltheapproximation.ThebestavailableideasareKKLTscenarioandLVSscenariowhichproposewaysonecangoaboutconstructingsolutions,butduetotheircomplexitynotevenoneexamplehasbeenactuallyconstructed.WearenotsureifdSexistsandiftheydo,howunstabletheymaybe.
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𝑉@ > 𝑐𝑉
?
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Threepossibilities,studiedsofar,forVinside:1) Norestrictions.(Unnatural,givenvery
specificboundarybehaviorforVleadingtoinstability)
2) ThedSSwamplandconjecture:EitherVissufficientlyunstable(V”/V<-c’)or |V’|>cVeverywhere(withc,c’O(1)).[OOSV],[KG,OPSV]
3) Trans-PlanckianCensorshipConjecture(TCC):sub-PlanckianmodescannotcrosstheHubblehorizon[BV]: 𝑎S
𝑎%⋅ 𝑙U <
1𝐻S
Explainstheasymptoticbehavior⇒ YZ
Y [B
≥ -\
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PresentandFuture:
Assuming(2)wecanonlybeinrollingpotentialsituation.Moreover,inashorttimewewillrollmorethanMpleadingtoaphasetransition.Estimatedtime
Assuming(3)(TCC)itcanbeeithertheabovescenario,orshort-livedmeta-stabledS:
𝜏 < 𝑁1
𝐻_(𝑁~30)
𝜏 <1Λ
ln1Λ
~2 𝑇𝑦𝑟𝑠
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Eitherversionoftheconjectureexplainsthecoincidenceproblem ofwhythetimescaleassociatedtomeasuredvalueofthedarkenergy
isclosetothecurrentageoftheuniverse.Thelifetimeoftheuniversecannotbemuchlonger.Soinanyuniversewheredarkenergyismeasured(i.e.isasizablefractionofenergybudget)theassociatedtimescaleisthesamescaleastheageofthatuniverse (e.g.itcouldnothavebeendiscoveredmuchlater,becausetheuniversewouldhavedecayedortransitionedtoanewphase!).
𝜏~1Λ
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Swamplandideasmotivatetakingrollingscalarfieldsmoreseriouslyasasourceofdarkenergytoday.
Thescalarfieldsshouldbepartofthedarksectorandinteractveryweaklywithvisiblesector(similartotherestofdarksector).Moreoveritshouldcouplestronglyatleasttoafractionofdarksectorandasitrolls,itshouldleadtoafadingofdarkmatter,duetotheSwamplanddistanceconjecture.
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- Dark sector
𝑒7G̃9
𝜑_
𝜌hi 9j9__𝑒7G̃9𝜌hi
_
Fading DM model
𝑉
𝜑
~𝑒7G9
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Improves,butdoesnotresolvetheH0tension.H0=69.1km/s/Mpc
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Darkmatterfadingby10%beginningaroundredshiftz=15.
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SwamplandConjecturesandInflation:Inflationnotruledoutbuttypicalscenariosseematleasthighlyfinetuned!Thedistanceconjectureleadstopredictionthatwecannothavenaturalarbitrarilylargefieldinflation,becausewegetatoweroflightstatesandthatinterfereswithinflation.Multi-fieldmayovercomethis.(2)Slopeconjecture:ForexamplePlateaumodels,c<0.02leadtorathersmallnumbers.
(3)TCC: 𝑉 ≲ 𝑀Un
o\ 𝑇_𝑇pq
-\~ 10r𝐺𝑒𝑉 )
𝜖 < 107\u
𝑟 < 107\_
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ConclusionSwamplandConditionscanleadtopotentiallyobservableconsequencesforcosmology.
Broadlytheseideassuggestpositiveenergyinthecontextofquantumgravityleadtolocalandglobalinstabilities—explainscoincidenceproblem.
ModelsofrollingscalarfieldsinteractingwithDM(leadingtofadingDM)shouldbetakenseriously.
Inflationisintension—Worthwhilestudyingalternatives.