SwamplandPerspectiveonEarlyandLatetimeCosmology

CumrunVafaHarvardUniversity

Cosmic ControversiesUChicago

Oct.6,2019

Swampland Perspective onEarly and Late time Cosmology

Cumrun VafaHarvard University

Cosmic ControversiesUChicago

Oct. 6, 2019

Basedon6papers

CaneveryconsistentQuantumFieldTheoryariseasalimitoflowenergyofsomequantumgravitationaltheory?

CaneveryconsistentQuantumFieldTheoryariseasalimitoflowenergyofsomequantumgravitationaltheory?

No!NotaccordingtoStringtheory!

CaneveryconsistentQuantumFieldTheoryariseasalimitoflowenergyofsomequantumgravitationaltheory?

No!NotaccordingtoStringtheory!

Example:N=4SYMind=4forarbitrarygaugegroupGisaconsistentQFTbutifrank(G)>22itcannotariseaspartof4dQuantumsupergravity.

CaneveryconsistentQuantumFieldTheoryariseasalimitoflowenergyofsomequantumgravitationaltheory?

No!NotaccordingtoStringtheory!

Example:N=4SYMind=4forarbitrarygaugegroupGisaconsistentQFTbutifrank(G)>22itcannotariseaspartof4dQuantumsupergravity.

Swamplandprogram:DelineateconditionstodistinguishgoodQFT’s(`Landscape’)frombadones(`Swampland’)[V.,2005]

InthistalkIreviewSwamplandconditionswhichrelatetocosmologyandtheirconsequences.

Bothearly(inflation)andlateuniverse(darkenergy)descriptionsoftheuniverseseemtorequireunderstanding

𝜑

𝑉

∫ 𝑔%& 𝜑 ∇𝜑%∇𝜑&𝑑)𝑥

𝑑𝑠,- = 𝑔%& 𝜑 𝑑𝜑%𝑑𝜑&

𝑂(1)

DistanceConjectureisamanifestationofStringdualities[Ooguri,V.;2006]

Tower of light modes

𝑚

𝜑

𝑚~𝐴𝑒789

𝛼: 𝑂(1)𝜑

𝑉 𝜑 → 0 as𝜑 → ∞

𝑉

𝜑

General String compactification analysis suggests:

𝑉@

𝑉 AB

≥23

𝑉

𝜑

𝑉~𝑚F~𝑒7F(89)

𝑉~𝑒7G9 for 𝜑 ≫ 1

𝑉 𝜑 → 0 as𝜑 → ∞

𝑉

𝜑

𝑑𝑆

𝐴𝑑𝑆

𝑈𝑛𝑠𝑡𝑎𝑏𝑙𝑒

No model of dark energy is stable!

ForAdSwehaveverysimpleconstructions.Infactmanysupersymmetricexamples.AdS/CFT,etc.

FordSthestoryisverydifferent.Currentlywehavenotevenasingleexamplewherewecancontroltheapproximation.ThebestavailableideasareKKLTscenarioandLVSscenariowhichproposewaysonecangoaboutconstructingsolutions,butduetotheircomplexitynotevenoneexamplehasbeenactuallyconstructed.WearenotsureifdSexistsandiftheydo,howunstabletheymaybe.

𝑉@ > 𝑐𝑉

?

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

≥ -\

PresentandFuture:

Assuming(2)wecanonlybeinrollingpotentialsituation.Moreover,inashorttimewewillrollmorethanMpleadingtoaphasetransition.Estimatedtime

Assuming(3)(TCC)itcanbeeithertheabovescenario,orshort-livedmeta-stabledS:

𝜏 < 𝑁1

𝐻_(𝑁~30)

𝜏 <1Λ

ln1Λ

~2 𝑇𝑦𝑟𝑠

Eitherversionoftheconjectureexplainsthecoincidenceproblem ofwhythetimescaleassociatedtomeasuredvalueofthedarkenergy

isclosetothecurrentageoftheuniverse.Thelifetimeoftheuniversecannotbemuchlonger.Soinanyuniversewheredarkenergyismeasured(i.e.isasizablefractionofenergybudget)theassociatedtimescaleisthesamescaleastheageofthatuniverse (e.g.itcouldnothavebeendiscoveredmuchlater,becausetheuniversewouldhavedecayedortransitionedtoanewphase!).

𝜏~1Λ

Swamplandideasmotivatetakingrollingscalarfieldsmoreseriouslyasasourceofdarkenergytoday.

Thescalarfieldsshouldbepartofthedarksectorandinteractveryweaklywithvisiblesector(similartotherestofdarksector).Moreoveritshouldcouplestronglyatleasttoafractionofdarksectorandasitrolls,itshouldleadtoafadingofdarkmatter,duetotheSwamplanddistanceconjecture.

- Dark sector

𝑒7G̃9

𝜑_

𝜌hi 9j9__𝑒7G̃9𝜌hi

_

Fading DM model

𝑉

𝜑

~𝑒7G9

Improves,butdoesnotresolvetheH0tension.H0=69.1km/s/Mpc

Darkmatterfadingby10%beginningaroundredshiftz=15.

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\_

ConclusionSwamplandConditionscanleadtopotentiallyobservableconsequencesforcosmology.

Broadlytheseideassuggestpositiveenergyinthecontextofquantumgravityleadtolocalandglobalinstabilities—explainscoincidenceproblem.

ModelsofrollingscalarfieldsinteractingwithDM(leadingtofadingDM)shouldbetakenseriously.

Inflationisintension—Worthwhilestudyingalternatives.