Conformal Ghosts on the Sphere
Von der Fakultät für Mathematik und Physik
der Gottfried Wilhelm Leibniz Universität Hannover
zur Erlangung des Grades einer
Doktorin der Naturwissenshaften
Dr. rer. nat.
genehmigte Dissertation
von
Dipl. Phys. Kirsten Vogeler
geboren am21. August 1978 in Hanau
2010
Koreferent: Prof. Dr. Maro Zagermann
Tag der Promotion: 16.07.2010
Zusammenfassung
IndieserArbeit behandele ih dieVerbindungvonGeometrie undlogarithmish konformen
Feldtheorien. Dabeibetrahte ih zwei vershiedene geometrishe Situationen: inTeil Idas
topologishe A-Modell mit Einbettungsabbildung
x : R × S 1 → CP 1
und inTeil IIkonforme, fermionishe Geister aufdemTorus.Das A-Modelllässt sih ineineForm bringen,inderdasPfadintegraleine
δ
-Distribution aufdemModulraumderInstantonenist. Integriert mandieAbhängigkeitvonS 1
heraus,er-hältmaneineMorsetheorieaufderuniversellenÜberlagerung
L CP 1
desLoop-Raumes. Deren Niedrigenergie-Zustandsräume lassen sih in Zellen dieser Mannigfaltigkeit störungstheo-retishbestimmenunddurhDarstellungsräumedesChiralendeRham-Komplexesbeshrei-
ben. Unter der Annahme, dass die Darstellungstheorien des A-Modelles und des Chiralen
de Rham Komplexes übereinstimmen, betrahte ih im Folgenden den Chiralen de Rham-
Komplex. DieZustandsräumesindlokale,induzierteDarstellungenderSymmetrie,diedurh
das Gradientenfeld der Morsefunktion erzeugt wird. Entsprehend einer Hypothese von E.
Frenkel,A.LosevundN.NekrasovführteineVerallgemeinerungdieserlokalenDarstellungen
als Distributionenauf
L CP 1
zu quantenexakten Zuständender Theorie. Aufdiesen Zustän- denmussderHamiltonoperatordurhzusätzliheTermekorrigiertwerden. IhdiskutieredieDarstellungstheoriederquantenexaktenZustände undbestimmedieDeformationstermedes
Hamiltonoperators. Ihzeige, dassdiese eine geometrishe Deutungals Kohomologieopera-
toren in einem Komplex global erweiterter lokaler Darstellungsräume haben. Zuletzt zeige
ih,dassdenzusätzlihenTermenimHamiltonoperatorderMorsetheorieeinelogarithmishe
Erweiterung deshiralende Rham-Komplexesentspriht.
Diekonformen,fermionishenGeisterausTeilIItransformierensihinirreduziblenDarstel-
lungen der Monodromiegruppe
Z 2
. Ih zeige, dass die durh sie beshriebene konforme Feldtheorie logarithmish erweitert werden muss, sobald man zu den Darstellungen derMonodromiegruppe Felder assoziiert, die sih frei auf dem Parameterraum
CP 1 \ {0, 1, ∞ }
bewegen. DasTripletmodell stellt eineminimale logarithmishe Erweiterung dieserTheorie
dar undbildetdieGrundlagemeinesletztenKapitels. Darin drükeih diespektraleKurve
der
SU (2)
-Seiberg-Witten Theorie durh dieCharaktere desTripletmodelles aus, und führe ebenfallsdasPräpotential aufdiesesModellzurük,indem ihes alsFunktiondesModulusderspektralen Kurve gewinne.
Schlagworte:
Nihtlineares Sigma Modell, Logarithmish Konforme Geister, Seiberg Wit- tenTheorieAbstract
This thesis is about the relation of geometry and logarithmi onformal eld theories. I
onsidertwodierentgeometri settings: inpartIthe topologialA-modelwithembedding
x : R × S 1 → CP 1
,and inpartIIonformal, fermioni ghosts onthetorus.The A-model an be transformed suh that the path integral yields a
δ
distribution on the moduli spae of instantons. Integrating out the dependeny onS 1
, one obtains Morsetheoryon theuniversalover
L CP 1
of loop spae. Itslow-energy statespae an be derived perturbatively in ells of this manifold, and an be modelled by therepresentations of thehiral de Rham omplex. Assuming that the representation theory of the A-model and
the hiral de Rham omplex are idential, I onsider the hiral de Rham omplex in the
following. Thestatespaes areloal,induedrepresentationsofthesymmetrygeneratedby
thegradient vetor eld ofthe Morsefuntion. Aording to a onjetureof E. Frenkel, A.
Losev and N. Nekrasov, a generalization of these loal representations as distributions on
L CP 1
leads to nonperturbative statesof thetheory. On thesestates, theHamiltonian must beorretedbyadditionalterms. Idisusstherepresentation theoryofthenonperturbativestates and determine the terms whih deform the Hamiltonian. They have a geometri
signiane asohomology operators inaomplex ofglobally extendedloalrepresentation
spaes. Eventually, I prove that a logarithmi extension of the hiral de Rham omplex
orrespondsthe additional termsintheHamiltonian.
The onformal, fermioni ghosts ofpart IItransform inirreduible representationsof the
monodromygroup
Z 2
. Ishowthat theonformaleld theoryofthese elds hasto beloga- rithmially extended assoon asthe representations ofthe monodromygoup are allowed tomove freely on the parameter spae
CP 1 \ {0, 1, ∞ }
of the torus. The triplet model onsti-tutesaminimallogarithmiextensionofthistheoryandisfundamentalformylasthapter.
ThereinIobtainthe spetralurveof
SU (2)
Seiberg-Wittentheoryintermsof haratersof thetripletmodel. Further,Itrae baktheprepotential to thatmodelbyexpressing itasafuntion ofthe torus modulus ofthespetralurve.
Key words:
NonlinearSigmaModel,LogarithmiConformalGhosts,SeibergWittenTheoryContents
1 Introduction 1
I Supersymmetric Ghosts with Values on the Sphere 5
2 Morse Theory 7
2.1 ThePath IntegralPoint ofView . . .
7
2.1.1 Making CPT Breaking andLoalization Manifest. . .
9
2.1.2 TheInstanton Moduli Spae . . .
9
2.2 TheCanonial Point ofView. . .
12
2.2.1 Onthe Cohomology. . .
13
2.2.2 Implementing CPT Breaking and Loalization . . .
14
2.2.3 TheInstanton Moduli SpaeRevisited . . .
15
2.2.4 TheOut-States . . .
17
2.3 Summaryof the Constraints on
X
. . . . . . . . . . . . . . . . . . . . . . . . . . .19
2.4 MorseTheory on
X = CP 1
. . .20
2.4.1 Polynomial Distributions on
CP 1
. . .23
2.5 Interpretation oftheExtension . . .
29
2.6 Generalizationto General Target Manifolds . . .
32
2.6.1 ThePerturbative State Spaes . . .
32
2.6.2 TheGrothendiek-Cousin Operators . . .
33
3 From the A-Model to Morse Theory 35
3.1 MassagingtheA-model . . .36
3.2 TheMorse TheorybehindtheA-model . . .
39
3.2.1 ThePotential . . .
40
3.2.2 Isolatingthe CritialPoints . . .
41
3.3 Perturbative MorseDesription oftheA-Model . . .
42
3.3.1 ThePerturbative State Spaes . . .
43
3.3.2 ThePerturbative State Spaeon
g LX 0,k
. . . . . . . . . . . . . . . . . . .44
3.3.3 ThePerturbative State Spaeon
g LX ∞ ,k
. . . . . . . . . . . . . . . . . . .46
3.4 Relationto Conformal SupersymmetriGhosts . . .
46
3.4.1 TheConformal Supersymmetri
bc
-System. . . . . . . . . . . . . . . . .47
3.4.2 Identifying theState Spaes . . .
51
3.4.3 What iftheGauge Field isAbsent? . . .
52
3.5 Conformal Supersymmetri Ghosts on
CP 1
. . .54
3.5.1 TheChiral de RhamComplex . . .
54
3.6 Beyondthe Perturbative Representations . . .
59
3.6.1 Existeneof Grothendiek-CousinOperators. . .
59
3.6.2 Chiral Bosonization . . .
61
3.6.3 TheGCOsand theCohomology Interpretation . . .
67
3.6.4 Conlusion . . .
70
4 The A-Model beyond Topology 71
4.1 TheMethod ofLogarithmi Deformation . . .71
4.1.1 Extension ofthe Fields . . .
71
4.1.2 Extension ofthe Representation Theory . . .
72
4.1.3 TheFermioni
bc
-System . . . . . . . . . . . . . . . . . . . . . . . . . . .73
4.2 Introduing the GCOs. . .
74
4.2.1 Extension ofthe Fields . . .
74
4.2.2 Notes ontheSymmetries . . .
76
4.2.3 ExeptionalLogarithmi Partners . . .
76
4.2.4 OntheNeessityto Deformthe Fermions . . .
77
4.2.5 Extension ofthe State Spae . . .
77
4.2.6 Conlusion . . .
80
5 Summary and Conclusion 81 II Conformal Fermionic Ghosts on the Torus 85 6 Motivation 87 7 Fermionic Ghosts on Algebraic Curves 89
7.1 TheAlgebrai Surfaes . . .89
7.2 TheFermioni
bc
-SystemonT n,m
. . .90
7.2.1 AroundtheBranhPoints . . .
90
7.2.2 TheTwistedRepresentations . . .
92
7.2.3 Conlusion . . .
94
8 On Twist Fields and Torus Periods 95
8.1 TheLegendre Family . . .95
8.1.1 Relationto the LattieTorus . . .
96
8.1.2 A Dierential Equation forthe Periods . . .
97
8.1.3 Solutionsfor thePeriods . . .
98
8.2 LCFT-ationof theLegendre Family . . .
99
8.2.1 A HypergeometriEquation for the Twist Fields . . .
100
8.2.2 TheNeessityof a LogarithmiExtension . . .
101
8.3 TheTripletModel . . .
102
8.3.1 Symmetriesand Representations . . .
102
8.3.2 Realizationof the TripletModel . . .
105
8.3.3 Charaters . . .
106
9 Relation to Seiberg-Witten Theory 109
9.1 SomeWordsonSeiberg-Witten Theory . . .109
9.1.1 TheSpetralCurve ofSW Theory . . .
110
9.1.2 Modular Transformations . . .
110
9.2 TheSpetralCurve and TripletCharaters . . .
112
9.2.1 TheSpetralCurve inTerms of
τ
. . . . . . . . . . . . . . . . . . . . . .112
10 Conclusion 117 A Topological Field Theories 121 B From the Sigma to the A-Model 123
B.1 Twisting/Gauging theSigma Model . . .124
C The Toric CSbc - Unfinished 127
C.1 DeformationbyHolomorphiCompletion . . .127
C.2 TheCohomology OperatorsinLogarithmi Coordinates . . .
129
Notations
∗
Field-state-orrespondene,93≺ A ≺ B :
thesetA
isasubsetofodimensiononein thelosureofB
.˜1(z)
Thelogarithmipartnerof1(z )
,100∆ T (φ)
Conformalweightofφ
withrespet toT
δ
Grothendiek-Cousinoperator,32[ · , · ] , { · , · }
Gradedommutator,antiommutator[f ,g ] n (z )
Fieldintheoperatorprodutexpansion,72F
Disjointunion
| ˜0 〉
Logarithmipartnerof| 0 〉
,100| p 〉 ± , | p, ¯ p 〉 ± , | p, ¯ p 〉
ChargedrepresentationsoftheCSb,47,49,49A ǫ
RepresentationspaeoftheHeisenbergLie algebra,61CSb Conformalsupersymmetri
bc
-system,46C 0 CP 1 \ { ∞ }
C ∞ CP 1 \ {0}
C ×
Asaset
C × = C \ {0}
,asasymmetryf.pg.20C [ · ]
PolynomialsC (( · ))
FormalpowerseriesC [[ · ]]
PowerseriesD , D ∗
Complexunitdiskwith/without thepoint{0}
D , D ∗
Test funtions,distributions,23
D 0 , D ∞
Test funtionswithompatsupportinC 0 , C ∞ e, ¯ e
Extensionoftheperturbativerepresentations,34,extensioneld,72
E λ
Legendrefamily, 95F 0 , F ∞ , F × , F 1
∞
HolomorphirepresentationsoftheCSb,58,59f
(Logarithmially)extended eld,30,72 GCO Grothendiek-Cousinoperatorg , g O
GCO32,nontrivialpartofO = O + g O
30H
Globallydened states,28H λ
Non-unitaryHamiltonian,14H (pert)
PerturbativeHamiltonian,18H c,n in , H in
0,0 , H in
∞ ,0
PerturbativespetrumoftheTb,44,45,46H 0
Morsetheory/CSb,22,51H ∞
, 22,51Homogeneity
r
Aprefatorof| z | r , r ∈ R
in theeldexpansion,45,51i ifandonlyif
j ǫ
CurrentsoftheCSb,48j V ǫ , j A ǫ
VetorialandaxialurrentsoftheCSb,48J µ ǫ , J ǫ
CurrentsoftheHeisenbergLiealgebras,61J −
Currentofthebosonizedbosons, 64J N
CurrentmeasuringthegradingofN (p,p )
,65J(φ)
Chargeoftheeldφ
, 50Λ a,b
Basisofexteriorforms,23LX
LoopspaeofX
,39g LX
UniversaloverofLX
,40g LX n
SheetofLX
ing LX
,41g LX c,n
Desendingmanifoldwithritialpointx c
,44M ǫ (p) , ¯ M ǫ (p) , M ǫ (p, ¯ p )
ChargedrepresentationsoftheCSb,48,49M E
ParameterspaeoftheLegendreFamily96M (α,β)
Instantonmodulispae,10µ
TheA-model gauge-eldstrenght41,twisteldonthetorus100ν ǫ p, ¯ p
Highest weightstateoftheHeisenbergLiealgebra,61N (p ) , ¯ N ( ¯ p) , N (p, ¯ p)
Extendedrepresentationsofthebosonizedbosons,64N (p ), ¯ N ( ¯ p) , N (p, ¯ p)
Perturbativerepresentations , 66N L (p, ¯ p )
LogarithmiextensionofN (p − 1,p − 1)
,67O (naive)
Naiveoperator,30OPA OperatorProdutAlgebra
OPE OperatorProdutExpansion
PER Physially EligibleRepresentation,102
P 0
Polynomialof theeld modesintheCSb,54p, ˜ p
InpartII,projetionT n,m → CP 1 \ {e i }
, 89q
Bakgroundharge,anomaly,49Q ,Q 0
BRSThargeinMorsetheory,12,intheTb,37,53Q (z , ¯ z) , Q (z )
Superhargeeld, 49,itsholomorphipart,48SQM Superquantummehanis
Tb Topologial
bc
-system,ungauged38,gauged42V ǫ (r, z)
FieldsoftheHeisenbergLiealgebra,62X n
SubspaeX n ≃ X
ing LX n
,44X c,n X n ∩ g LX c,n
,44Introduction 1
Thisthesiswasinitiatedbymyinterestintherelationbetweengeometryandphysis. Itwas
sine I got to know the publiation of V.G. Knizhnik [Kni87 ℄ thatI wanted to investigate
the geometri signiane of theaspetswhih render aonformal eldtheorylogarithmi.
Knizhnikonsidersholomorphidierentialformsonalgebraisurfaeswhiharebranhed
overingsof
CP 1
andhaveaglobalZ n
monodromygroup. Thedierential formsanbeiden- tiedwithonformalfermioni ghosts,and themonodromygrouphasanindued ationontheseelds,whihthusfallinto
n
irreduiblerepresentations. Inthespiritofonformaleld theory(CFT),theserepresentationsarerealizedbyloatingtheonformalelds isomorphito the respetive highest weight vetors at the branh points. In mathematial terms, this
amounts to restriting the dierential forms to a neighborhood of a branh point and to
onsidering representation theorythereon.
Ifthealgebraisurfaehasbranhpoints
e i , i ∈ {1, . . . , 2N }
,N ≥ 2
,onemayturnthesurfaeintoafamilyoftopologiallyequivalentsurfaesbyallowing
2N − 3
branhpointstovaryoverCP 1 \ S 2N − 3
i = 1 {e i }
. This helps to extrat further geometri information, suh as degeneraies when branh points arefusing, or periods, whih satisfy dierential equations withrespetto theoating parameters.
Although my investigations started withthe work of Knizhnik, I will disuss this setting
inthe seond partof my thesis. There, I will onsider theCFT realization of both, degen-
eraies and periods for thealgebrai surfae being atorus. The dierential equationfor its
periods is realized as the nullstate ondition for the odd representation of the monodromy
group
Z 2
. Therefore, the four-point funtion of the so-alled twist eld orresponding to this representation is proportional to the periods of the torus. In partiular, it ontainslogarithmsand thefusionof twobranh points, whih issimulated bytheoperatorprodut
expansion(OPE)oftwosuhelds,yieldsa doubletrepresentationofthesymmetriesofthe
onformal fermioni ghost system. The Hamiltonian is not diagonalizable on this doublet,
whih signies that the CFT has to be extended to a logarithmi onformal eld theory
(LCFT). Theminimalisti way to dothis will leadto thetriplet model, asexplainedbyM.
Flohrin[Flo98 ℄.
Thissettinghasbeen the startingpointfor mypubliationwithM. Flohr[VF07℄. Asthe
torusisthespetralurveofpuregauge,
SU (2)
Seiberg-Wittentheory,wewantedtoexpress theprepotential intermsof haraters of the tripletmodel. Although we onlyobtained theprepotential in termsof the torus modulus, whih equals theratio of twist eld four-point
funtions, we have been able to determine the spetral urve by means of suh haraters.
Thiswill be the subjet ofhapter 9inpartII.
of E. Frenkel, A. Losev and N. Nekrasov [FLN06 , FLN08 ℄, who investigated Morse theory
and the topologial A-model beyond their topologial setors. What is implied by those
onsiderations?
(Cohomologial)topologialeldtheoriesdealwithglobalgeometriobjetsonmanifolds,
in partiular with dieomorphism invariants that are inthe ohomology of some nilpotent
operator
Q
, alled Behi-Rouet-Stora-Tyutin (BRST) harge due to its properties. It has an ation on the elds and state spaes of the theory and the elements in its ohomologylasses omprise whatis alledthe topologial setorofa eldtheory.
Underertainirumstanesaeldtheoryhasinaddition toitstopologial setorfurther
dynamial states and observables. While the ohomology of
Q
is invariant under dieo-morphisms, this is not the ase for the dynamial setor. Hene, the dynamial degrees
of freedom should in priniple desribe part of the loal geometry of the target or domain
manifold.
In[FLN06 ℄,Frenkel, LosevandNekrasovonsiderthesituationdesribedaboveforMorse
theorywitharstorderLagrangian onaKählermanifold
X
withsaled metriλg, λ ∈ R > 0
. The perturbative spetrumof this theory inludes topologial as well as dynamial states.If
X
is supplemented with an additional struture, these states have their support on the desending manifolds of the gradient vetor eld of the Morse funtion. Moreover, thesubmanifoldsyield adisjoint overof
X
,and sodothe perturbative state spaes.The loal geometry of
X
an be aessed employing the dynamial states. Forλ → ∞
,the Hamiltonian beomes the Lie derivative in diretion of the gradient vetor eld of the
Morse funtion. The perturbative state spaes whih survive that limit turn into loally
dened indued representations of the symmetry generated by the gradient eld. This is,
metaphorially, what an observer loated on a desending manifold would expet to see.
However, Frenkel,Losevand Nekrasovlaimthatthere arenonperturbative eets through
whih the observer obtains additional insights into the loal representations of the Hamil-
tonian on
X
. They propose that the nonperturbative state spaes are obtained by ex- tending the perturbative state spaes as distributions toX
and their analysis shows thatthethus globalizedrepresentations aretheloalohomology groupsinaomplex alledthe
global Grothendiek-Cousin omplex, [Kem78℄. This omplex has a ohomology operator,
theGrothendiek-Cousinoperator(GCO),whihompoundstheloalrepresentationspaes
and appears as an additional term in the Hamiltonian. The observer is thus onfronted
withaHamiltonianwhihannot be diagonalizedonall dynamialstatesasituation well
knownin thetheory oflogarithmi CFTs.
My initial interest in thework of Frenkel, Losevand Nekrasov [FLN06℄ arose from their
proposal that the topologial A-model in the large volume limit is an LCFT beyond its
topologial setor. In [FLN08 ℄, they reduethe A-modelwithembedding
x : R 1 × S 1 → CP 1
to the Morse theory of [FLN06 ℄ by integrating out the dependene on
S 1
. In partiular,one an derive the perturbative state spaes and it appears that they an be modelled by
representationspaesoftheonformalsupersymmetrighosts(CSb)withtargetspae
CP 1
. Itis nowsuggestive to assumethatat leastthe representation theoryof theA-modelinthelargevolume limitequalsthatoftheCSbandthetheoriesan,aordingly,besubstituted.
Furthermore, Frenkel, Losev and Nekrasov propose thedeformation of the Hamiltonian,
but do not analyze the extension of therepresentation spaes indetail. Moreover, in order
toprovetheironjeturethattheA-modelisanLCFTinthelargevolume limitandbeyond
its topologial setor, it is not suient to onsider the underlying Morse theory. A loga-
rithmi deformation oftheCSb hasto befound,whih yieldstheorretextensions ofthe
perturbative representation spaes and addsthe deformation terms to the Hamiltonian. It
is only then, thatthe Grothendiek-Cousin operators an be interpretedas thezero modes
ofthelogarithmi improvement termswhihdeform theenergy momentumtensor. Partsof
those onsiderations have been addressedinmyseondpubliation withM. Flohr[VF09℄.
Asmentionedabove,thisthesishastwoparts,thersttreatsthelogarithmiextensionof
theCSbunderlyingtheA-model,theseondisaboutfermionighostsonthetorusandtheir
relationtoSeiberg-Wittentheory. BeforeIstartwithanoutline,Iwillbrieyommentonthe
appendix,whihservestosupplementthemainpart. InappendixAIsummarizeandspeify
the basi ingredients of a topologial eld theory [BBRT91 , Wit82 , Wit88a , Wit88b℄. In
appendixB.1IbrieyexplainhowthetopologialA-modelisobtainedbytwistingan
N = 2
supersymmetrisigmamodelandnotedownthesupersymmetryofthistheory[Mar05℄. The
last appendix Cisthe foundation of another publiation,wherein Istudy thepossibilityto
generalize the approah ofFrenkel,Losevand Nekrasov[FLN08 ℄,bywhih theydeform the
Hamiltonian oftheA-model, toa deformation ofthe assoiated CSb.
Part I
Inthefollowinghapter2,IwillstartwithadisussionofMorsetheory. Therein,thegeometri origin of the deformation operatorsis disussed and theonditions on thetarget
spaemanifoldarexed. ThishapterfollowsthepubliationofFrenkel,LosevandNekrasov
[FLN06 ℄, but some subtle pointsare treated inmore detail. Inpartiular this onerns the
extension ofthe perturbative representation spaes. Iwillpropose analternative ansatz for
the extension, whih relies on a priniple bywhih I an enlarge the representation spaes.
Thisansatz isappliable intheontext ofthe A-model.
Inhapter3,IwillintroduetheA-modelwithtargetspae
CP 1
andtakethelargevolume limit. ReduingthethusobtainedtheorytoMorsetheory,Iwillderivetheperturbativestatespaes andexplainwhytheyan be modelled bytheCSb. BeausetheA-modelisdened
on
CP 1
,itisneessarytomakeharttransitions. FortheCSb,thesetransitionsaredened through the hiral de Rham omplex, whih I will also introdue. My method to derivethedeformation of the Hamiltonian diers again fromthat ofFrenkel, Losev andNekrasov
thattheholomorphiandanti-holomorphihalves oftheCSbareonsideredtogether,not
onlybeause ofanomalies ourringbutalsobeausethe GCOsareomposedofbothparts.
Indeed, I will explain that this omposition onstrains the representation spaes and the
symmetries ofthe theory.
Having determinedthe perturbativerepresentationspaes, theirextensions, andtheGro-
thendiek-Cousin operatorsthat mediate between them, Iwill thenmove bak fromMorse
theory to the onformal eld theory. In hapter 4, I will use the method of Fjelstad et
al. [FFH
+
02 ℄ to deform the CSb logarithmially. I will do that in suh a way that the
representation spaesareextendedonsistently andthattheGCOsareaddedto theHamil-
tonian. Thishasan eet on the operator produt algebra of theelds, but neitheron the
supersymmetrynor the onformalsymmetryofthe CSb.
I willonlude this partof the thesiswitha briefsummaryand disussioninhapter 5.
Part II
Inparttwo Iwillonentrateonthefermionionformalghosts onbranhed over-ingsof
CP 1
[Kni87 ℄. Afterabriefmotivationinhapter6,Iwillspeifythealgebraisurfaes under onsideration and introdue theonformal ghosts inhapter 7. Sine they will havenontrivial operator produtexpansionsin a neighborhood of a branh point it is neessary
to extend therepresentation spaes by therepresentationsof themonodromygroup.
In thethe subsequent hapter8, Iwill derive bygeometri argumentsthat thefermioni
ghosts on thetorus neessarilyomprise a logarithmi onformaleld theory. The minimal
versionis thetripletmodel[Flo98 ℄,whih Iwill introdue inhapter8.3.
In the last hapter 9, I will explain how the spetral torus of puregauge Seiberg-Witten
theory an be obtained from ertain haraters of the triplet model and note down an
expressionoftheprepotentialwhihisgivenompletelyintermsofquantitiesofthisLCFT.
The thesis will be onluded with a summaryand a disussion of open questions in the
last hapter 10.
I
Supersymmetric Ghosts with Values
on the Sphere
Morse Theory 2
Thishapterhasthreeparts. MystartingpointwillbeMorsetheoryonageneralRiemannian
surfae
X
withsaled metriλg
and sympletiformω
.Firstly,IwillpreparethetopologialsetorofthistheorybybreakingCPT invarianeand
by making loalization on the instantons expliit. This amounts to onseutively putting
onstraintson
X
. TheonstraintswillbesuhthattheinstantonsetorsarewelldenedandthatthegradienteldorrespondingtotheMorsefuntiondeomposes
X
intosubmanifolds, to eah of whih one an perturbatively assoiate a state spae. Among those, there areexited stateswhihare not saledout inthelarge volume limit
λ → ∞
.Frenkeletal.proposed[FLN06 ℄thatthestatespaesinthelimit
λ → ∞
,whengeneralized as distributions onX
, omprise the nonperturbative low energy spetrum. In setions 2.4 and2.5IwilldisusssomeonsequenesofthisassumptionforMorsetheoryonCP 1
,mainly following their publiation but also with an additional disussion of theohomology of thesuperharge,aswellasadierentmethodforextendingthestatespaesasdistributions. The
most important observation will be that observables whih inlude exterior derivatives are
nolongerdiagonalizable onallstates. Inpartiular,this onernstheHamiltonianandthus
draws asimilarityto logarithmi onformaleld theories. Rather, those operators intermix
the state spaes whihformerlyhave beenloatedindierent harts.
Finally, I will disuss the physial and geometrial meaning of this sort of non-loality,
whih isdue tothe non-topologial states.
Thishapterwillbeonludedwithageneralizationofthetoymodeltoalassofmanifolds
X
and will be the basis for an understanding and analysis of the Morse theory underlyingthetopologial A-model. Myexplanationsrely mostlyon[FLN06, BBRT91, Wit82℄.
2.1 The Path Integral Point of View
In terms of the strutures just introdued, the Morse theory I will onsider onsists of a
Riemannian surfae
X
, a smooth embeddingx : Σ ⊆ R → X
, its Grassmann valued super-partner
ψ
and anotherGrassmann valued quantityπ
,whih istheonjugate momentumofψ
. The Eulidean metrig
onX
is saled bysome parameterλ ∈ R > 0
and, without lossof generality, Ixa onnetionD
to be theLevi-Civitaonnetion, dened withpositivesign on∂
∂x µ : D ν ∂
∂x µ = ∂x ∂ λ Γ λ
νµ
.Let
f : X → R
be Morse, i.e.single valued and withisolated ritial pointsx c : d f (x c ) = 0
,anddenote furtherby
D t ψ µ = dψ dt µ + Γ µ
λσ dx λ
dt ψ σ
the pullbakofD
toΣ
andby∇ µ f : = g µν ∂ ν f
thegradient of
f
. Inloaloordinates, the ation Iaminterested inisS λ = Z
Σ
³ 1 2 λg µν
dx µ dt
dx ν dt + 1
2 λg µν ∂ µ f ∂ ν f + iπ µ ∇ t ψ µ − iπ µ ¡
D α ∇ µ f ¢
ψ α + 1
2λ R αβ µν π µ π ν ψ α ψ β ´ dt .
(2.1.1)
In thefollowing setions I will extrat its topologial setor, seleting eitherthe instantons
or anti-instantons and by speifyingseveralonditions on
X
.Sine
df (x c ) = 0
,theHessianH(x)[γ] : = D γ (d f )(x)
,γ ∈ T x X
doesnot depend on thehoieof the onnetion at a ritial point
x c
. In loal oordinates it readsH µν (x c ) = ∂ µ ∂ ν f (x c )
.There existsa basis
e µ
of tangent vetors atT x c X
in whih it is diagonal with eigenvaluesκ c µ
:H (x c ) e µ = κ c µ e µ
. The onditionthattheritial points areisolatedis equivalent totheonditionthat
H(x c )
hasnozeroeigenvalues. SinetheHessiandoesnotdepend ontheonnetion, itisreasonable to dene an index foreveryritial point
ind(x c ) = #{µ : κ c µ < 0} , (2.1.2)
whih isatopologial invariant.
In order to see what the lassial solutions are, I will for a moment onentrate on the
bosoni part. One an apply the so-alled Bogomlny trik to nd theabsoluteminima of
theation:
S bos = Z
Σ
à λ 2
µ dx µ dt ∓ ∇ µ f
¶ 2
± λ df dt
!
dt . (2.1.3)
Sineit waspositivesemi-denite before, Iobtain alower bound
S bos ≥
¯ ¯
¯ ¯ Z
Σ
d f
¯ ¯
¯ ¯ , (2.1.4)
whih issatisedbythe gradient trajetories
dx µ
dt ± ∇ µ f = 0 . (2.1.5)
Thesearethelassial bosoni solutions to
δS = 0
. There arethree kinds,depending ontheboundaryonditions. The vauumongurations aresolutions of
dx µ
dt = 0 ∧ ∇ µ f (x) = 0 , (2.1.6)
whih issatisedbyonstant loops,i.e. theritialpoints
x c
. Ifthere existsmorethan oneritialpoint, say
{x + , x − }
,therearealsoinstanton (−∇ f
)andanti-instanton ongurations (+∇ f
) :dx µ
dt ± ∇ µ f (x) = 0 , x( ±∞ ) = x ± (2.1.7)
where w.l.o.g. I xed some initial and nal time. From (2.1.4) one an onlude that the
instantonssatisfy
f (x + ) > f (x − )
and the anti-instantonsf (x + ) < f (x − )
.2.1.1 Making CPT Breaking and Localization Manifest
The anti-instantons an be exluded from the lassial minima by subtrating
λ R
d f
fromthe ation (2.1.1). This term does not depend on the metri and is hene topologial. It,
however, breaksCPT invariane asonewould expetfor atheorywithout anti-instantons.
1
Inorderto maketheloalizationpropertymanifest,Imassagetheation
S − λ R
df
intoarstorderform,byintroduingaLagrangianmultiplier
p µ
. Viewedaspartoftheintegration kernelexp{ − S}
inthe path integral, I maynow onsider, equivalently to (2.1.1):S λ = Z
Σ
³
− ip µ
µ dx µ
dt − g µν ∂ ν f
¶ + 1
2λ g µν p µ p ν
+ iπ µ ¡
D t ψ µ − (D α ∇ µ f )ψ α ¢ + 1
2λ R αβ µν π µ π ν ψ α ψ β ´ dt .
(2.1.8)
Inthelimit
λ → ∞
,theintegralkernelturnsintoaδ
distributiononinstantonmodulispae, whih makes loalization expliit. Indeed, for niteλ
, the instantons still ontribute witha weight fator
e − 2λ | f (x + ) − f (x − ) |
to orrelation funtions, but forλ → ∞
their ontribution disappears. On the ontrary, the instantons ontribute witha onstant weight fator1
forany value of
λ
.Let
v µ (x) : = ∇ µ f (x)
be the vetor eld assoiated withf
andp µ ′ : = p µ + Γ λ µν ψ ν π λ
. Theation inthe large volume limitan nowbewritten as:
S ∞ = − i Z
Σ
µ p ′ µ
µ dx µ dt − v µ
¶
− π µ
µ dψ µ
dt − ψ α ∂ α v µ
¶¶
dt . (2.1.9)
It isinvariant underthefollowing susytransformations
[Q , x µ ] = ψ µ
,[Q, ψ µ ] = 0 [Q ∗ , x µ ] = 0
,[Q ∗ , ψ µ ] = v µ
[Q ,π µ ] = p ′ µ
,[Q, p ′ µ ] = 0 [Q ∗ , π µ ] = 0
,[Q ∗ , p ′ µ ] = 0 (2.1.10)
andmoreover,theLagrangianis
Q
-exat,L = − i[Q , π µ ³
dx µ dt − v µ ´
]
andthusistheHamiltonian.This isroughly the modelI amgoing to onsider. However, Iwill need some more infor-
mations onthe instanton moduli spae, espeiallyinorder to ndonstraintson thetarget
manifold. Therewill beserveral obstaleswhih have toberesolvedand Iwill listthemup,
wheneverI enounter one. Inthe following andfor onveniene,I willleaveawaytheprime
for
p ′ µ
.2.1.2 The Instanton Moduli Space
Theinstanton equation
dx µ
dt = v µ (x)
givesrise to a sympletormorphismofX
,i.e.L v ω = 0
:φ v : X × Σ → X x 7→ φ v (x, t ) = x(t ) , (2.1.11)
1 Though for the model under consideration CPT is really CT, I will follow the terminology of Frenkel, Losev and
Nekrasov [FLN06]. For a more detailed discussion of CPT breaking, c.f. section 2.2.4.
where
x(t )
is an instanton solution andφ v ( · , t )
determinesa one parameter group int
. Bymeans of this ow equation of
v
one an try to nd a partition ofX
into submanifolds whih isgenerated bythe xedpointsofv
. Thesewill bethedesendingX c
and asendingmanifolds
X c
:X c (c) : = (
x ∈ X : lim
t → (+) − ∞
φ v (x, t ) = x c )
. (2.1.12)
If
x c
isanondegenerateritialpointandφ v
adieormorphism,theyareindeedsubmanifolds [AR67,pg.87f℄and inheritthe tangent spaesdened bytheowlines.ForthefollowingreasonIdemandthatadeompositionof
X
intodesendingandasendingmanifoldsexists. Insetion2.2.4Iwillexplainthatthe statespaeswillbeloalizedaround
thexed pointsof
v
. A deompositionofX
intermsof,say,desendingmanifolds isusefulbeauseone an thenanonially assoiate to eah suh submanifold astate spae
F α
and these overX
. Therefore:❏
Thetarget manifoldX
hasa(Bialyniki-Birula)deompositionX = F
α ∈ A X α = F
α ∈ A X α
withrespettov
.Theinstanton modulispaesaredenedbymeans ofdesendingand asendingmanifolds
M (α,β) : = X α ∪ X β , (2.1.13)
and under further onditions it is possible to alulate thedimension of this moduli spae.
Let
x c
bearitialpoint,Ianhooseloaloordinatessuhthatitisloatedat theorigin.In its neighborhood I an approximate a solution of the instanton equation by a line ele-
ment
y = x c + x
and bymakinga Taylor expansionaround theritialpoint. Thisyields tolowest order
d t x µ − H ν µ (0)x ν = 0
,whith HessianH
evaluated atx c = 0
. Thus, loally aroundthe xed point, the diretions along whih
H
has positive eigenvalues span the tangent spae of the desendingmanifold while the others span thetangent spae of the asendingmanifold. Therefore, at least in a neighborhood of a xed point
x c
,T X c ≃ R dimX − ind(x c )
or≃ C dim C X − 1 2 ind(x c )
while for the asendingmanifold
T X c ≃ R ind(x c )
or≃ C 1 2 ind(x c )
. The general-
izationof this onditionisasfollows:
❏
Let( f , X , λg)
allowfor Morse-Smaletransversality,i.e.∀ x ∈ M (α, β), ∀ α, β : dim T x X α + dim T x X β − dim X = dim ¡
T x X α ∪ T x X β ¢
.
Onean nowalulate
dim R M (α,β) = ind(β) − ind(α) . (2.1.14)
The Morse-Smale ondition yiels a nie desription of the tangent spaes of
X
in terms ofinstanton ow lines. Espeially the dimensions of the instanton moduli spaes are natural
numbersinludingzero,restritedbythedimension ofthetarget manifold,andthereareno
dimensional degeneraies. Sine it is expressedbythe Morse indees, the dimension of the
instanton moduli spae is a topologial invariant. Morse-Smale transversality does further
index.
Thereisanother,physiallyinspiredwaytoalulatethedimensionoftheinstantonmod-
uli spae [H
+
03,se. 10.5.2℄. Consider an instanton solution
x : d t x µ − v µ (x) = 0, x µ ( −∞ ) = x µ α , x µ ( ∞ ) = x β µ
. Again, I will move in the solution spae of this dierential operator toanother solution
y = x + ηz
,whereη > 0
is an innitesimally small number. The urvey
isan instanton solution if the displaement
z
satisesD − z : = ( d t − H (x(t)) ) z = 0, z( ±∞ ) = 0
to the order
η
. For everyt
Imay hoose abasisof eigenvetorsofH(x(t ))
witheigenvaluesκ µ (t )
whih spans the tangent spaeT x(t ) X
. The operatorD −
is diagonal inthis basisandhashomogeneous solutions
z µ (t ) = e µ exp(
Z t
0
κ µ (τ)dτ) , (2.1.15)
where
e µ
diagonalizesD −
att = 0
. These solutions have the orretboundary onditions ifκ µ ( −∞ ) > 0
andκ µ ( ∞ ) < 0
.There are two possible senarios. The rst is that the dimension of the solution spae
equals the dimension of the eigenspae of the Hessian. This is the ase if none of the
eigenvalues
κ µ (t )
hanges its sign from a negative to a positive value when passing fromt = −∞
tot = ∞
. Ifthisissatised,dim R M (α, β) = ind(β) − ind(α) = #{µ : κ µ ( −∞ ) > 0, κ µ ( ∞ ) <
0} = dim ker D −
. Intheseondsenariothereexist eigenvalueswhih hange their signsfrom negative topositvevalue. Theybelongtohomogeneoussolutionsofthedierential operatorD + : = d t + H(x(t ))
. Inthatgeneral ase, thediereneind(β) − ind(α)
an bewritten asdim R M (α,β) = dim ker D − − dim ker D + . (2.1.16)
The operators
D ∓
appear in the equations of motion for the fermionsψ µ
andπ µ
, re-spetively. Under the assumption that the dimension of theinstanton moduli spae equals
dim ker D −
, it further equals the number of linear independent solutions ofD − ψ 0,l = 0, l = 1 . . .d
,d = dim M (α,β)
,whereasπ µ
hasnozeromodes. Thisleadstotheseletionrulethatobservableshave toontaina produt
Q d
l = 1 ψ 0,l
,iftheorrelationfuntion isnot tobezero.Thereason isthat thepath integral isa
δ
distributionon thehomogeneous solutionsofD −
and theinstanton ongurations
x 0
〈 O 〉 = Z
M (α,β)
Y
l = 1...d
ψ 0,l O | M (α,β) . (2.1.17)
AnintegraloverGrassmannvariablesiszeroiftheintegrandisnotavolumeform,andinthe
nextsetionIwillmakelearthat,indeed,thezeromodesof
ψ
have ageometri meaningasdierentials on
X
. Fromthe disussion above Ionlude that they arephysially signifyingthe presene of instantons, and the numberof fermioni insertions ounts thedimension of
their moduli spae.
2
2 In the fermionic bc-system, that I will discuss in the next chapter, it will also be necessary to insert "zero-modes" in
2.2 The Canonical Point of View
The Morse ation (2.1.9) hasan immediate interpretation interms of geometri quantities
of thetarget manifold
X
. Thebestplae to understand this istheanonial formulation of thetheory. Reshueling thetermsin(2.1.9), I anread othelassialHamiltonian inthelarge volume limit 3
H ∞ = v µ (ip µ ) + ψ α ∂ α v µ (iπ µ ) . (2.2.1)
Reonsidering(2.1.10),an immediate hoie howto quantize onsistsinrelatingtheeld-
oordinateswithgeometri quantities inthefollowing way:
bosons: fermions:
x µ x µ ψ µ dx µ
ip µ ∂ µ iπ µ ι µ
(2.2.2)
TheHamiltonian above and thesuperharges
Q
andQ ∗
an nowbe rewritten asQ = d , Q ∗ = ι v , H ∞ = L v = {Q,Q ∗ } , (2.2.3)
and they have a anonial ation on dierential forms on
X
. The geometri data satisfythe usual quantization rules
[p µ , x ν ] = − iδ ν µ , [π µ , ψ ν ] = − iδ ν µ
for the superbraket, and in partiularQ = iψ µ p µ . (2.2.4)
InthefollowingIwillreproduethedeformationsdesribedforthepathintegralansatzfor
theanonial formalismof Morse theory. The ideabehindthis isto seewhat thespetrum
oftheHamiltonianinthelargevolumelimitlookslikeandtoinvestigateifthereremainwell
dened exited states in this limit. I will again start with the ation (2.1.1) before taking
the large volume limit and thetarget manifold
(X ,λg )
, endowed withan inner produt ondierential forms
η,χ ∈ Ω • (X )
〈 η, χ 〉 : = Z
X
( ⋆ η) ¯ ∧ χ . (2.2.5)
Thebar denotesomplexonjugation, ifneessary,and
⋆
theHodgeoperator.4
TheHamil-
tonian orresponding to the ation (2.1.1) with Morse funtion
f
is obtained from thecorrelation functions. These do, however, not represent instantons because they are mappings between isomor- phic representation spaces, cf. section 3.4.1 and section 8.3. On the contrary, instantons relate different vacuum configurations (they are highest weight vectors of different representations).
3 This classical Hamiltonian is not bounded from below. However, in section 2.4, I will derive it from the canonically quantized Hamiltonian with λ 6= 0 by deforming the spectrum in a specific way, cf. [FLN06]. Thereby one obtains states which are not in the closure of Ω •
d (X ) with respect to the L 2 norm, but on which one can define an orthog- onal pairing and whose eigenvalues with respect to the canonically quantized H ∞ are positive semidefinit (when considered perturbatively, c.f. section 2.5). Analogous will be satisfied for the A-model.
4 On volume elements ⋆ dx µ 1 ∧ ··· dx µ k = p | g |
(dim R X − k)! ǫ µ ν 1 ··· µ k
k+1 ··· ν dim X dx ν 1 ∧ ··· dx ν k and ǫ µ 1 ··· µ dim
R X = + 1 for even per-
mutations.
Q = d λ = e − λ f de λ f = d + λ d f ∧ , Q † = d † λ = e λf d † e − λf = 1
λ d † + ι ∇ f ,
(2.2.6)
as
H = ∆ λ = 1
2 {Q,Q † } = 1 2
¡ λ − 1 ∆ + λ k d f k 2 + K f ¢
, (2.2.7)
where,
k df k 2 = ι ∇ f d f
,K f = L ∇ f + L †
∇ f
,L †
∇ f = {d † , df }
and∆ = {d, d † }
. Conjugation†
isdened with respet to the inner produt. Let me emphasize, that up to now CPT is not
broken and the two superharges areindeed onjugate. However, inthelarge volume limit
CPT will be violated and this makes the dierene between the dagger and the star, for
instanefor the superharge in(2.2.3).
2.2.1 On the Cohomology
As I explained in the introdution and in appendix A, the topologial states are in the
ohomologyof thesuperharge
Q
. Underertainonditions onX
,thatIwill onentrateoninthis setion, theohomology of
Q
isisomorphito thekernel of theHamiltonian.The superharges above are obtained by a similarity transformation of
d
andd †
, and IanhenearryovertheresultsonthedeRhamdierentialto themoregeneral situationin
Morse theory, inpartiular that
H d •
λ (X ) ≃ H d • (X )
. IfX
isa real manifold whih is moreoverompat, orientedand without boundary,there existsaunique Hodge deomposition
Ω k
d λ (X ) = d λ Ω k − 1
d λ (X ) ⊕ d † λ Ω k + 1
d λ (X ) ⊕ Ω k
∆ λ (X ) , (2.2.8)
where
Ω k
∆ λ (X)
denotes the harmoni forms onX
withrespet toH = ∆ λ
[Nak03 ℄. If suh a deomposition existsandmoreoveraninnerprodutlike(2.2.5)oneanshowthatH d •
λ (X ) ≃ Ω •
∆ λ (X )
.5 Thus, in order to identify the ohomology of the superharge with the groundstates of the Hamiltonian itwould be sensible to invoke thatwhenever
X
is real, itshouldalso be ompat,orientedand withoutboundary.
If
X
is a ompat Kähler manifold there exist unique, orthogonal Hodge deompositions for theDolbeault derivatives∂ λ
and∂ ¯ λ
. Notiethatinthis ased λ = ∂ λ + ∂ ¯ λ
and similarforthe onjugate. Sine
∆ d
λ = 2 ∆ ∂
λ = 2 ∆ ¯
∂ λ
[Nak03 ℄, one nds thatH ∂ p,q
λ (X ) ≃ Ω p,q
∆ d
λ (X)
and thesame istrue fortheonjugate dierential forms. Therefore:
❏
LetX
beaompatKählermanifoldor,ifreal,ompat,orientedandwithoutbound-ary.
5 Let ω ∈ Ω •
∆ λ (X), then 〈 ω, ∆ λ ω 〉 = 0 = k d λ ω k 2 + k d †
λ ω k 2 and this proves that a harmonic form is closed under d λ and
d † λ . The Hodge decomposition is orthogonal and therefore the harmonic forms are not exact with respect to d λ .
and thekernel ofthe Hamiltionian will survive CPT breakingif
λ < ∞
. Forλ → ∞
this willstill be trueat leastfor
X = CP 1
and Iwill prove this insetion2.4.1.2.2.2 Implementing CPT Breaking and Localization
The transformations I have done on the path integral insetion 2.1.1 an be translated to
the anonial point of view by onsidering orrelation funtions of topologial observables
and states
〈 ω, e (t n − t + )H O n e (t n−1 − t n )H . . .e (t 1 − t 2 )H O 1 e (t − − t 1 )H · χ 〉 = Z
X × X
[ ⋆ ω(x ¯ + )] ∧ χ(x − ) Z
Σ → X : x(t − ) = x − , x(t + ) = x +
O n (t n ) ∧ ··· ∧ O 1 (t 1 )e − S . (2.2.9)
Sine the topologial setor is supposed to be invariant under subtrating the exat term
R x +
x − df = f (x + ) − f (x) + f (x) − f (x − )
fromthe ation,thismusthave aneetontheoperatorsand states. Expetation values of topologial observables, alulated with an Hamiltonian
in whih CPT is manifestly broken by the additional term, must equal the undeformed
expetation values. Therefore, the states and observables in the CPT-broken phase are
subjet to thefollowing transformations ofthe physial ounterparts 6
χ 7→ e λ f χ
⋆ ω ¯ 7→ e − λ f ⋆ ω ¯ O 7→ e λ f O e − λf
and inpartiular
Q 7→ d
Q † 7→ Q λ ∗ = 2ι v + λ − 1 d † H 7→ H λ = L v + 2λ 1 ∆
(2.2.10)
Let me emphasize that all operators transform in the same way and the mappings above
arenot similaritytransformations. Therefore,thenewHamiltonianisnotself-onjugateany
more andI ratherput a
∗
than a†
.One maynowallowthe transformed Hamiltoniannot only to at ontopologial but also
ondynamialstates. Still,fornitevaluesof
λ
,thenewHamiltonianhasthesamespetrum asH
beause the in-states have justgained a phase. In partiular, the isomorphy betweenthe superharge ohomology and the ground states is still valid, though the theory is not
unitary any more and the in- and out-states are no longer onneted by an inner produt
(I will disuss the out states in setion 2.2.4). The Morse theory with broken CPT and
the one determined by(2.2.7) have thesame ohomologieswithrespetto thesuperharge,
sine
H d •
λ ≃ H d •
. Moreover, for niteλ
,H d • ≃ Ω •
∆ λ ≃ Ω • H λ
, suh that
dim Ω •
∆ λ = dim H λ
. Thesedimensionsare atopologial invariantsand thus shouldnot be aetedbytaking