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Multiplication of Eq. (7.86) by −eKeµa gives

eµb =eK(XµN0J−NµJ) ¯PJb. This equation shows that

−eµb∂e¯ aµ=eK(( ¯∂eaµ)NµJ−Xµ( ¯∂eaµ)N0J) ¯PJb =eK( ¯∂PIa)NIJJb. Using the above equation one then finds

ωab (7.70)= −eµb∂e¯ aµ+ ¯eµa∂e¯bµ =eK ( ¯∂PIa)NIJJb−PIaNIJ(∂P¯Jb) . Adding 0(7.86)= δab∂K+eK∂(PIaNIJJb) to the above equation gives

ωabba∂K+eK d(PIaNIJ) ¯PJb−PIa( ¯∂NIJ) ¯PJb

ba∂K+eKd(PIaNIJ) ¯PJb +ieKPIaNIKdFKL(X)NLJJb.

manifolds in the image of the supergravity r-map Kµ¯ν is real, we can choose eaµ to be real (see Eq. (7.62)). Recall how ¯M is realized as a C-quotient of a conical affine special K¨ahler manifold M defined by a holomorphic prepoten-tial F : M → C (see Eq. (7.73) and below). This in particular defines the matrix-valued functions N = (NIJ)I, J=0, ..., n, F = (FIJ)I, J=0, ..., n, etc. on ¯M. Starting from the projective very special K¨ahler manifold ( ¯M, gM¯, JM¯), we now consider the one-loop deformed supergravity c-map. For c∈R, let

N0 :=N(4n+4,0)0 ⊂M¯ ×R2n+4 ⊂R4n+4 (7.87) denote the domain where the one-loop deformed Ferrara-Sabharwal metric gF Sc is positive definite (see Definition 5.5.1). As in Definition 5.5.1, we use standard real coordinates (ρ,φ,˜ ζ˜I, ζI)I=0, ..., non the R2n+4 factor ofN0 and complex coor-dinates (Xµ)µ=1, ..., n on ¯M. Note that on N0, ρ > 0 and ρ+ 2c > 0. We define the following complex-valued one-forms on N0:

β0 :=ieK/2

√ρ+ 2c ρ

n

X

I=0

XIAI, βa :=

rρ+c ρ

n

X

I=0

PIadXI =

rρ+c ρ σa, α0 :=− 1

rρ+ 2c

ρ+c dρ−i ρ+c ρ+ 2c(dφ˜+

n

X

I=0

Idζ˜I−ζ˜II) +cdcK)

! , αa := i

√ρeK/2

n

X

I,J=0

PaINIJAJ (7.88)

(a = 1, . . . , n), where (PIa)I=0,...,n = (P0a, Pµa)µ=1,...,n = (−Pn

ν=1Xνeaν, eaµ)µ=1,...,n and AI = dζ˜I +Pn

J=0FIJ(X)dζJ, I = 0, . . . , n. Here, we trivially extend functions and one-forms from ¯M toN0, using the same notation (i.e. leaving out pullbacks). LetQ= span

R{J10, J20, J30}denote the (trivial) quaternionic structure onN0 obtained from the HK/QK correspondence (see Remarks 5.5.3 and 5.5.4).

Lemma 7.3.1 The coframe

(fαΓ)α=1,2; Γ=1, ...,2n+2 = f1A f1 ˜A f2A f2 ˜A

!

A=0, ..., n

:= βA αA

−¯αA β¯A

!

A=0, ..., n

(7.89)

in(TN0)Cdefines a unitary coframe for the one-loop deformed Ferrara-Sabharwal

metric, i.e. the metric reads gF Sc =

n

X

A=0

Aβ¯AAα¯A), (7.90)

and αA, βA areJ1-holomorphic and fulfill

αA=−J2β¯A (A= 0, . . . , n). (7.91) Proof: Note that τ =−2iρq

ρ+2c

ρ+cα0, whereτ is given by Eq. (5.18). Further-more,

1

4ddcK= i

2∂∂¯K= i

a∧σ¯a = i 2

ρ

ρ+cβa∧β¯a, β0∧β¯0 =eKρ+2cρ2 (XIAI)∧( ¯XJJ) and

αa∧α¯a = 1

ρeKNIKKaPLaNLJAI∧A¯J (7.85)= −1

ρ(NIJ −eKXIJ)AI∧A¯J. Together with Eq. (5.16), this shows that the first fundamental two-form is given by

¯ ω1 = i

2

n

X

A=0

A∧β¯AA∧α¯A). (7.92) Note that

αa∧βa=ieK/2

√ρ+c

ρ PIaKaNKJAJ∧dXI

(7.85)

= ieK/2

√ρ+c

ρ (−AI∧dXI+eKMNM IXJAJ∧dXI)

(7.83)

= +ieK/2

√ρ+c

ρ (dXI∧AI+∂K∧XIAI). (7.93) Together with Eq. (5.17) and the definitions of β0 and α0, this shows that

¯

ω2+i¯ω3 =

n

X

A=0

βA∧αA. (7.94)

The statements of the lemma follow immediately from Eqs. (7.92) and (7.94).

Before we proceed, we state a few more formulas that can be proven using the formulas in Remark 7.2.3 and the definitions of βA, αA. These formulas will be used in later proofs.

Remark 7.3.2 We have

NIJAI∧A¯J =NIJ(FIK −F¯IK)dζK∧dζ˜J =idζJ ∧dζ˜J, (7.95) dXK (7.85)=

(7.83)−XK∂K−eK r ρ

ρ+cNKJJaβa, (7.96)

√i

ρeK/2AJ (7.85)=

r ρ

ρ+ 2cNJ LLβ0−eKPJbαb, (7.97)

√i

ρeK/2L= 2 i

√ρeK/2NLMImAM =−2iNLMRe( i

√ρeK/2AM)

(7.97)

= −2i r ρ

ρ+ 2cRe( ¯XLβ0) + 2ieKNLMRe(PMb αb), (7.98) d( ¯PIaNIJ)NJ LL(7.82)= −P¯IaNIJd(NJ LL)

(7.81)

= −

r ρ ρ+c

β¯a+iP¯IaNIJdFJ L(X) ¯XL, (7.99) eKIaNIJMb NM LFJ KL(X)dXK (7.96)=

(7.81)−e−2K r ρ

ρ+cFeabc(X)βc, (7.100) where fora, b, c= 1, . . . , n,

abc(X) :=

n

X

I, J, K, L, M, N=0

LaNLIMb NM JNcNN KFIJ K(X). (7.101)

Proposition 7.3.3

0 = 1 2

1 + 2c ρ+ 2c

r ρ+c

ρ+ 2c(α0+ ¯α0)−idcK

∧β0+

rρ+ 2c ρ+c

n

X

b=1

αb ∧βb,

a = c

2√

ρ+c√

ρ+ 2c(α0+ ¯α0)∧βa

n

X

b=1

ωab∧βb, dα0 = 1

√ρ+c√ ρ+ 2c

−(ρ+c) + 1 2

cρ ρ+ 2c

α0∧α¯0+ ρ ρ+ 2c

r ρ+c

ρ+ 2cβ0∧β¯0

r ρ+c ρ+ 2c

n

X

b=1

αb∧α¯b− c

√ρ+c√ ρ+ 2c

n

X

b=1

βb∧β¯b, dαa = 1

2(

r ρ+c

ρ+ 2c(α0+ ¯α0)−idcK)∧αa+ ρ

√ρ+c√

ρ+ 2cβ0∧β¯a

n

X

b=1

ωab∧αb−ieK r ρ

ρ+c

n

X

b,c=1

˜habcα¯b∧βc,

where ˜habc =Pn

µ, ν, σ=1eµaeνbeσchµνσ for a, b, c = 1, . . . , n and (ωab)a, b=1, ..., n is the

(pullback toN0 of the) connection one-form of the Levi-Civita connection on M¯ with respect to the given choice of coframe on M¯, i.e. (ωab) is anti-Hermitian and fulfills dσa+Pn

b=1ωab∧σb = 0, a= 1, . . . , n.

Proof: For β0 =ieK/2

ρ+2c

ρ XIAI, we have dβ0 =4

(7.81) (− 1

2ρ 1 + 2c ρ+ 2c

dρ+ 1

2dK)∧β0+ieK/2

√ρ+ 2c

ρ dXI∧AI

= 1

2 1 + 2c ρ+ 2c

r ρ+c

ρ+ 2c(α0+ ¯α0)∧β0+ (∂K− i

2dcK)∧β0 +ieK/2

√ρ+ 2c

ρ dXI∧AI

= 1 2

1 + 2c ρ+ 2c

r ρ+c

ρ+ 2c(α0+ ¯α0)−idcK

∧β0+

rρ+ 2c

ρ+c αb∧βb, since

αa∧βa(7.93)= +ieK/2

√ρ+c

ρ dXI ∧AI+

r ρ+c

ρ+ 2c∂K∧β0. Forβa =q

ρ+c

ρ σa, we have dσa=−ωab∧σb by the definition of (ωab), so dβa=5− c

2ρ 1

ρ+cdρ∧βa−ωab∧βb

= c

2√

ρ+c√

ρ+ 2c(α0+ ¯α0)∧βa−ωab∧βb.

Forα0 =−1 q

ρ+2c ρ+c

dρ−iρ+2cρ+c(dφ˜+ζIdζ˜I−ζ˜II+cdcK)

, we find

0 =6i

−1 ρ +1

2

c

(ρ+c)(ρ+ 2c)

dρ∧Imα0+i 1 2ρ

r ρ+c

ρ+ 2c(2dζI∧dζ˜I+cddcK)

= 2i

√ρ+c√ ρ+ 2c

ρ+c− 1 2

cρ ρ+ 2c

Reα0∧Imα0

| {z }

i 2α0∧¯α0

−1 ρ

r ρ+c ρ+ 2c

ρ αb∧α¯b− ρ2

ρ+ 2cβ0∧β¯0

− c

√ρ+c√

ρ+ 2cβb∧β¯b,

4

∂ρ

ρ+2c

ρ

=1 1 + ρ+2c2c ρ+2c ρ 5

∂ρ

qρ+c

ρ =c ρ+c1 qρ+c

ρ

since

αb∧α¯b = 1

ρeKPKbIbNIJNKLAJ ∧A¯L (7.85)

= −1

ρNJ LAJ∧A¯L+ 1

ρeKXJAJ ∧X¯LL

(7.95)

= −i

ρdζL∧ζ˜L+ ρ

ρ+ 2cβ0∧β¯0 and ddcK= 4ωM¯ = 2iσa∧σ¯a= ρ+c2iρ βa∧β¯a.

Finally, αa = iρeK/2IaNIJAJ fulfills dαa = (− 1

2ρdρ−1

2dK)∧αa+ i

√ρeK/2d( ¯PIaNIJ)∧AJ + i

√ρeK/2IaNIJdFJ L(X)∧dζL

(7.97)

= 1 2

r ρ+c

ρ+ 2c(α0+ ¯α0)∧αa−(i

2dcK+ ¯∂K)∧αa +

r ρ

ρ+ 2cd( ¯PIaNIJ)NJ LL∧β0−eKd( ¯PIaNIJ)PJb∧αb + i

√ρeK/2IaNIJdFJ L(X)∧dζL

(7.99)

=

(7.98)

1 2

r ρ+c

ρ+ 2c(α0+ ¯α0)∧αa−(i

2dcK+ ¯∂K)∧αa

(((((((((((((((((((

+i r ρ

ρ+ 2c

IaNIJdFJ L(X) ¯XL∧β0− ρ

√ρ+c√ ρ+ 2c

β¯a∧β0

−eKd( ¯PIaNIJ)PJb ∧αb

((((((((((((((((((((((

−2i r ρ

ρ+ 2c

IaNIJdFJ L(X)∧Re( ¯XLβ0) + 2ieKIaNIJdFJ L(X)NLM ∧Re(PMb αb)

(7.81),(7.79)

=

(7.100)

1 2(

r ρ+c

ρ+ 2c(α0+ ¯α0)−idcK)∧αa+ ρ

√ρ+c√

ρ+ 2cβ0∧β¯a

−ωab∧αb+ie−2K r ρ

ρ+cFeabc(X) ¯αb∧βc. Finally, note that

abc(X) = −e3K˜habc(ImX). (7.102)

6

∂ρ

−i2|ρ|σ1 q ρ+c

|ρ+2c|

=−i2|ρ|σ1 q ρ+c

|ρ+2c|

ρ1+12(ρ+c)(ρ+2c)c

Recall that ¯θ1 = −12q

ρ+2c

ρ+c Imα014dcK and ¯θ2+iθ¯3 =q

ρ+c

ρ+2cβ0 (see Remark 5.5.3). The H-part of the Levi-Civita connection is given by (see Eq. (7.48))

p= p11 p12 p21 p22

!

=

14(−idcK+q

ρ+2c

ρ+c ( ¯α0−α0)) −q

ρ+c ρ+2cβ0 qρ+c

ρ+2cβ¯0 14(−idcK+q

ρ+2c

ρ+c ( ¯α0−α0))

 .

Corollary 7.3.4 The E-part of the Levi-Civita connection with respect to the frame (EΓ) for the one-loop deformed q-map is given by (ΘΓ) = qAB tA˜

B

−t¯A˜BA˜˜

B

!

with (qAB) =q,

q=

i

4dcK+14ρ+c1ρ+2c

3ρ+ρ+2c4c2

( ¯α0−α0) −q

ρ+c ρ+2cαb qρ+c

ρ+2cα¯a ωab+14(−idcK+ ρ+cρρ+2c( ¯α0−α0))δab

and

t= (tAB˜) =

2c ρ+2c

qρ+c

ρ+2cβ0 ρ+ccρ+2cβb

c ρ+c

ρ+2cβa ieKq ρ

ρ+c˜habcαc

 .

Proof: q is anti-Hermitian and t is symmetric. A straightforward calculation shows that the equations given in Proposition 7.3.3 agree with equations (7.50) and (7.51), whenq and t are given as above.

From now on, we restrict ourselves to the undeformed q-map, i.e. we set c= 0.

Proposition 7.3.5 The E-part of the curvature two-form with respect to the frame (EΓ) is given for any quaternionic K¨ahler manifold in the image of the

q-map by (REΓ) = rAB sA˜

B

−¯sA˜BA˜˜

B

!

with (rAB) = r,

r =

 1

2 α0∧α¯0−β0∧β¯0 +

n

X

C=0

αC ∧α¯C−βC ∧β¯C αb∧α¯0+ ¯βb∧β0+ieK˜hbcdα¯c∧βd

α0 ∧α¯a+ ¯β0∧βa +ieK˜hacdαc∧β¯d

1 2δab

n

X

C=0

C ∧α¯C −βC∧β¯C)

−(βa∧β¯b+ ¯αa∧αb)

−e2Kadc˜hcebd∧α¯e+ ¯βd∧βe)

and (sA˜

B) = s,

s = 0 0

0 ieK˜habc0∧β¯c+ ¯α0∧αc) +e2K˜habf˜hf deα¯d∧βe−2Sabcdαc∧β¯d

! ,

where Sabcd :=−1

2e2K

(˜hbcf˜hf ad−4˜hbc˜had) + (˜hacf˜hf bd−4˜hac˜hbd) + (˜habf˜hf cd−4˜hab˜hcd) + 4˜habcd+ 4˜hb˜hcda+ 4˜hc˜hdab+ 4˜hd˜habc

.

Proof: First, we calculate dq:

dq00 = i

4ddcK+3

4(d¯α0−dα0)(d¯α

0=−dα0)

= −1

2∂∂¯K− 3 2dα0

=−1

c∧β¯c+3

2(α0∧α¯0−β0∧β¯0c∧α¯c),

dq0b =−dqb0 =−dαb

=−1

2(α0+ ¯α0 −idcK)∧αb−β0∧β¯b+ ¯ωbc∧αc+ieK˜habcα¯a∧βc,

dqab =dωab +1

ab(∂∂¯K−dα0)

=dωab +1

abc∧β¯c0∧α¯0−β0∧β¯0c∧α¯c).

Then with

(qAC∧qCB) =

−αc∧α¯c12(idcK+ ¯α0 −α0)∧αb−ω¯bc∧αc

12(idcK+ ¯α0−α0)∧α¯aac∧α¯c ωac∧ωcb−α¯a∧αb

!

and

(tAC ∧¯tCB) = 0 0

0 e2K˜hadc˜hcebαd∧α¯e

! , we obtain

r(7.56)= dq+q∧q−t∧¯t

=

 1

2(αc∧α¯c−βc∧β¯c) +3

2(α0∧α¯0−β0∧β¯0)

αb∧α¯0+ ¯βb∧β0+ieK˜hbcdα¯c∧βd

α0∧α¯a+ ¯β0∧βa +ieK˜hacdαc∧β¯d

abac∧ωcb −α¯a∧αb−e2K˜hadccebαd∧α¯e +1

abc∧β¯cc∧α¯c0∧α¯0−β0∧β¯0)

 .

This can be brought into the form stated above using (see Eq. (7.72)) dωabac∧ωcb =−δabβc∧β¯c−βa∧β¯b+e2K˜hadccebβe∧β¯d.

Since eaµ is real, we have eaµdeµb = ¯eaµd¯eµb (7.70)= ω¯ab + ¯mab, where mab :=eaµ∂eµb+ ¯ebµ∂¯eµa. Using d(˜habc) = ˜hdbcedµdeµa+ ˜hadcedµdeµb+ ˜habdedµdeµc, we calculate

dtad=ieK˜habc(x) dK∧αc+1

2(α0+ ¯α0−idcK)∧αc0∧β¯c

−ω¯cd∧αd−ieK˜hcde(x) ¯αd∧βe +ieK ˜hdbc(¯ωda+ ¯mda) + ˜hadc(¯ωdb+ ¯mdb) + ˜habd(¯ωdc+ ¯mdc)

∧αc.

With

qAC ∧tCB ω

a c=−¯ωca

= 0 0

0 −ieK˜hcbeω¯ca∧αe+4ieKabe(−idcK+ ¯α0−α0)∧αe

!

and

tAC∧q¯CB = 0 0

0 ieK˜haceαe∧ω¯cb+4ieKabe(−idcK+ ¯α0−α0)∧αe

! , we obtain

s(7.57)= dt+q∧t+t∧q¯= 0 0 0 sab

! , where

sab =ieK˜habc

(dK+ ¯α0−idcK)∧αc0∧β¯c−ieK˜hcdeα¯d∧βe +ieK(˜hdbcda+ ˜hadcdb+ ˜habddc)∧αc

= 8e2Kabc˜hdβ¯d∧αc+ieKabc0∧β¯c+ ¯α0∧αc) +e2K˜habccdeα¯d∧βe +ieK(˜hdbcda+ ˜hadcdb+ ˜habddc)∧αc.

In the last equality, we used

dK−idcK= 2 ¯∂K=− i

h(x)hµ(x)eµdβ¯d=−8ieK˜hdβ¯d. Now, using

mab =−eaρeµbeσcΓρµσβc and (see (7.64) and (6.4))

Γρσµ =− i 2h

hhρκhκµσ −hσδµρ−hµδρσ+ 1 2xρhµσ

, eνaeλa =K¯νλ =−4h(x)hνλ(x) + 2xνxλ, we find

˜hdbcda =ieK(˜hbcf˜hf da−4˜hbc˜hda+ 4˜habcd+ 4˜hd˜habc) ¯βd. Hence,

sab =ieKabc0∧β¯c+ ¯α0∧αc) +e2K˜habff deα¯d∧βe

−e2K

(˜hbcf˜hf ad−4˜hbc˜had) + (˜hacf˜hf bd−4˜hac˜hbd) + (˜habf˜hf cd−4˜hab˜hcd)

β¯d∧αc

−4e2K(˜habcd+ ˜hb˜hcda+ ˜hcdab+ ˜hd˜habc) ¯βd∧αc.

Remark 7.3.6 Note that the vanishing of the symmetric quartic tensor field Sabcdσa⊗σb⊗σc⊗σd

=−1 2

1 43h2

3hτ(µνKτ τ0hσρ)τ0. . .

. . .−12h(µνhσρ)+ 16hhνσρ)

!

dXµ⊗dXν ⊗dXσ⊗dXρ

=−1 2

1 43h2

−12hτ(µνhτ τ0hσρ)τ0. . . . . .−6h(µνhσρ)+ 16hhνσρ)

!

dXµ⊗dXν ⊗dXσ⊗dXρ

on the projective special K¨ahler manifold ( ¯M, gM¯, JM¯) is a necessary and suffi-cient condition for ( ¯M, gM¯) to be symmetric [CV].

In the following theorem, we use the notation from Section 7.1.

Theorem 7.3.7 The Sp(E)-curvature of manifolds in the image of the q-map can be written as

ΓΓ0 =−1

2αβCΓ0Γ00fαΓ∧fβΓ00+CΓΓ0Γ0Γ0Γ00Γ000αβfαΓ00∧fβΓ000, (7.103) where the non-vanishing components of the symmetric quartic tensor field Ω are given by

00˜0 = 1

2, Ω0b˜0 ˜d= 1

bd, Ωab˜cd˜= 1

4(δacδbdadδbc)−1

2e2K˜habf˜hf cd, Ω˜0bcd = Ωcd˜=−i

2eK˜hbcd, Ωabcd = Ω˜a˜cd˜=Sabcd (and symmetrization thereof ).

Proof: First, note that (αβCΓ0Γ00fΓα∧fΓ00β)Γ=A,A˜

Γ0=B,B˜ = βA∧β¯B+ ¯αA∧αB βA∧α¯B˜−α¯A∧βB˜ αA˜∧β¯B−β¯A˜∧αB αA˜∧α¯B˜ + ¯βA˜∧βB˜

! .

Define

UΓΓ0 :=αβfΓα∧fΓ0β = −βA∧α¯B+ ¯αA∧βB βA∧β¯B˜ + ¯αA∧αB˜

−αA˜∧α¯B−β¯A˜∧βB αA˜∧β¯B˜ −β¯A˜∧αB˜

!

and

Γ0Γ0 :=CΓ0Γ( ˜RΓΓ0 +1

2αβCΓ0Γ00fΓα∧fΓ00β).

Then

AB˜ =− rAB+ 1

2(βA∧β¯B+ ¯αA∧αB)

=

 1

2(β0∧β¯0+ ¯α0∧α0) +1

2(βC ∧β¯C+ ¯αC ∧αC)

1

20∧β¯b + ¯α0∧αb) +ieK˜hbdeβe∧α¯d

1

2(βa∧β¯0+ ¯αa∧α0)

−ieKadeαd∧β¯e

1

abC ∧β¯C + ¯αC∧αC) +1

2(βa∧β¯b+ ¯αa∧αb)

+e2Kadc˜hcebd∧α¯e+ ¯βd∧βe)

=

1

4(U0+U˜00+UCC˜ +UCC˜ ) 14(Ub+U˜b0)− 2ieKbdeUde

1

4(Ua˜0+U˜0a)− 2ieK˜hadeU˜e 1

ab(UCC˜ +UCC˜ ) + 1

4(Ua˜b+U˜ba)

− e2K 2

˜hadf˜hf eb(Ue+Ude˜)

 ,

A˜B˜ =− sAB+1

2(βA∧α¯B−α¯A∧βB)

=

−β0∧α¯0120∧α¯b−α¯0∧βb)

12a∧α¯0 −α¯a∧β0) − 1

2(βa∧α¯b−α¯a∧βb) +e2K˜habf˜hf deβd∧α¯e

−ieK˜habc0∧β¯c+ ¯α0∧αc) + 2Sabcdαc∧β¯d

=

1

2U00 14(U0b+Ub0)

1

4(Ua0 +U0a) 1

4(Uab+Uba)−e2K 2

˜habf˜hf deUde

− i 2

abc(Uc+U˜c0) +SabcdU˜cd˜

 ,

and ˚RAB = ˚RA˜B˜, ˚RAB˜ =−R˚AB˜ .

Eq. (7.58) is equivalent to ˚RΓΓ0 = ΩΓΓ0Γ00Γ000UΓ00Γ000. Now ˚R˜00 = Ω˜00Γ00Γ000UΓ00Γ000

implies Ω˜00CD = Ω˜00 ˜CD˜ = 0, Ω˜000 ˜d= Ω˜00c˜0 = 0 and Ω˜000˜0 = 1

2, Ω˜00cd˜= 1 4δcd.

˜a0 = Ωa0Γ˜ 00Γ000UΓ00Γ000 implies Ωa0CD˜ = 0, Ω˜a00 ˜d= 0, Ωa0c˜ d˜= 0 and Ω˜a0˜cd˜=−i

2eKacd.

˜ab = ΩabΓ˜ 00Γ000UΓ00Γ000 implies Ω˜abC˜D˜ = 0, Ω˜abcd = 0, Ω˜ab˜0d = 0 and Ω˜ab˜cd = 1

4(δabδcdbcδad)−e2K 2

˜hacf˜hf db. R˚˜0b = Ω˜0bΓ00Γ000UΓ00Γ000 implies Ω˜0b˜0 = 0, Ω˜0b˜0d= 0 and

˜0bcd =−i

2eKbcd.

It remains to determine the components of the form ΩABCD and ΩA˜B˜C˜D˜: R˚A˜B˜ = ΩA˜˜ 00Γ000UΓ00Γ000 implies Ω˜0 ˜BC˜D˜ = 0 and

˜a˜cd˜=Sabcd.

UsingUAB =UA˜B˜ andUAB˜ =−UAB˜ , we find that ˚RAB = ˚RA˜B˜ = ΩABΓ00Γ000UΓ00Γ000 implies Ω0BCD = 0 and

abcd =Sabcd.

7.4 Example: A series of inhomogeneous com-plete quaternionic K¨ ahler manifolds

In this section, we show that the members of a certain series of complete quater-nionic K¨ahler manifolds constructed from the q-map are not locally homoge-neous. This is done by calculating the pointwise norm of the Riemann tensor and showing that it is a non-constant function on the quaternionic K¨ahler mani-fold. We leave out the details of the calculation and just show some intermediate steps and the final result. Note that some simplifications of formulas were done using computer algebra software.

We will again leave out summation symbols and employ Einstein’s summation convention.

Forn ∈N, we consider the following series of projective special real manifolds:

H={h= 1, x > 0} ⊂Rn, h:=x(x2

n−1

X

i=1

(yi)2). (7.104) The projective special real manifold (H, gH) is a closed subset of Rn and thus complete according to Theorem 6.2.8 (which was proven in [CNS]). Due to Theorems 6.2.6 and 6.3.3 (which were proven in [CHM]), the corresponding projective special K¨ahler manifold obtained from the supergravity r-map and the quaternionic K¨ahler manifold obtained from the q-map are complete as well.

The scalar curvature of the corresponding projective special K¨ahler manifold ¯M in the image of the supergravity r-map can be calculated to be (see Theorem 3 in7 [CDL] for the general formula)

scalM¯ =−2n2+n−2hhαβγhαα0hββ0hγγ0hα0β0γ0

=−2n(n+ 1) + 1

32h2hαβγKαα0Kββ0Kγγ0hα0β0γ0

=−n·(2n−1) + 3h· n−2

h−4x3 + 36x3h2

(h−4x3)3. (7.105) We find the following expression for the squared pointwise norm of the quartic tensor field Bµνσρ :=hµνκKκκ0hκ0ρσ on ¯M:

BµνσρKµµ0Kνν0Kσσ0Kρρ0Bµ0ν0σ0ρ0 = 4096h4 (h−4x3)6 ·

h6(n−1)(n+ 3)

−4h5(n+ 3)(5n−7)x3 + 4h4(n(41n+ 98)−159)x6

−64h3(n(11n+ 43)−75)x9+ 128h2(n(13n+ 73)−78)x12

−2048h(n(n+ 7)−3)x15+ 1024n(8 +n)x18

. (7.106)

The squared pointwise norm of the Riemann tensor of the projective special K¨ahler manifold is (see Theorem 3 in [CDL] for the general formula for the

7Note that compared to [CDL] we scaled the projective special K¨ahler metric gM¯ by a factor of 12, which leads to a scaling of the scalar curvaturescalM¯ by a factor of 2.

Riemann tensor)

kRM¯k2 = 16Rµνσ¯ ρ¯Kµµ0Kνν0Kσσ0Kρρ0Rµ0¯ν0¯σ0ρ0

=−32scalM¯ −32n(n+ 1) + 1

44h4BρσµνKρρ0Kσσ0Kµµ0Kνν0Bρ0σ0µ0ν0

= 16

(h−4x3)6

h6(n(3n−8) + 9)−4h5(n(17n−46) + 57)x3 + 4h4(n(161n−382) + 537)x6−64h3(n(51n−97) + 99)x9 + 128h2(n(73n−107) + 78)x12−2048h(n(7n−8) + 3)x15 + 1024n(9n−8)x18

. (7.107)

For the squared pointwise norm of the tensor field Sµνσρ=−1

2e2K

(˜hbcf˜hf ad−4˜hbc˜had) + (˜hacf˜hf bd−4˜hac˜hbd) + (˜habf˜hf cd−4˜hab˜hcd)

+ 4˜ha˜hbcd+ 4˜hb˜hcda+ 4˜hc˜hdab+ 4˜hd˜habc

on ¯M (see the definition ofS in Proposition 7.3.5), we find:

SµνσρKµµ0Kνν0Kσσ0Kρρ0Sµ0ν0σ0ρ0 (7.108)

= 3x6 (h−4x3)6

h4(n(n+ 16) + 207)−16h3(n−2)(n+ 9)x3 + 96h2 n2+n−6

x6−256h(n−2)nx9+ 256(n−2)nx12 . The squared pointwise norm of the quaternionic Weyl tensor is

1

64kWk2 = ΩΓΓ0Γ00Γ000CΓ∆CΓ00CΓ0000CΓ000000∆∆000000

= 2ΩABCDA˜B˜C˜D˜ −8ΩABCD˜A˜B˜CD˜ + 6ΩABC˜D˜A˜BCD˜

= 2Ωabcd˜a˜cd˜−8Ωabc˜0a˜˜c0+ 6(Ω00˜0)2+ 24Ω0b˜0 ˜d˜b0d+ 6Ωab˜cd˜˜a˜bcd

= 2SabcdSabcd+ 2n(n+ 1) +scalM¯ + 3

2(n+ 1) + 6( 1

43kRM¯k2+ 1

4scalM¯ +n2+n 8 )

= 2SabcdSabcd+1

4(11n+ 6)(n+ 1) + 3

32kRM¯k2+5 2scalM¯

= 3

2 (h−4x3)6

h6n(n+ 1)−4h5(n+ 1)(5n−2)x3+ 8h4(n(21n+ 37) + 112)x6

−256h3(n(3n+ 10)−11)x9+ 256h2(n(8n+ 33)−20)x12

−1024h(n(3n+ 11) + 2)x15+ 2048(n+ 1)(n+ 2)x18 + 3n

4 (n+ 1). (7.109)

By evaluating the above function in different points, one can check that it is non-constant for n >1. This gives the following proposition:

Proposition 7.4.1 For n >1, the series of manifolds obtained from the com-plete projective special real manifolds in Eq. (7.104) via the q-map consists of complete quaternionic K¨ahler manifolds that are not locally homogeneous.

Remark 7.4.2 The curvature tensor of the quaternionic K¨ahler manifolds discussed above splits as R = νRHPn+1 + W. Note that in our conventions for quaternionic K¨ahler manifolds obtained via the supergravity c-map from an 2n-dimensional projective special K¨ahler manifold manifold, the reduced scalar curvature is ν =−2. The squared pointwise norm of RHPn+1 is

kRHPn+1k2 = 20n2+ 44n+ 24 = 20(n+ 1)2+ 4(n+ 1). (7.110) Using computer algebra software, we have calculated the squared pointwise norm kRk2 of the Riemann tensor for n = 2 and n = 3 and have checked that kRk2 −4kRHPn+1k2 agrees with the squared pointwise norm of the Weyl ten-sor in Eq. (7.109).

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I am particularly indebted to my supervisor Vicente Cort´es for introducing me to the c-map and to quaternionic K¨ahler geometry, and for his guidance and support during my time in Hamburg. Thanks a lot!

Thanks also go to Oliver Goertsches and Jan Louis for giving advice on the mathematical, respectively physical part of my work as part of my supervisory committee.

I would like to thank my coauthors Thomas Mohaupt, Dmitri Alekseevsky and David Lindemann for inspirational collaborations and enjoyable discussions.

I also want to thank my fellow PhD students Benedict Meinke, Marco Freibert, Lana Casselmann and Peter-Simon Dieterich in the differential geometry group who, apart from enriching my private life, took part in invaluable discussions and answered even my most stupid questions.

For further work-related discussions, I would like to thank Andrew Swann, An-driy Haydys, Sergei Alexandrov, Stefan Vandoren and Uwe Semmelmann.

I would also like to thank Andriy Haydys and Stefan Vandoren for taking the time and effort to grade my PhD thesis.

Special thanks go to Owen Vaughan. Apart from inviting me to parties, and from playing and watching football with me, he invited me to the University of Liverpool, and, during our time in Hamburg, he explained to me all the formulas and tricks that can be found in the physics literature on special geometry.

Many thanks to Giovanni Bazzoni, in particular for inviting me to Bielefeld University on several occasions.

This work was made possible by the financial support and stimulating atmo-sphere of the RTG 1670 “Mathematics inspired by String Theory and Quantum Field Theory”. I would like to thank all present and former members of the RTG 1670 and all colleagues at the Department of Mathematics in Hamburg for this fruitful and friendly environment. Particular thanks in this regard go to my office mate Sebastian Novak.

Thanks a lot to my family, to Paloma IV and to my friends from Schwerte for supporting me and giving my life meaning.

My deepest gratitude belongs to Charlotte for being in my life and for marrying me.

D.V. Alekseevsky, V. Cort´es, M. Dyckmanns and T. Mohaupt, Quaternionic K¨ahler metrics associated with special K¨ahler manifolds, J. Geom. Phys.92 (2015), 271–287.

This collaboration was part of my doctoral project. The formulation of the HK/QK correspondence in Section 4.1 is (as opposed to its proof) taken from this publication. The same is true for the account of the Swann bundle construction in Section 3.6. The application of the HK/QK correspondence to the c-map in Sections 5.1–5.4 is part of this publication. The results on the K¨ahler/K¨ahler correspondence from this publication did not enter this doctoral thesis.

V. Cort´es, M. Dyckmanns and D. Lindemann, Classification of complete projective special real surfaces, Proc. London Math. Soc. 109 (2014), no. 2, 423–445.

My contribution to this collaboration is mainly based on my M.Sc. thesis written in Hamburg under the supervision of Vicente Cort´es. In this doctoral thesis, the classification of projective special real surfaces is only mentioned in a short remark in Chapter 6. Chapter 7 makes some use of the curvature results for projective very special K¨ahler manifolds from this publication.

M. Dyckmanns,

A twistor sphere of generalized K¨ahler potentials on hyperk¨ahler manifolds, arXiv:1111.3893 (hep-th).

This preprint contains the results of my M.A. thesis written in Stony Brook under the supervision of Martin Roˇcek and is essentially unrelated to this doctoral thesis.