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ASYMPTOTIC FREEDOM IN HORAVA-LIFSHITZ GRAVITY
GIULIO D’ODORICO
ERG 2014 Conference, Lefkada, Greece
Based on: G.D., F. Saueressig, M. Schutten, arXiv:1406.4366 and G.D., Frank Saueressig, in preparation
OVERVIEW
Giulio D’Odorico ERG 2014 - 23 September 2014
Giulio D’Odorico ERG 2014 - 23 September 2014
Theory Space: Quantum Einstein GravitySymmetry: Diffeomorphisms
FP Structure of Quantum Gravity
Giulio D’Odorico ERG 2014 - 23 September 2014
Theory Space: Quantum Einstein GravitySymmetry: Diffeomorphisms
NGFPβ
FP Structure of Quantum Gravity
GFP
• Critical properties “easy” to determine with perturbative methods
Giulio D’Odorico ERG 2014 - 23 September 2014
Theory Space: Quantum Einstein GravitySymmetry: Diffeomorphisms
NGFPβ
FP Structure of Quantum Gravity
GFP
• Critical properties “easy” to determine with perturbative methods
• Unfortunately gravity is perturbatively nonrenormalizable
Giulio D’Odorico ERG 2014 - 23 September 2014
Theory Space: Quantum Einstein GravitySymmetry: Diffeomorphisms
NGFPβ
FP Structure of Quantum Gravity
GFP
[GN ] = −2
Horava-Lifshitz Gravity in a nutshell
Giulio D’Odorico ERG 2014 - 23 September 2014
• Anisotropic field theories: change dispersion relation
• Decreases degree of divergence in loop integrals
Horava-Lifshitz Gravity in a nutshell
Giulio D’Odorico ERG 2014 - 23 September 2014
t → b t,
x → b1/z xS =
� �φ̇2 − φ∆zφ+
N�
n=1
gnφn
�dt ddx
• Anisotropic field theories: change dispersion relation
• Decreases degree of divergence in loop integrals
• Gravity: Folation-Preserving Diffeomorphisms
• Natural formulation in ADM variables:
Horava-Lifshitz Gravity in a nutshell
Giulio D’Odorico ERG 2014 - 23 September 2014
t → b t,
x → b1/z xS =
� �φ̇2 − φ∆zφ+
N�
n=1
gnφn
�dt ddx
ds2 = N2dt2 + σij
�dxi +N idt
� �dxj +N jdt
�
t → f(t)
x → ζ(t,x)
• Anisotropic field theories: change dispersion relation
• Decreases degree of divergence in loop integrals
• Gravity: Folation-Preserving Diffeomorphisms
• Natural formulation in ADM variables:
Horava-Lifshitz Gravity in a nutshell
Giulio D’Odorico ERG 2014 - 23 September 2014
t → b t,
x → b1/z xS =
� �φ̇2 − φ∆zφ+
N�
n=1
gnφn
�dt ddx
ds2 = N2dt2 + σij
�dxi +N idt
� �dxj +N jdt
�
t → f(t)
x → ζ(t,x)
N(t, x) = N(t) Projectable HL Gravity
Giulio D’Odorico ERG 2014 - 23 September 2014
Theory Space: Horava-LifshitzSymmetry: Foliation Preserving Diffs
NGFP
Subspace: Quantum Einstein GravitySymmetry: Diffs
GFP
aGFPβ
FP Structure of Quantum Gravity
• Is the theory asymptotically free?
• Does it reproduce the correct phenomenology?
• Does ti resolve previous issues?
Questions
Giulio D’Odorico ERG 2014 - 23 September 2014
• Is the theory asymptotically free?
Questions
Giulio D’Odorico ERG 2014 - 23 September 2014
MATTER-INDUCED FLOWS IN
PROJECTABLE HL GRAVITY
Giulio D’Odorico ERG 2014 - 23 September 2014
Ansatz
Giulio D’Odorico ERG 2014 - 23 September 2014
• Projectable Horava-Lifshitz action plus anisotropic scalar
Ansatz
Giulio D’Odorico ERG 2014 - 23 September 2014
Γk[N,Ni,σ,φ] = ΓHL
k [N,Ni,σ] + SLS[N,Ni,σ,φ]
• Projectable Horava-Lifshitz action plus anisotropic scalar
Ansatz
Giulio D’Odorico ERG 2014 - 23 September 2014
Γk[N,Ni,σ,φ] = ΓHL
k [N,Ni,σ] + SLS[N,Ni,σ,φ]
ΓHL
k = 1
16πGk
�dtddxN
√σ�KijK
ij − λkK2 + Vk
�
• Projectable Horava-Lifshitz action plus anisotropic scalar
• Potential V is a function of the intrinsic curvatures:
Ansatz
Giulio D’Odorico ERG 2014 - 23 September 2014
Γk[N,Ni,σ,φ] = ΓHL
k [N,Ni,σ] + SLS[N,Ni,σ,φ]
ΓHL
k = 1
16πGk
�dtddxN
√σ�KijK
ij − λkK2 + Vk
�
V (d=2)k = g0 + g1 R+ g2 R
2
V (d=3)k = g0 + g1R+ g2R
2 + g3RijRij − g4R∆xR
− g5Rij∆xRij + g6R
3 + g7RRijRij + g8R
ijR
jkR
ki
• Projectable Horava-Lifshitz action plus anisotropic scalar
• Minimally coupled anisotropic scalars with covariant derivatives
Ansatz
Giulio D’Odorico ERG 2014 - 23 September 2014
SLS ≡ 12
�dtddxN
√σφ [∆t + (∆x)
z]φ
∆t ≡ − 1N
√σ∂t N
−1√σ ∆x ≡ −σij∇i∇j
Γk[N,Ni,σ,φ] = ΓHL
k [N,Ni,σ] + SLS[N,Ni,σ,φ]
• Projectable Horava-Lifshitz action plus anisotropic scalar
• Minimally coupled anisotropic scalars with covariant derivatives
• We will consider the beta functions for large-n (with n the number of scalars)
Ansatz
Giulio D’Odorico ERG 2014 - 23 September 2014
SLS ≡ 12
�dtddxN
√σφ [∆t + (∆x)
z]φ
∆t ≡ − 1N
√σ∂t N
−1√σ ∆x ≡ −σij∇i∇j
Γk[N,Ni,σ,φ] = ΓHL
k [N,Ni,σ] + SLS[N,Ni,σ,φ]
ANISOTROPIC HEAT-KERNELS
Giulio D’Odorico ERG 2014 - 23 September 2014
HK for Anisotropic Operators
Giulio D’Odorico ERG 2014 - 23 September 2014
• Need the Heat Kernel for anisotropic operator:
• It is possible to reduce the problem to an Off-Diagonal Heat Kernel computation.
HK for Anisotropic Operators
Giulio D’Odorico ERG 2014 - 23 September 2014
D2 ≡ ∆t + (∆x)z∂tΓk = Tr O
�D
2�
[ Benedetti, Groh, Machado, Saueressig JHEP 06 (2011) 079 ][ Anselmi, Benini JHEP 10 (2007) 099 ]
• Need the Heat Kernel for anisotropic operator:
• It is possible to reduce the problem to an Off-Diagonal Heat Kernel computation.
• For a scalar we find:
HK for Anisotropic Operators
Giulio D’Odorico ERG 2014 - 23 September 2014
D2 ≡ ∆t + (∆x)z
Tr e−sD2
� (4π)−(d+1)/2 s−(1+d/z)/2
�dtddxN
√σ×
�s
6
�e1 K
2 + e2 KijKij�+
�
n≥0
sn/z bn a2n
�
∂tΓk = Tr O�D
2�
N = 1, N i = 0
[ Benedetti, Groh, Machado, Saueressig JHEP 06 (2011) 079 ][ Anselmi, Benini JHEP 10 (2007) 099 ]
• The e coefficients are:
•The b coefficients come in two classes:
Anisotropic HK: Results
Giulio D’Odorico ERG 2014 - 23 September 2014
e1 =d− z + 3
d+ 2
Γ( d2z )
zΓ(d2 ), e2 = −d+ 2z
d+ 2
Γ( d2z )
zΓ(d2 )
0 ≤ n ≤ �d/2�bn =
Γ�d−2n2z + 1
�
Γ�d−2n
2 + 1�
n > �d/2�bn(d, z) ≡
(−1)k
Γ(d/2− n+ k)
� ∞
0dxxd/2−n+k−1 (∂x)
k e−xz
k = n+ 1− �d/2�
Giulio D’Odorico ERG 2014 - 23 September 2014
d = 2 d = 3
z = 1 z = 2 z = 3 z = 1 z = 2 z = 3 z = 4
b0 1√π2 Γ( 43 ) 1 4
3√πΓ( 74 )
23
43√πΓ( 118 )
b1 1 1 1 1 2√πΓ( 54 )
2√πΓ( 76 )
2√πΓ( 98 )
b2 1 0 0 1 1√πΓ( 34 )
1√πΓ( 56 )
1√πΓ( 78 )
b3 1 −2 0 1 − 2√πΓ( 54 ) − 1
2 − 12√πΓ( 58 )
b4 1 0 6 1 − 4√πΓ( 74 )
92√πΓ( 76 )
2√πΓ( 118 )
• z=1 reproduces standard covariant results
Giulio D’Odorico ERG 2014 - 23 September 2014
d = 2 d = 3
z = 1 z = 2 z = 3 z = 1 z = 2 z = 3 z = 4
b0 1√π2 Γ( 43 ) 1 4
3√πΓ( 74 )
23
43√πΓ( 118 )
b1 1 1 1 1 2√πΓ( 54 )
2√πΓ( 76 )
2√πΓ( 98 )
b2 1 0 0 1 1√πΓ( 34 )
1√πΓ( 56 )
1√πΓ( 78 )
b3 1 −2 0 1 − 2√πΓ( 54 ) − 1
2 − 12√πΓ( 58 )
b4 1 0 6 1 − 4√πΓ( 74 )
92√πΓ( 76 )
2√πΓ( 118 )
• z=1 reproduces standard covariant results
• z=d=2 reproduces Baggio, de Boer, Holsheimer, arXiv:1112.6416
Giulio D’Odorico ERG 2014 - 23 September 2014
d = 2 d = 3
z = 1 z = 2 z = 3 z = 1 z = 2 z = 3 z = 4
b0 1√π2 Γ( 43 ) 1 4
3√πΓ( 74 )
23
43√πΓ( 118 )
b1 1 1 1 1 2√πΓ( 54 )
2√πΓ( 76 )
2√πΓ( 98 )
b2 1 0 0 1 1√πΓ( 34 )
1√πΓ( 56 )
1√πΓ( 78 )
b3 1 −2 0 1 − 2√πΓ( 54 ) − 1
2 − 12√πΓ( 58 )
b4 1 0 6 1 − 4√πΓ( 74 )
92√πΓ( 76 )
2√πΓ( 118 )
RESULTS
Giulio D’Odorico ERG 2014 - 23 September 2014
• Defining
• The beta functions for the dimensionless couplings read
Beta Functions
Giulio D’Odorico ERG 2014 - 23 September 2014
gk ≡ Gk k2η , η ≡ d
2z − 12 φn ≡ 1
Γ(n)
� 1
0dx xn−1
βg =2 η g − 23 (4π)
−(d−1)/2 φη e2 g2 ,
βλ = − 23 (4π)
−(d−1)/2 φη (e1 + λ e2) g
βg̃0 = − 2 g̃0 +4g
(4π)(d−1)/2
�b0 φη+1 − 1
6 e2 φη g̃0�,
βg̃1 =�2z − 2
�g̃1 +
2g3(4π)(d−1)/2
�b1 φη+1−1/z − e2 φη g̃1
�
βg̃2 = − 23 g̃2 +
g5π
�1
8√π
Γ(5/6)Γ(1/3) + g̃2
�,
βg̃3 = − 23 g̃3 +
g5π
�1
4√π
Γ(5/6)Γ(1/3) + g̃3
�,
βg̃i =gπ
�15 g̃i −
12 ci
�, i = {4, 5, 6, 7, 8}
wave-functionrenormalization {
Newton and cosmological constants
Higher derivativecouplings
{
{
Anisotropic Gaussian FP
Giulio D’Odorico ERG 2014 - 23 September 2014
g∗ = 0 , λ∗ = 1d
20000 40000 60000 80000 100000t
gi!t"
ci
20000 40000 60000 80000 100000t
!0.5
!0.4
!0.3
!0.2
!0.1
G!t"
1 2 3 4 5 t
!2."10!81
!1."10!81
1."10!81
2."10!81
#!t"!1#3
g̃∗1 = g̃∗2 = g̃∗3 = 0 , g̃∗i =5
2ci
c4 = 1336 , c5 = 1
840 , c6 = − 1560 ,
c7 = 1105 , c8 = − 1
180
Detailed Balance Revisited
Giulio D’Odorico ERG 2014 - 23 September 2014
• The Detailed Balance condition states that
Detailed Balance Revisited
Giulio D’Odorico ERG 2014 - 23 September 2014
V ∝ δW [σ]
δσijHijkl
δW [σ]
δσkl
• The Detailed Balance condition states that
• In d=3 this implies that the potential is the square of the Cotton tensor
Detailed Balance Revisited
Giulio D’Odorico ERG 2014 - 23 September 2014
V ∝ δW [σ]
δσijHijkl
δW [σ]
δσkl
Vdb ∝ CijCij
Cij = �iklDk
�Rj
l −14Rδjl
�
• The Detailed Balance condition states that
• In d=3 this implies that the potential is the square of the Cotton tensor
• Constructing the fixed point potential from the fixed point values of the couplings, one can see that it does not respect Detailed Balance
Detailed Balance Revisited
Giulio D’Odorico ERG 2014 - 23 September 2014
V ∝ δW [σ]
δσijHijkl
δW [σ]
δσkl
Vdb ∝ CijCij
Cij = �iklDk
�Rj
l −14Rδjl
�
Vdb ∝Rij∆xRij − 3
8R∆xR
+ 3RijR
jkR
ki − 5
2RRijRij +12R
3 VSV∗ = g∗4R∆xR− g∗5Rij∆xR
ij+
g∗6R3 + g∗7RRijR
ij + g∗8RijR
jkR
ki
CONCLUSIONS
Giulio D’Odorico ERG 2014 - 23 September 2014
• Evaluation of anisotropic Heat Kernels
• Large-N study of HL fixed point
Achievements
Giulio D’Odorico ERG 2014 - 23 September 2014
• Evaluation of anisotropic Heat Kernels
• Large-N study of HL fixed point
Achievements
Open Questions
• Flow portrait including higher spins (working on)
• Applications to other systems?
Giulio D’Odorico ERG 2014 - 23 September 2014
THANK YOU
APPENDIX
Giulio D’Odorico ERG 2014 - 23 September 2014
• Basic fields: Lapse, Shift, Induced metric
• Induced metric σ describes intrinsic curvature on the slice
• Lapse and shift describe extrinsic curvature
• EH action in ADM form (Gauss-Codazzi relation)
More on ADM
Giulio D’Odorico ERG 2014 - 23 September 2014
gµν �→ {N , Ni , σij }
Kij =1
2N{−σ̇ij +∇iNj +∇jNi}
SEH =
� �(KijKij −K2) +R
�√σ N d3x dt
• Notice that on general backgrounds:• Laplace transform:
• Split the exponential using the inverse Baker-Hausdorf (Zassenhaus) formula:
• Do another Laplace transform involving only the spatial Laplacian, and use Baker-Hausdorf again
• End up with:
• After a scale transformation, resum the two Laplacians into a “fake” covariant one. Then use Off-Diagonal techniques
Evaluating the Trace
Giulio D’Odorico ERG 2014 - 23 September 2014
[∆t,∆x] �= 0
et(X+Y ) � etX etY e−t2
2 [X,Y ] et3
6 (2[Y,[X,Y ]+[X,[X,Y ]]) · · ·
[∆t, (∆x)z]
exp (−s1∆t − s2∆x)
Trf�D2
�→ Tr e−sD2
Theory Space
limk→0
Γk[ϕ] = Γ[ϕ]limk→∞
Γk[ϕ] = S[ϕ]
k → 0
BARE
EA
The EAA interpolates smoothly between the bare action and the full quantum EA
Giulio D’Odorico ERG 2014 - 23 September 2014
Asymptotic Safety
•Gravity is perturbatively nonrenormalizable
•UV-completion: 1. New physics 2. Nonperturbative “self-healing”
• Generalized, nonperturbative renormalizability requirement
[GN ] = −2
Asymptotically Safe Theory:
‣ Has a (non-gaussian) RG fixed point
‣ The UV Critical Surface is finite dimensional
Giulio D’Odorico ERG 2014 - 23 September 2014