Testing asymptotically safe quantum gravity through coupling to dynamical matter · 2014-09-02 ·...
Transcript of Testing asymptotically safe quantum gravity through coupling to dynamical matter · 2014-09-02 ·...
Testing asymptotically safe quantum gravitythrough coupling to dynamical matter
Astrid Eichhorn
Perimeter Institute for Theoretical Physics
Experimental search for quantum gravity 2014, SISSA, Trieste
How to test quantum gravity experimentally?
“direct” quantum gravity signals: challenging...
(precision) data on particle physics available
experimental quantum gravity tests: Compatibility with matter
“Level 0” test:Is a given model of quantum spacetime compatible with the existence ofstandard model matter?
“Level 1” test:Can it accommodate new particles (dark matter, supersymmetry...)?
LHC, ADMX, ALPS... can test quantum gravity NOW
How to test quantum gravity experimentally?
“direct” quantum gravity signals: challenging...
(precision) data on particle physics available
experimental quantum gravity tests: Compatibility with matter
“Level 0” test:Is a given model of quantum spacetime compatible with the existence ofstandard model matter?
“Level 1” test:Can it accommodate new particles (dark matter, supersymmetry...)?
LHC, ADMX, ALPS... can test quantum gravity NOW
How to test quantum gravity experimentally?
“direct” quantum gravity signals: challenging...
(precision) data on particle physics available
experimental quantum gravity tests: Compatibility with matter
“Level 0” test:Is a given model of quantum spacetime compatible with the existence ofstandard model matter?
“Level 1” test:Can it accommodate new particles (dark matter, supersymmetry...)?
LHC, ADMX, ALPS... can test quantum gravity NOW
How to test quantum gravity experimentally?
“direct” quantum gravity signals: challenging...
(precision) data on particle physics available
experimental quantum gravity tests: Compatibility with matter
“Level 0” test:Is a given model of quantum spacetime compatible with the existence ofstandard model matter?
“Level 1” test:Can it accommodate new particles (dark matter, supersymmetry...)?
LHC, ADMX, ALPS... can test quantum gravity NOW
How to test quantum gravity experimentally?
“direct” quantum gravity signals: challenging...
(precision) data on particle physics available
experimental quantum gravity tests: Compatibility with matter
“Level 0” test:Is a given model of quantum spacetime compatible with the existence ofstandard model matter?
“Level 1” test:Can it accommodate new particles (dark matter, supersymmetry...)?
LHC, ADMX, ALPS... can test quantum gravity NOW
Asymptotic safety: quantum field theory of the metric
quantum fields: gravity:
→ quantum gravity:
spacetime fluctuations
?
quantum theory of gravity in the path-integral framework:
Goal:∫
spacetimes e i S →∫
spacetimes e−S
Asymptotic safety: quantum field theory of the metric
quantum fields: gravity:
→ quantum gravity:
spacetime fluctuations
?
quantum theory of gravity in the path-integral framework:
Goal:∫
spacetimes e i S →∫
spacetimes e−S
Asymptotic safety: quantum field theory of the metric
quantum fields: gravity:
→ quantum gravity:
spacetime fluctuations
?
quantum theory of gravity in the path-integral framework:
Goal:∫
spacetimes e i S →∫
spacetimes e− S
Asymptotic safety: quantum field theory of the metricgoal:
∫Dgµνe−S[gµν ]
−→∫p<k Dgµνe
−Γk [gµν ]
k → k + δk
g1
g2 g3
Γk
Γk-‐δk
⇒ running couplings GN(k), λ(k)...
[S. Bethke, 2009]
Asymptotic safety: quantum field theory of the metricgoal:
∫Dgµνe−S[gµν ]
−→∫p<k Dgµνe
−Γk [gµν ]
k → k + δk
g1
g2 g3
Γk
Γk-‐δk
⇒ running couplings GN(k), λ(k)...
[S. Bethke, 2009]
Asymptotic safety: quantum field theory of the metricgoal:
∫Dgµνe−S[gµν ]
−→∫p<k Dgµνe
−Γk [gµν ]
k → k + δk
g1
g2 g3
Γk
Γk-‐δk
⇒ running couplings GN(k), λ(k)...
[S. Bethke, 2009]
Effective vs. fundamental QFTsQuantum Electrodynamics:
k
e2HkL
Λ
running coupling diverges⇒ Λ is scale of “new physics”
Effective theory
Quantum Chromodynamics:
k
ΑHkL
asymptotic freedomno need for “new physics”
Fundamental theory
Effective vs. fundamental QFTsQuantum Electrodynamics:
k
e2HkL
Λ
running coupling diverges⇒ Λ is scale of “new physics”
Effective theory
Quantum Chromodynamics:
k
ΑHkL
asymptotic freedomno need for “new physics”
Fundamental theory
Effective vs. fundamental QFTsQuantum Electrodynamics:
k
e2HkL
Λ
running coupling diverges⇒ Λ is scale of “new physics”
Effective theory
Quantum Chromodynamics:
k
ΑHkL
asymptotic freedomno need for “new physics”
Fundamental theory
Asymptotic safety
βg = k∂kg(k)
gravity: [GN ] = −2
G
ΒG
Asymptotic safety
interacting fixed point [Weinberg,
1979]
Asymptotic safety
βg = k∂kg(k)gravity: [GN ] = −2
G
ΒG
Asymptotic safety
interacting fixed point [Weinberg,
1979]
Asymptotic safety
βg = k∂kg(k)gravity: [GN ] = −2
ææ G
ΒG
Asymptotic safety
interacting fixed point[Weinberg, 1979]
Asymptotically Safe Quantum Gravity: EvidenceΓk EH = −1
16πGN(k)
∫ √g(R − 2λ(k)) (Wetterich-equation)
G = GNk2 and λ = λ/k2
fixed point in dimensionless couplings → scale-free regime
-0.1 0.0 0.1 0.2 0.3 0.4 0.5
-0.1
0.0
0.1
0.2
0.3
0.4
Λ
G
[M. Reuter, 1996; M. Reuter, F.Saueressig, 2001; D. Litim, 2004]
Compatibility with observations:Semiclassical gravity?
trajectory with GN → constand λ → const and measuredvalues in infrared
Asymptotically Safe Quantum Gravity: EvidenceΓk EH = −1
16πGN(k)
∫ √g(R − 2λ(k)) (Wetterich-equation)
G = GNk2 and λ = λ/k2
fixed point in dimensionless couplings → scale-free regime
-0.1 0.0 0.1 0.2 0.3 0.4 0.5
-0.1
0.0
0.1
0.2
0.3
0.4
Λ
G
[M. Reuter, 1996; M. Reuter, F.Saueressig, 2001; D. Litim, 2004]
Compatibility with observations:Semiclassical gravity?
trajectory with GN → constand λ → const and measuredvalues in infrared
Asymptotically Safe Quantum Gravity: EvidenceΓk EH = −1
16πGN(k)
∫ √g(R − 2λ(k)) (Wetterich-equation)
G = GNk2 and λ = λ/k2
fixed point in dimensionless couplings → scale-free regime
-0.1 0.0 0.1 0.2 0.3 0.4 0.5
-0.1
0.0
0.1
0.2
0.3
0.4
Λ
G
[M. Reuter, 1996; M. Reuter, F.Saueressig, 2001; D. Litim, 2004]
Compatibility with observations:Semiclassical gravity?
trajectory with GN → constand λ → const and measuredvalues in infrared
Asymptotically Safe Quantum Gravity: EvidenceΓk EH = −1
16πGN(k)
∫ √g(R − 2λ(k))
G = GNk2 and λ = λ/k2
fixed point in dimensionless couplings → scale-free regime
-0.1 0.0 0.1 0.2 0.3 0.4 0.5
-0.1
0.0
0.1
0.2
0.3
0.4
Λ
G
[M. Reuter, 1996; M. Reuter, F.Saueressig, 2001; D. Litim, 2004]
Compatibility with observations:Semiclassical gravity?
trajectory with GN → constand λ → const and measuredvalues in infrared
Asymptotically Safe Quantum Gravity: Evidence
-0.1 0.0 0.1 0.2 0.3 0.4 0.5
-0.1
0.0
0.1
0.2
0.3
0.4
Λ
G
Γk EH = −116πGN(k)
∫ √g(R − 2λ(k))
fixed-point action: prediction
Γk = Γk EH + Γgauge−fixing + Γghost +∫ √
g (f (R) + RµνRµν + ....)
E. Manrique, M. Reuter, F. Saueressig (2009, 2010);
I. Donkin, J. Pawlowski (2012);
A. Codello, G. D’Odorico, C. Pagani (2013)
A.E., H.Gies, M.Scherer (2009), A.E., H. Gies (2010),
A.E. (2013)
A. Codello, R. Percacci, C. Rahmede (2008);
D.Benedetti, F. Caravelli (2012);
K. Falls, D. Litim, K. Nikolakopoulos (2013);
J. Dietz, T. Morris (2013);
M. Demmel, F. Saueressig, O. Zanusso (2014)
D. Benedetti, P. Machado, F. Saueressig (2009)
Asymptotically Safe Quantum Gravity: Evidence
-0.1 0.0 0.1 0.2 0.3 0.4 0.5
-0.1
0.0
0.1
0.2
0.3
0.4
Λ
G
Γk EH = −116πGN(k)
∫ √g(R − 2λ(k))
fixed-point action: prediction
Γk = Γk EH + Γgauge−fixing + Γghost +∫ √
g (f (R) + RµνRµν + ....)
E. Manrique, M. Reuter, F. Saueressig (2009, 2010);
I. Donkin, J. Pawlowski (2012);
A. Codello, G. D’Odorico, C. Pagani (2013)
A.E., H.Gies, M.Scherer (2009), A.E., H. Gies (2010),
A.E. (2013)
A. Codello, R. Percacci, C. Rahmede (2008);
D.Benedetti, F. Caravelli (2012);
K. Falls, D. Litim, K. Nikolakopoulos (2013);
J. Dietz, T. Morris (2013);
M. Demmel, F. Saueressig, O. Zanusso (2014)
D. Benedetti, P. Machado, F. Saueressig (2009)
What matters in quantum gravity
Universe contains gravity & matter
interaction between these cannot be switched off
∫ddx√ggµν∂µφ∂νφ −→ ...
RG flow in gravity and matter sector driven by metric & matterfluctuations ⇒ gravity and matter matters!
What matters in quantum gravity
Universe contains gravity & matter
interaction between these cannot be switched off
∫ddx√ggµν∂µφ∂νφ −→ ...
RG flow in gravity and matter sector driven by metric & matterfluctuations ⇒ gravity and matter matters!
What matters in quantum gravity
Universe contains gravity & matter
interaction between these cannot be switched off
∫ddx√ggµν∂µφ∂νφ −→ ...
RG flow in gravity and matter sector driven by metric & matterfluctuations ⇒ gravity and matter matters!
Learning by example: Possible effects of matterQuantum Chromodynamics:
0.4 0.8 g
-0.01
0.01
bgQCD
Nf < 16.5
Nf > 16.5
Asymptotic freedom only for Nf < 16.5
UV completion for gravity compatible with Standard Model?
Learning by example: Possible effects of matterQuantum Chromodynamics:
0.4 0.8 g
-0.01
0.01
bgQCD
Nf < 16.5
Nf > 16.5
Asymptotic freedom only for Nf < 16.5
UV completion for gravity compatible with Standard Model?
Matter effects on the gravitational fixed pointwith P. Dona, R. Percacci (2013): Truncation of the effective action:
Γk = Γk EH + Γk matter
Γk EH = −116πGN(k)
∫ √g(R − 2λ(k)) + Zh
2
∫ √ghµνMµνκλ
(−D2
)hκλ
ηh = −k∂k lnZh
βG , βλ
Matter effects on the gravitational fixed pointwith P. Dona, R. Percacci (2013): Truncation of the effective action:
Γk = Γk EH + Γk matter
Γk EH = −116πGN(k)
∫ √g(R − 2λ(k)) + Zh
2
∫ √ghµνMµνκλ
(−D2
)hκλ
ηh = −k∂k lnZh
βG , βλ
Matter effects on the gravitational fixed pointwith P. Dona, R. Percacci (2013): Truncation of the effective action:
Γk = Γk EH + Γk matter
Γk EH = −116πGN(k)
∫ √g(R − 2λ(k)) + Zh
2
∫ √ghµνMµνκλ
(−D2
)hκλ
ηh = −k∂k lnZh
βG , βλ
Matter effects on the gravitational fixed pointwith P. Dona, R. Percacci (2013): Truncation of the effective action:
Γk = Γk EH + Γk matter with minimally coupled matter:
NS scalars: SS = ZS2
∫ddx√g gµν
∑Nsi=1 ∂µφ
i∂νφi
ηS = −k∂k lnZSηh
βG , βλ
Matter effects on the gravitational fixed pointwith P. Dona, R. Percacci (2013): Truncation of the effective action:
Γk = Γk EH + Γk matter with minimally coupled matter:
NS scalars: SS = ZS2
∫ddx√g gµν
∑Nsi=1 ∂µφ
i∂νφi
ηS = −k∂k lnZS
ηh
βG , βλ
Matter effects on the gravitational fixed pointwith P. Dona, R. Percacci (2013): Truncation of the effective action:
Γk = Γk EH + Γk matter with minimally coupled matter:
NS scalars: SS = ZS2
∫ddx√g gµν
∑Nsi=1 ∂µφ
i∂νφi
ηS = −k∂k lnZSηh
βG , βλ
Matter effects on the gravitational fixed pointwith P. Dona, R. Percacci (2013): Truncation of the effective action:
Γk = Γk EH + Γk matter with minimally coupled matter:
ND Dirac fermions SD = iZD
∫ddx√g∑ND
i=1 ψi /∇ψi
ηD = −k∂k lnZD
ηh
βG , βλ
Matter effects on the gravitational fixed pointwith P. Dona, R. Percacci (2013): Truncation of the effective action:
Γk = Γk EH + Γk matter with minimally coupled matter:
ND Dirac fermions SD = iZD
∫ddx√g∑ND
i=1 ψi /∇ψi
ηD = −k∂k lnZDηh
βG , βλ
Matter effects on the gravitational fixed pointwith P. Dona, R. Percacci (2013): Truncation of the effective action:
Γk = Γk EH + Γk matter with minimally coupled matter:
NV Abelian vector bosons:SV = ZV
4
∫ddx√g∑NF
i=1 gµνgκλF i
µκFiνλ + ZV
2ξ
∫ddx√g∑NF
i=1
(gµνDµA
iν
)2
ηV = −k∂k lnZV
ηh
βG , βλ
Matter effects on the gravitational fixed pointwith P. Dona, R. Percacci (2013): Truncation of the effective action:
Γk = Γk EH + Γk matter with minimally coupled matter:
NV Abelian vector bosons:SV = ZV
4
∫ddx√g∑NF
i=1 gµνgκλF i
µκFiνλ + ZV
2ξ
∫ddx√g∑NF
i=1
(gµνDµA
iν
)2
ηV = −k∂k lnZV
ηh
βG , βλ
Matter effects on the gravitational fixed point
→ βG , βλ, ηh
ηc , ηS , ηD , ηV
-0.1 0.0 0.1 0.2 0.3 0.4 0.5
-0.1
0.0
0.1
0.2
0.3
0.4
Λ
G???
Is the fixed point compatible with the standard model?
Perturbative analysis(neglect graviton and matter wave function renormalizations)
βG = 2G + G2
6π (
NS + 2ND − 4NV
− 46) ,
→ for a given number of vectors NV , there is an upper limit on thenumber of scalars NS and Dirac fermions ND !
Matter matters in asymptotically safe quantum gravity!
Perturbative analysis(neglect graviton and matter wave function renormalizations)
βG = 2G + G2
6π (NS + 2ND − 4NV − 46) ,
→ for a given number of vectors NV , there is an upper limit on thenumber of scalars NS and Dirac fermions ND !
Matter matters in asymptotically safe quantum gravity!
Perturbative analysis(neglect graviton and matter wave function renormalizations)
βG = 2G + G2
6π (NS + 2ND − 4NV − 46) ,
→ for a given number of vectors NV , there is an upper limit on thenumber of scalars NS and Dirac fermions ND !
Matter matters in asymptotically safe quantum gravity!
Perturbative analysis(neglect graviton and matter wave function renormalizations)
βG = 2G + G2
6π (NS + 2ND − 4NV − 46) ,
→ for a given number of vectors NV , there is an upper limit on thenumber of scalars NS and Dirac fermions ND !
Matter matters in asymptotically safe quantum gravity!
Fermions, scalars and the fixed point
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2 4 6 8ND
-10
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scalars & fermions drive G∗ to divergence ⇒ upper limit on NS ,ND
Fermions, scalars and the fixed point
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scalars & fermions drive G∗ to divergence ⇒ upper limit on NS ,ND
Vectors and the fixed point
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0.05
0.10
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0.25
0.30
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vector degrees of freedom unrestricted by fixed-point requirement
Full analysis for NV = 12
10 20 30 40 50 60 70NS
10
20
30
40
ND
upper limit on ND and NS
Standard Model: NV = 12, ND = 45/2, NS = 4:compatible with gravitational fixed point
Specific matter models
Standard Model: (NS = 4,ND = 45/2,NV = 12) X
→ right-handed neutrinos?X
→ dark matter scalar? X
→ axion? X
supersymmetric extension (MSSM: NS = 49,ND = 61/2,NV = 12) 7
GUT (SO(10): NS = 97,ND = 24,NV = 45) 7
Only specific models with restricted matter content are compatible withAsymptotically Safe Quantum Gravity within our truncation
Specific matter models
Standard Model: (NS = 4,ND = 45/2,NV = 12) X
→ right-handed neutrinos?X
→ dark matter scalar? X
→ axion? X
supersymmetric extension (MSSM: NS = 49,ND = 61/2,NV = 12) 7
GUT (SO(10): NS = 97,ND = 24,NV = 45) 7
Only specific models with restricted matter content are compatible withAsymptotically Safe Quantum Gravity within our truncation
Specific matter models
Standard Model: (NS = 4,ND = 45/2,NV = 12) X
→ right-handed neutrinos?X
→ dark matter scalar? X
→ axion? X
supersymmetric extension (MSSM: NS = 49,ND = 61/2,NV = 12) 7
GUT (SO(10): NS = 97,ND = 24,NV = 45) 7
Only specific models with restricted matter content are compatible withAsymptotically Safe Quantum Gravity within our truncation
Specific matter models
Standard Model: (NS = 4,ND = 45/2,NV = 12) X
→ right-handed neutrinos?X
→ dark matter scalar? X
→ axion? X
supersymmetric extension (MSSM: NS = 49,ND = 61/2,NV = 12) 7
GUT (SO(10): NS = 97,ND = 24,NV = 45) 7
Only specific models with restricted matter content are compatible withAsymptotically Safe Quantum Gravity within our truncation
Specific matter models
Standard Model: (NS = 4,ND = 45/2,NV = 12) X
→ right-handed neutrinos?X
→ dark matter scalar? X
→ axion? X
supersymmetric extension (MSSM: NS = 49,ND = 61/2,NV = 12) 7
GUT (SO(10): NS = 97,ND = 24,NV = 45) 7
Only specific models with restricted matter content are compatible withAsymptotically Safe Quantum Gravity within our truncation
Tests of quantum gravity
Does testing quantum gravity require galaxy-size accelerators?
Possibly could test Asymptotically Safe Quantum Gravity at LHC, 14 TeV:Look for Beyond-Standard-Model particle physics
experimental searches for weakly-coupled low-mass particles (dark matter)might also test quantum gravity
Extra dimensions
[J. Pivarski]
Extra dimensions in asymptotic safety?
pure-gravity fixed point exists in d ≥ 4
(Einstein-Hilbert [Fischer, Litim, 2006] and higherderivatives [Ohta, Percacci, 2013])
10 20 30 40 50 60NS
5
10
15
20
25
N D
10 20 30 40 50 60NS
2
4
6
8
10N D
5d 6d
→ universal extra dimensions restricted [P.Dona, A.E., R. Percacci, 2013]
Extra dimensions
[J. Pivarski]
Extra dimensions in asymptotic safety?
pure-gravity fixed point exists in d ≥ 4
(Einstein-Hilbert [Fischer, Litim, 2006] and higherderivatives [Ohta, Percacci, 2013])
10 20 30 40 50 60NS
5
10
15
20
25
N D
10 20 30 40 50 60NS
2
4
6
8
10N D
5d 6d
→ universal extra dimensions restricted [P.Dona, A.E., R. Percacci, 2013]
Extra dimensions
[J. Pivarski]
Extra dimensions in asymptotic safety?
pure-gravity fixed point exists in d ≥ 4
(Einstein-Hilbert [Fischer, Litim, 2006] and higherderivatives [Ohta, Percacci, 2013])
10 20 30 40 50 60NS
5
10
15
20
25
N D
10 20 30 40 50 60NS
2
4
6
8
10N D
5d 6d
→ universal extra dimensions restricted [P.Dona, A.E., R. Percacci, 2013]
The Higgs – new compatibility tests for quantum gravity?
Higgs mass mH ∼√λ4
L
l4
λ4 æ
æ
æ
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æ
æ
æ
æ
ææ
ææ
107 109 1011 1013 1015 1017 1019
140.
145.
150.
155.
160.
L�GeV
mH
�G
eV
Higgs mass bound in toy model
Where is Planck-scale physics/ quantum gravity?
underlying assumption: Vφ(Λ) = m2φ2 + λ4φ4 + λ6φ
6 + ... withλ6(Λ) = λ8(Λ) = 0
quantum gravity:
The Higgs – new compatibility tests for quantum gravity?Higgs mass mH ∼
√λ4
L
l4
λ4
æ
æ
æ
æ
æ
æ
æ
æ
æ
ææ
ææ
107 109 1011 1013 1015 1017 1019
140.
145.
150.
155.
160.
L�GeV
mH
�G
eV
Higgs mass bound in toy model
Where is Planck-scale physics/ quantum gravity?
underlying assumption: Vφ(Λ) = m2φ2 + λ4φ4 + λ6φ
6 + ... withλ6(Λ) = λ8(Λ) = 0
quantum gravity:
The Higgs – new compatibility tests for quantum gravity?Higgs mass mH ∼
√λ4
L
l4
λ4 æ
æ
æ
æ
æ
æ
æ
æ
æ
ææ
ææ
107 109 1011 1013 1015 1017 1019
140.
145.
150.
155.
160.
L�GeV
mH
�G
eV
Higgs mass bound in toy model
Where is Planck-scale physics/ quantum gravity?
underlying assumption: Vφ(Λ) = m2φ2 + λ4φ4 + λ6φ
6 + ... withλ6(Λ) = λ8(Λ) = 0
quantum gravity:
The Higgs – new compatibility tests for quantum gravity?Higgs mass mH ∼
√λ4
L
l4
λ4 æ
æ
æ
æ
æ
æ
æ
æ
æ
ææ
ææ
107 109 1011 1013 1015 1017 1019
140.
145.
150.
155.
160.
L�GeV
mH
�G
eV
Higgs mass bound in toy model
Where is Planck-scale physics/ quantum gravity?
underlying assumption: Vφ(Λ) = m2φ2 + λ4φ4 + λ6φ
6 + ... withλ6(Λ) = λ8(Λ) = 0
quantum gravity:
The Higgs – new compatibility tests for quantum gravity?Higgs mass mH ∼
√λ4
L
l4
λ4 æ
æ
æ
æ
æ
æ
æ
æ
æ
ææ
ææ
107 109 1011 1013 1015 1017 1019
140.
145.
150.
155.
160.
L�GeV
mH
�G
eV
Higgs mass bound in toy model
Where is Planck-scale physics/ quantum gravity?
underlying assumption: Vφ(Λ) = m2φ2 + λ4φ4 + λ6φ
6 + ... withλ6(Λ) = λ8(Λ) = 0
quantum gravity:
Higgs mass and Planck-scale physicsexpect from Planck-scale physics (quantum gravity): λ6(Λ) 6= 0, λ8(Λ) 6= 0
example: λi (Λ) = 0, λ4(Λ) = 0, λ6(Λ) = 3, λ4(Λ) = −0.1, λ6(Λ) = 2
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107 109 1011 1013 1015 1017 1019125.
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[A.E., M. Scherer, 2014& A.E., J. Jackel, T. Plehn and M. Scherer,in progress]
Higgs mass sensitive to UV physics!
Outlook: predict Higgs mass from quantum gravity, compare to measuredvalue mH ≈ 125GeV
Higgs mass and Planck-scale physicsexpect from Planck-scale physics (quantum gravity): λ6(Λ) 6= 0, λ8(Λ) 6= 0
example: λi (Λ) = 0, λ4(Λ) = 0, λ6(Λ) = 3, λ4(Λ) = −0.1, λ6(Λ) = 2
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107 109 1011 1013 1015 1017 1019125.
130.
135.
140.
145.
150.
155.160.
L�GeV
mH
�G
eV
[A.E., M. Scherer, 2014& A.E., J. Jackel, T. Plehn and M. Scherer,in progress]
Higgs mass sensitive to UV physics!
Outlook: predict Higgs mass from quantum gravity, compare to measuredvalue mH ≈ 125GeV
Summary & Outlook
Matter matters in (asymptotically safe) quantum gravity
Asymptotic safety only viable for standard model and “small”extensions within truncated RG flow (unless assume very largenumber of vectors)
Experimental tests of quantum gravity possible (search forBeyond-Standard-Model physics at LHC and low-mass particle searchexperiments)
Outlook: Higgs mass sensitive to UV physics: New test for quantumgravity!
Thank you for your attention!
Summary & Outlook
Matter matters in (asymptotically safe) quantum gravity
Asymptotic safety only viable for standard model and “small”extensions within truncated RG flow (unless assume very largenumber of vectors)
Experimental tests of quantum gravity possible (search forBeyond-Standard-Model physics at LHC and low-mass particle searchexperiments)
Outlook: Higgs mass sensitive to UV physics: New test for quantumgravity!
Thank you for your attention!
Setting a scale in quantum gravityRG: sort quantum fluctuations according to momentum
flat background: p2 curved background: D2
fluctuating spacetime?
background field method: gµν = gµν + hµν∫Dgµνe−S[gµν ] =
∫Dhµνe−S[gµν+hµν ]
D2 → short/long wavelength quantumfluctuations → hµν Rk(D2) hµν
action symmetric under gµν → gµν + εγµν , hµν → hµν − εγµν
broken by regulator! ⇒ background couplings 6= fluctuation couplings
Setting a scale in quantum gravityRG: sort quantum fluctuations according to momentum
flat background: p2 curved background: D2
fluctuating spacetime?
background field method: gµν = gµν + hµν∫Dgµνe−S[gµν ] =
∫Dhµνe−S[gµν+hµν ]
D2 → short/long wavelength quantumfluctuations → hµν Rk(D2) hµν
action symmetric under gµν → gµν + εγµν , hµν → hµν − εγµν
broken by regulator! ⇒ background couplings 6= fluctuation couplings
Setting a scale in quantum gravityRG: sort quantum fluctuations according to momentum
flat background: p2 curved background: D2
fluctuating spacetime?
background field method: gµν = gµν + hµν∫Dgµνe−S[gµν ] =
∫Dhµνe−S[gµν+hµν ]
D2 → short/long wavelength quantumfluctuations → hµν Rk(D2) hµν
action symmetric under gµν → gµν + εγµν , hµν → hµν − εγµν
broken by regulator! ⇒ background couplings 6= fluctuation couplings