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Vector Beta Function. Yu Nakayama ( IPMU & Caltech ) arXiv:1310.0574. Vector Beta Function. Analogous to scalar beta function. Why do we care?. Poincare breaking: e.g. chemical potential Space-time dependent coupling const (localization, domain wall etc) - PowerPoint PPT Presentation
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Vector Beta Function
Yu Nakayama ( IPMU & Caltech)
arXiv:1310.0574
• Analogous to scalar beta function
Vector Beta Function
• Poincare breaking: e.g. chemical potential
• Space-time dependent coupling const (localization, domain wall etc)
• Renormalization of vector operators (vector meson, non-conserved current etc)
• Cosmology
• Condensed matter
• Holography
Why do we care?
Vector beta functions must satisfy
• Compensated gauge invariance
• Orthogonality
• Higgs-like relation with anomalous dimension
• Gradient property
• Non-renormalization
What I will show (or claim)
• General argument based on local renormalization group flow– Consistency conditions
• Direct computations– Conformal perturbation theories– Holography
How am I going to show?
• My argument is general
• I believe they are true in any sufficiently good relativistic field theories
• Beta functions should make sense
• To make the statement precise, I do assume powercounting renormalization scheme
• It should work also in Wilsonian sense…
Disclaimer
Consider renormalized Schwinger functional
A priori, vector beta function is expanded as
But, I claim it must be gauge covariant
1. Compensated gauge invariance
Scalar beta functions and vector beta functions are orthogonal
There are 72 such relations in standard model beta functions ( only depends on )
2. Orthogonality condition
We can compute anomalous dimensions of scalar operators and vector operators
3. Anomalous dimensions
: representation matrix of symmetry group G
Vector beta functions are generated as a gradient of the local gauge invariant functional
Cf: Scalar beta functions are generated by gradient flow (strong c-theorem)
4. Gradient property
Vector beta functions are zero if and only if the corresponding current is conserved.
5. Non-renormalization
Computation in conformal perturbation theory
Second order in perturbation
(Redundant) Conformal perturbation theory
• Compensated gauge invariance almost obvious from power-counting and current (non)-conservation
• Orthogonality
– Scalar beta function is gradient– C-function is gauge invariant
Checks 1
• Anomalous dimensions
• Gradient property
• Non-renormalization– Essentially Higgs effect
Checks 2
Local Renormalization Group Approach
• Renormalized Schwinger functional
• Action principle
• Local renormalization group operator
• Local Callan-Symanzik eq or trace identity
Local Renormalization Group
• Current non-conservation
• Compensated gauge invariance
• With this gauge (scheme) freedom, local renormalization group operator and beta functions are ambiguous
Gauge (scheme) ambiguity
• The choice
is very convenient because B=0 conformal• Alternatively, even for CFT, is possible by gauge (scheme) choice• Unless you compute vector beta functions, you
are uncertain…• You are (artificially) renormalizing the total
derivative term. The flow looks cyclic…
• But it IS CFT
Interlude: cyclic conformal flow?
• Simple observation (Osborn):
• For this to hold
• Consistency of Hamiltonian constraint
Integrability condition
• Start with local Callan-Symazik equation
• Act , and integrate over x once
Anomalous dimension formula
Anomalous dimensions
• From powercounting
• Gradient property requires
• Does this hold?
I don’t have a general proof, but it seems crucial in holography (S.S. Lee)
Gradient property (conj)
• Non-renormalization for conserved current
direction is a standard argument: conserved current is not renormalized
direction is more non-trivial. If H and G is non-singular, it must be true
• Closely related to scale vs conformal
Non-renormalization (conj)
A bit on Holographic computation
• Non-conserved current Spontaneously broken gauge theory in bulk
• For simplicity I’ll consider fixed AdS
• In a gauge
• For sigma model with potential
Vector beta functions in holography
• Relate 2nd order diff 1st order RG eq– Hamilton-Jacobi method– CGO singular perturbation with RG improvem
ent method
• Similar to (super)potential flow
Vector beta functions in holography
• Gauge invariance– d-dim invariance is obvious– What is d+1-dim gauge transformation?
• This leads to apparent cyclic flow for AdS space-time.
Check 1
• Orthogonality– Gauge invariance of (super)potential
• Anomalous dimensions massive vector from bulk Higgs mechanism
Check 2
• Gradient property– Radial Lagrangian potential functional– Partly conjectured by S.S Lee
• Non-renormalization– Common lore from unitarity– Higgs mechanism Massive vector– Massive vector Higgs mechanism– Can be broken at the sacrifice of NEC…
Check 3
Conclusion
• To be studied more– 72 functions to be computed in standard mod
el– What is variation of potential functional with re
spect to ?– New fixed points? Domain walls?– Any monotonicity?
Vector Beta Function