JHEP10(2017)108
holographic renormalization group appl i e d to theories known to possess l ocal holographic
duals (see for instance [
11] or [12] for a more recent overview).
In this work, such a geometerization of the RG flow triggered by the so called T
¯
T
operator in two dimensional conformal field theories with large central charge is presente d.
This will require the renormalization gr oup flow to be cast into the dynamics of general
relativity in one higher dimension. This happens through constructing the off shell action
for the bulk gravity t he or y. The tool used for this mapping is known as quantum RG
([
9, 13]). This however need be supplemente d with additional consistency conditions. These
conditions stem from the demand that the bulk theory be generally covariant. In order
for this to be the case the emergent bulk direction must be treated on equal footi n g with
those of the boundary theory.
I will provide a rough description of the techniques utilised for this quantum RG
mapping to transform renormalization group flows into a dynamical theory in one higher
dimension. We are typically interested in field theories in the bulk, so in order for the
renormalization group flow equations to mimic equations of motion, coupling constants
must be upgraded to sources which depend on space. The coarse graining transformations
in all ge ne r al i ty can act through Weyl transformations of t he background metric. This is
much akin to how coarse graining is manifested through Kadanoff’s blocking transformation
on lattice systems. The response of the generating functional of the quantum field theory
on said backgrou nd t o such a Weyl transformation shall determine the flow equations and
is thus the local variant of the Callan-Symanzik equation. This approach is known as the
local renormalization group, due to Osborn et al. [
10].
This local renormalization group is typically supplemented wi t h consistency con di ti on s
that encode the commutativity of the local Weyl transformations of the background metric.
These consistency conditions are kn own as the Wes s-Z umi n o conditions:
[∆
σ
, ∆
σ
′
]lnZ = 0,
where Z denotes the parti t i on function of the theory of interest and ∆
σ
is the generator
of infinitesimal local RG transformations. The property of general covariance in the bulk
theory is encoded as a particular form of the Wess-Zumino consi st e nc y conditions. As I will
argue in section 3, theories possessing local bulk duals ne ce ss ar i l y satisfy this condition-
which I call the holographic Wess-Zumino consistency condition [
8]. This cond i ti on will
be linchpin to properl y constructing the bulk gravity theory off shell in the large ce ntral
charge limit of the conformal field theory deformed by a composite operator of the stress
tensor mentioned earlier.
The article is organised as follows. Section 2 is devoted to laying out the field theoretic
starting point upon which the rest of the work builds. This includes two dimensional confor-
mal field the or i e s on curved backgrounds and a preliminary description of the T
¯
T deforma-
tion and some of its properties such as the factorisation of its expectation value. Concepts
relating to local renormalization group pertinent to the construction of the bulk theory, such
as reinterpr e ti n g a certain anomalous Ward identity as the local Callan-Symanzik equation
are also described. The construction of the bulk gravity theory through the quantum RG
mapping of the RG flow of the T
¯
T deformed large c CFT is described in section 3. The
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