Searcharxiv⌕ Search

arXiv subjects

Anastasios C. Petkou

Publications and source records attributed to Anastasios C. Petkou.

43 records · Page 3Linked to original sources
arXiv2007

Conformally Coupled Scalars, Instantons and Vacuum Instability in AdS_4

We show that a scalar field conformally coupled to AdS gravity in four dimensions with a quartic self-interaction can be embedded into M-theory. The holographic effective potential is exactly calculated, allowing us to study non-perturbatively the stability of AdS_4 in the presence of the conformally coupled scalar. It is shown that there exists a one-parameter family of conformal scalar boundary conditions for which the boundary theory has an unstable vacuum. In this case, the bulk theory has instanton solutions that mediate the decay of the AdS_4 space. These results match nicely with the vacuum structure and the existence of instantons in an effective three-dimensional boundary model.

hep-th↗
arXiv2007

Instantons and Conformal Holography

We study a subsector of the AdS_4/CFT_3 correspondence where a class of solutions in the bulk and on the boundary can be explicitly compared. The bulk gravitational theory contains a conformally coupled scalar field with a Phi^4 potential, and is holographically related to a massless scalar with a Phi^6 interaction in three dimensions. We consider the scalar sector of the bulk theory and match bulk and boundary classical solutions of the equations of motion. Of particular interest is the matching of the bulk and the boundary instanton solutions which underlies the relationship between bulk and boundary vacua with broken conformal invariance. Using a form of radial quantization we show that quantum states in the bulk correspond to multiply-occupied single particle quantum states in the boundary theory. This allows us to explicitly identify the boundary composite operator which is dual to the bulk scalar, at the free theory level as well as in the instanton vacuum. We conclude with a discussion of possible implications of our results.

hep-th↗
arXiv2006

Noncritical M-theory and the Gross-Neveu model in 2+1 dimensions

We point out a non-trivial connection between the model proposed by Horava and Keeler as a candidate for noncritical M-theory and the Gross-Neveu model with fermionic fields obeying periodic boundary conditions in 2+1 dimensions. Specifically, the vacuum energy of the former is identified with the large-N free-energy of the latter up to an overall constant. This identification involves an appropriate analytic continuation of the subtraction point in noncritical M-theory, which is related to the volume of the Liouville dimension. We show how the world-sheet cosmological constant may be obtained from the Gross-Neveu model. At its critical point, which is given in terms of the golden mean, the values of the vacuum energy and of the cosmological constant are 4/5 and 2/5 of the corresponding values at infinite string coupling constant.

hep-th↗
arXiv2003

SL(2,Z) Action on Three-Dimensional CFTs and Holography

We show that there is a natural action of SL(2,Z) on the two-point functions of the energy momentum tensor and of higher-spin conserved currents in three-dimensional CFTs. The dynamics behind the S-operation of SL(2,Z) is that of an irrelevant current-current deformation and we point out its similarity to the dynamics of a wide class of three-dimensional CFTs. The holographic interpretation of our results raises the possibility that many three-dimensional CFTs have duals on AdS4 with SL(2,Z) duality properties at the linearized level.

hep-th↗
arXiv2000

Renormalization Group Flow and Thermodynamics of Conformal Field Theories

We discuss the free-energy density of bosonic and fermionic theories possessing strongly coupled critical points in D=3. We construct a stationary renormalization group trajectory which interpolates between the free massless theory of N scalars and a class of interacting theories including both bosons and fermions. At a special point of this trajectory the free-energy density is 5/4 times the free-energy density of the O(N) vector model at its nontrivial critical point. Our method could in principle be useful in the study of other theories with strongly coupled fixed points, such as {\cal N}=4 SYM in D=4.

hep-th↗
arXiv1998

Finite-Size and Finite-Temperature Effects in the Conformally Invariant O(N) Vector Model for 2<d<4

We study the operator product expansion (OPE) of the auxiliary scalar field λ(x) with itself, in the conformally invariant O(N) Vector Model for 2<d<4, to leading order in 1/N in a strip-like geometry with one finite dimension of length L. We show that consistency of the finite-geometry OPE with bulk OPE calculations requires the physical conditions of, either finite-size scaling at criticality, or finite-temperature phase transition.

hep-th↗