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I. Lovrekovic

Publications and source records attributed to I. Lovrekovic.

16 recordsLinked to original sources

Holography of New Conformal Higher Spin Gravities in 3d

We study the holography of the new conformal higher spin theories imposing general boundary conditions and the near horizon boundary conditions. General boundary conditions lead to the asymptotic symmetry algebra which is a loop algebra of the underlying gauge algebra. The near horizon boundary conditions give u(1) currents at the boundary. For each of the boundary conditions we consider an example of conformal graviton, and its combination with a vector, and a spin-3 field, respectively. The near horizon boundary conditions lead to three dimensional Banados-Teitelboim- Zanelli (BTZ)-like black hole which can have up to four real eigenvalues, Lobachevsky solution, and to generalisation of that BTZ-like solution.

hep-th

A note on one-parameter subgroups of SO(3,2)

We analyze the structure of one-parameter subgroups of SO(3,2). We find two new types of subgroups in comparison with the structure of the one-parameter subgroups of SO(2,2), and we construct explicit examples for these subgroups. We also comment on the placement of existing conformal gravity solutions within this classification.

hep-th

Holography of new conformal higher spin gravities in 3d for low spins

We study holography of the 3d Chern-Simons theory as a gauge theory of $so(3,2)$, $sl_4$ and $sl_5$ algebras. For the near horizon boundary conditions we comment solutions from several projectors from Chern-Simons to the metric formulation. These solutions are generalized BTZ solutions for our theories. We also study the classification according to $so(3,2)$ one parameter subgroups for obtained solutions.

hep-th

Conformal Galilean Spin-3 Gravity in 3d

We consider Galilean limit of conformal algebra for spin-2 and spin-3 fields, and study the gauge theory of these algebras. We analyze the equations of motion and obtain the spectra of the theories.

hep-th

Conformal Carrollian Spin-3 Gravity in 3d

We consider ultra-relativistic limit of the spin-2 and spin-3 conformal gravity theories in three dimensions, which leads to conformal Carrollian spin-2 gravity and its spin-3 analog. We also comment on the generalization of the result to arbitrary spin. The holographic examples show generalization in comparison with non-conformal Carrollian gravity.

hep-th

Holography of pp-waves in conformal gravity

We consider holography of two pp-wave metrics in conformal gravity, their one point functions, and asymptotic symmetries. One of the metrics is a generalization of the standard pp-waves in Einstein gravity to conformal gravity. The holography of this metric shows that within conformal gravity one can have realised solution which has non-vanishing partially massless response (PMR) tensor even for vanishing subleading term in the Fefferman-Graham expansion (i.e. Neumann boundary conditions), and vice-versa.

hep-th

On two-vierbein gravity action from gauge theory of conformal group

We study the gravity action built from two gauge fields corresponding to the generators of the conformal group. Starting with the action from which one can obtain Einstein gravity and conformal gravity upon imposing suitable constraints, we keep two independent gauge fields and integrate out the field corresponding to the generator of Lorentz transformations. We identify the two gauge fields with two vierbeins and perturb them around an Anti--de Sitter space. This gives the linearized equations that differ from both, Einstein gravity and conformal gravity linearized equations. We also study the linearized equations for one gauge field perturbed around the flat space and one around zero, and the case when the gauge fields are proportional to each other.

hep-th

Coupling coefficient in three dimensional higher spin holography

We consider linearised Vasiliev's equations around the background AdS field in three dimensions for the scalar-scalar-higher spin field correlation function. Relating this with the higher spin field determined in the metric formulation allows determination of the corresponding coupling coefficient. The result agrees with the analogous computation for the spin three field.

hep-th

Asymptotic symmetry algebra of conformal gravity

We compute asymptotic symmetry algebras of conformal gravity. Due to more general boundary conditions allowed in conformal gravity in comparison to those in Einstein gravity, we can classify the corresponding algebras. The highest algebra for non-trivial boundary conditions is five dimensional and it leads to global geon solution with non-vanishing charges.

hep-th

Classical and holographic aspects of conformal gravity in four dimensions

We formulate new boundary conditions that prove well defined variational principle and finite response functions for conformal gravity (CG). In the Anti--de Sitter/conformal field theory framework, gravity theory that is considered in the bulk gives information about the corresponding boundary theory. The metric is split in the holographic coordinate, used to approach the boundary, and the metric at the boundary. One can consider the quantities in the bulk perturbing the (one dimension lower) boundary metric in holographic coordinate. The response functions to fluctuations of the boundary metric are Brown--York stress energy tensor sourced by the leading term in the expansion of the boundary metric and a Partially Massless Response, specific for CG and sourced by the subleading term in the expansion of the boundary metric. They formulate boundary charges that define the asymptotic symmetry algebra or the algebra of the diffeomorphisms that preserve the boundary conditions of the theory. We further analyse CG via canonical analysis constructing the gauge generators of the canonical charges that agree with Noether charges, while the charge associated to Weyl transformations, vanishes. Asymptotic symmetry algebra is determined by the leading term in the expansion of the boundary metric and for the asymptotically Minkowski, R \times S2, and the boundaries related by conformal rescaling, defines conformal algebra. The key role is played by the subleading term in the expansion of the metric forbidden by Einstein gravity equations of motion, however allowed in CG. We classify the subalgebras of conformal algebra restricted by this term and use them to deduce the global solutions of CG. Further, we compute the one loop partition function of CG in four and six dimensions and obtain its structure.

hep-th

One loop partition function of six dimensional conformal gravity using heat kernel on AdS

We compute the heat kernel for the Laplacians of symmetric transverse traceless fields of arbitrary spin on the $AdS$ background in even number of dimensions using the group theoretic approach introduced in \cite{Gopakumar:2011qs} and apply it on the partition function of six dimensional conformal gravity. The obtained partition function consists of the Einstein gravity, conformal ghost and two modes that contain mass.

hep-th

Conformal gravity 1-loop partition function

We evaluate the 1-loop partition function of conformal gravity in four dimensions around an $AdS_4$ background, using the heat kernel techniques. We give expressions for the relevant thermodynamical quantities and compare our results with the ones from the literature.

hep-th

Canonical charges and asymptotic symmetries in four dimensional conformal gravity

We calculate canonical charges in four dimensional conformal gravity using the generalised boundary conditions presented in \cite{Grumiller:2013mxa}. We show that the charges are finite and conserved. The asymptotic symmetry algebras generated by these charges are classified according to the conditions imposed on the first subleading term in the generalised Fefferman-Graham expansion.

hep-th

Conformal gravity holography in four dimensions

We formulate four-dimensional conformal gravity with (Anti-)de Sitter boundary conditions that are weaker than Starobinsky boundary conditions, allowing for an asymptotically subleading Rindler term concurrent with a recent model for gravity at large distances. We prove the consistency of the variational principle and derive the holographic response functions. One of them is the conformal gravity version of the Brown-York stress tensor, the other is a `partially massless response'. The on-shell action and response functions are finite and do not require holographic renormalization. Finally, we discuss phenomenologically interesting examples, including the most general spherically symmetric solutions and rotating black hole solutions with partially massless hair.

hep-th

Dark Matter from Q4 Extension of Standard Model

Recent analysis of spontaneous breaking of SU(2) as a continuous gauged flavor symmetry to non-abelian discrete group Q4 as a residual symmetry motivates its consideration as a group for stabilizing dark matter. We determine the region of hidden sector particles compatible with relic dark matter density and present prospects in which these particles could be observed using direct and indirect dark matter search experiments.

hep-ph