arXiv subjects
Publications and source records attributed to Sergei D. Odintsov.
The construction of the linearized four-dimensional multisupergravity from five-dimensional linearized supergravity with discretized fifth dimension is presented. The one-loop vacuum energy is evaluated when (anti)periodic boundary conditions are chosen for (bosons) fermions, respectively or vice-versa. It is proposed that the relation between discretized M-theory and strings may be found in the same fashion.
There exists a freedom in a class of four-dimensional electroweak theories proposed by Arkani-Hamed et al. relying on deconstruction and Coleman-Weinberg mechanism. The freedom comes from the winding modes of the link variable (Wilson operator) connecting non-nearest neighbours in the discrete fifth dimension. Using this freedom, dynamical breaking of SU(2) gauge symmetry, mass hierarchy patterns of fermions and Cabbibo-Kobayashi-Maskawa matrix may be obtained.
The modified gravity with $\ln R$ or $R^{-n} (\ln R)^m$ terms which grow at small curvature is discussed. It is shown that such a model which has well-defined newtonian limit may eliminate the need for dark energy and may provide the current cosmic acceleration. It is demonstrated that $R^2$ terms are important not only for early time inflation but also to avoid the instabilities and the linear growth of the gravitational force. It is very interesting that the condition of no linear growth for gravitational force coincides with the one for scalar mass in the equivalent scalar-tensor theory to be very large. Thus, modified gravity with $R^2$ term seems to be viable classical theory.
We calculate the difference of one-loop vacuum energies for massive scalar field in five-dimensional AdS black hole. (The same is done in five-dimensional deSitter space). In each case this difference is specified by the boundary conditions corresponding to the double-trace operator (massive term) and it describes RG flow in the manner discussed by Gubser-Mitra for pure AdS space. For AdS black hole there occurs instability which is the manifestation of the Hawking-Page phase transition. For stable phase of AdS black hole as well as for deSitter bulk, c-function found beyond the leading order approximation shows the monotonic behaviour consistent with c-theorem.
We study classes of five-dimensional cosmological solutions with negative curvature, which are obtained from static solutions by an exchange of a spatial and temporal coordinate, and in some cases by an analytic continuation. Such solutions provide a suitable laboratory to address the time-dependent AdS/CFT correspondence. For a specific example we address in detail the calculation of the boundary stress-energy and the Wilson line and find disagreement with the standard AdS/CFT correspondence. We trace these discrepancies to the time-dependent effects, such as particle creation, which we further study for specific backgrounds. We also identify specific time-dependent backgrounds that reproduce the correct conformal anomaly. For such backgrounds the calculation of the Wilson line in the adiabatic approximation indicates only a Coulomb repulsion.
It is suggested \cite{CDTT} that current cosmic acceleration arises due to modification of General Relativity by the terms with negative powers of curvature. We show that time-dependent (hyperbolic) compactifications of string/M-theory lead to the effective 4d gravity which naturally contains such terms. The same may be achieved in braneworld by the proper choice of the boundary action. Hence, such a model which seems to eliminate the need for dark energy may have the origin in M-theory.
The modified gravity, which eliminates the need for dark energy and which seems to be stable, is considered. The terms with positive powers of the curvature support the inflationary epoch while the terms with negative powers of the curvature serve as effective dark energy, supporting current cosmic acceleration. The equivalent scalar-tensor gravity may be compatible with the simplest solar system experiments.
Some cosmological implications of ultraviolet quantum effects leading to a condensation of Born-Infeld matter are considered. It is shown that under very general conditions the quantum condensate can not act as phantom matter if its energy density is positive. On the other hand, it behaves as an effective cosmological constant in the limit where quantum induced contributions to the energy-momentum tensor dominate over the classical effects.
We discuss the model consisting of tachyon which may have the negative kinetic energy plus scalar phantom and plus conformal quantum matter. It is demonstrated that such a model naturally admits two deSitter phases where the early universe inflation is produced by quantum effects and the late time accelerating universe is caused by phantom/tachyon. The energy conditions bounds for such cosmology are derived. It is interesting that effective equation of state may change its sign which depends from the proper choice of the combination of phantom/tachyon and quantum effects.
The role of quantum effects in brane-world cosmology is investigated. It is shown in time-independent formulation that quantum creation of deSitter branes in five-dimensional (A)dS bulk occurs with also account of brane quantum CFT contribution. The surface action is chosen to include cosmological constant and curvature term. (The time-dependent formulation of quantum-corrected brane FRW equations is shown to be convenient for comparison with Supernovae data). The particles creation on deSitter brane is estimated and is shown to be increased due to KK modes. The deSitter brane effective potential due to bulk quantum matter on 5d AdS space is found. It may be used to get the observable cosmological constant in the minimum of the potential (stabilization). The appearence of the entropy bounds from bulk field equation is also mentioned.
We consider deSitter universe and Nariai universe induced by quantum CFT with classical phantom matter and perfect fluid. The model represents the combination of trace-anomaly driven inflation and phantom driven deSitter universe. The similarity of phantom matter with quantum CFT indicates that phantom scalar may be the effective description for some quantum field theory. It is demonstrated that it is easier to achieve the acceleration of the scale factor preserving the energy conditions in such unified model. Some properties of unified theory (anti-gravitating solutions, negative ADM mass Nariai solution, relation with steady state) are briefly mentioned.
Five-dimensional braneworld cosmology with deSitter (inflationary) brane universe induced by classical and quantum matter is discussed. It is shown that negative energy phantom field with quantum CFT supports the creation of deSitter universe. On the same time, pure phantom or dust with quantum effects, or Chaplygin gas with quantum effects may naturally lead to the occurence of Anti-deSitter brane universe but not deSitter one. It is also interesting that unlike to four-dimensional gravity, for phantom with (or without) quantum contribution the standard cosmological energy conditions may be effectively satisfied.
The bulk gauge fields on 5d AdS black hole are discussed. We construct the bulk (and the corresponding brane) gauge propagator when black hole has large radius. The properties of gauge and ghost propagators are studied in both, minkowski or euclidean signature. In euclidean formulation the propagator structure corresponds to the one of theory at finite temperature (which depends on coordinates). The decoupling of KK modes and localization of gauge fields on flat brane is demonstrated. We show that with such a bulk there is no natural solution of hierarchy problem.
Thermodynamics of 5d SdS black hole is considered. Thermal fluctuations define the (sub-dominant) logarithmic corrections to black hole entropy and then to Cardy-Verlinde formula and to FRW brane cosmology. We demonstrate that logarithmic terms (which play the role of effective cosmological constant) change the behavior of 4d spherical brane in dS, SdS or Nariai bulk. In particularly, bounce Universe occurs or 4d dS brane expands to its maximum and then shrinks. The entropy bounds are also modified by next-to-leading terms. Out of braneworld context the logarithmic terms may suggest slight modification of standard FRW cosmology.
We discuss the bulk Casimir effect (effective potential) for a conformal or massive scalar when the bulk represents five-dimensional AdS or dS space with two or one four-dimensional dS brane, which may correspond to our universe. Using zeta-regularization, the interesting conclusion is reached, that for both bulks in the one-brane limit the effective potential corresponding to the massive or to the conformal scalar is zero. The radion potential in the presence of quantum corrections is found. It is demonstrated that both the dS and the AdS braneworlds may be stabilized by using the Casimir force only. A brief study indicates that bulk quantum effects are relevant for brane cosmology, because they do deform the de Sitter brane. They may also provide a natural mechanism yielding a decrease of the four-dimensional cosmological constant on the physical brane of the two-brane configuration.
We calculate the holographic conformal anomaly and brane Newton potential when bulk is 5d AdS BH. It is shown that such anomaly is the same as in the case of pure AdS or (asymptotically) dS bulk spaces, i.e. it is (bulk) metric independent one. While Newton potential on the static brane in AdS BH is different from the one in pure AdS space, the gravity trapping still occurs for two branes system. This indicates to metric independence of gravity localization.
Exact calculations are given for the Casimir energy for various fields in $R\times S^3$ geometry. The Green's function method naturally gives a result in a form convenient in the high-temperature limit, while the statistical mechanical approach gives a form appropriate for low temperatures. The equivalence of these two representations is demonstrated. Some discrepancies with previous work are noted. In no case, even for ${\cal N}=4$ SUSY, is the ratio of entropy to energy found to be bounded.
Using graviton correlator on deSitter (dS) brane in 5d AdS or dS bulk we calculate the four-dimensional Newton potential. For flat brane in AdS bulk the Randall-Sundrum result is recovered. For flat brane in dS bulk the sign of subleading ($1/r^3$) term in Newton potential is negative if compare with AdS bulk. In accordance with dS/CFT correspondence this indicates that dual CFT should be non-unitary (for example, higher derivative conformal theory).