International Journal of Modern Physics A

We review our recent proposal for a background-independent formulation of a holographic theory of quantum gravity. The present paper incorporates the necessary background material on geometry of canonical quantum theory, holography and space–time thermodynamics, Matrix theory, as well as our specific proposal for a dynamical theory of geometric quantum mechanics, as applied to Matrix theory. At the heart of this review is a new analysis of the conceptual problem of time and the closely related and phenomenologically relevant problem of vacuum energy in quantum gravity. We also present a discussion of some observational implications of this new viewpoint on the problem of vacuum energy.

Using an analytical approach, the sensitivity to sin² 2θ₁₃ with infinite statistics in a spectral analysis is investigated in reactor neutrino oscillation experiments with one reactor and two identical detectors. We derive an useful formula for the sensitivity which depends only on two parameters (the uncorrelated bin-to-bin systematic error over the square-root of the number of bins) and σ_dB (the bin-to-bin correlated detector specific systematic error) if they are smaller than other errors. It is pointed out that the spectrum analysis is advantageous over the rate analysis in search of neutrino oscillations for .

In this paper we review the properties of the black hole entropy in the light of a general conformal field theory treatment. We find that the properties of horizons of the BTZ black holes in ADS₃, can be described in terms of an effective unitary CFT₂ with central charge c = 1 realized in terms of the Fubini–Veneziano vertex operators. It is found a relationship between the topological properties of the black hole solution and the infinite algebra extension of the conformal group in 2D, SU(2, 2), i.e. the Virasoro algebra, and its subgroup SL(2, Z) which generates the modular symmetry. Such a symmetry induces a duality for the black hole solution with angular momentum J ≠ 0. On the light of such a global symmetry we reanalyze the Cardy formula for CFT₂ and its possible generalization to D>2 proposed by E. Verlinde.

The presence of boundaries modifies the modes of quantum fields, which may in turn modifies the spontaneous excitation rate of accelerated atoms in interaction with these fields. In this paper, we study the effect of the presence of a reflecting boundary on the spontaneous excitation of a uniformly accelerated polarized multilevel atom interacting with quantum scalar fields in a dipole-derivative coupling scheme. We separately calculate the contributions of modified vacuum fluctuations and the radiation reaction to the spontaneous excitation rate of the atom. Our results show that the presence of the boundary modulates the excitation rate and makes it a function of the atom's distance from the boundary. When the atom is placed closer and closer to the boundary, the influence of the boundary becomes more and more drastic, with the contribution of the atom's polarization in the direction parallel to the boundary to the spontaneous excitation rate dramatically suppressed while that in the normal direction greatly enhanced.

We probe the existence of supersymmetric vacua of the type IIB orientifold of the elliptic Calabi–Yau space P₁₁₁₆₉[18] where generically two complex structure moduli z_i, the dilaton τ and the two Kähler moduli T_i are stabilized by fluxes and gaugino condensates. The usual KKLT procedure, which integrates out the complex structure moduli and the dilaton, actually has to be modified, such that one keeps the dependence on τ. We derive explicitly the resulting effective superpotential W_eff(τ) for the dilaton for various flux combinations. As this is actually a nonholomorphic quantity one must properly work with the G-function. The remaining SUSY equations for τ and the T_i can be resolved explicitly.

We obtain limits on the electromagnetic and weak dipole moments of the tau-lepton in the framework of a left–right symmetric model (LRSM) and a class of E₆ inspired models with an additional neutral vector boson Z_θ. Using as an input the data obtained by the L3 and OPAL collaborations for the reaction e⁺e^- → τ⁺τ^-γ, we get a stringent limit on the LRSM mixing angle ϕ, -1.66 × 10^-3 < ϕ<1.22×10^-3, which in turn induces bounds on the tau weak dipole moments which are consistent with the bounds obtained recently by the DELPHI and ALEPH collaborations from the reaction e⁺e^-→τ⁺τ^-. We also get similar bounds for the weak dipole moments of the tau lepton in the framework of E₆ superstring models.