Modern Physics Letters A

A ℛ "dual" transform is introduced which relates Quantum Field Theory and String regimes, both in a curved background with D-non-compact dimensions. This operation maps the characteristic length of one regime into the other (and, as a consequence, mass domains as well). The ℛ-transform is not an assumed or a priori imposed symmetry but is revealed by the QFT and String dynamics in curved backgrounds. The Hawking–Gibbons temperature and the string maximal or critical temperature are ℛ-mapped one into the other. If back reaction of quantum matter is included, Quantum Field Theory and String phases appear, and ℛ-relations between them manifest as well. These ℛ-transformations are explicitly shown in two relevant examples: Black Hole and de Sitter spacetimes.

We discuss a framework to analyze the transmission of supersymmetry breaking in models of intersecting D-branes. Generically, different intersections preserve different fractions of an extended bulk supersymmetry, thus breaking supersymmetry completely but in a nonlocal way. We analyze this mechanism in a 5D toy model where two brane intersections, which are separated in the fifth dimension, break different halves of an extended supersymmetry. The sector of the theory on one brane intersection feels the breakdown of the residual supersymmetry only through two-loop interactions involving a coupling to fields from the other intersection. We compute the diagrams that contribute to scalar masses on one intersection and find that the masses are proportional to the compactification scale up to logarithmic corrections. We also compute the three-loop diagrams relevant to the Casimir energy between the two intersections and find a repulsive Casimir force.

We report on a new two-parameter class of cosmological solutions of the Einstein–Maxwell equations. The solutions have everywhere regular curvature invariants. We prove that the solutions are geodesically complete and globally hyperbolic.

It is shown that the quantum potential may be used in the form of an equation of state together with the equation of hydrostatic equilibrium to obtain quantum-gravitational bodies, which are polytropes of index 2 in the Newtonian case and geons of Planck mass and radius in relativistic case.

In an earlier paper, Alvarez, Alvarez-Gaumé, Barbón and Lozano pointed out, that the only way to "flatten" negative curvature by means of a T-duality is by introducing an appropriate, non-constant NS–NS two-form B. In this paper, we are investigating this further and ask, whether it is possible to T-dualize AdS_d space to flat space with some suitably chosen B. To answer this question, we derive a relationship between the original curvature tensor and the one of the T-dualized metric involving the B-field. It turns out that there is one component which is independent of B. By inspection of this component, we show that it is not possible to dualize AdS_d to flat space irrespective of the choice of B. Finally, we examine the extension of AdS to an AdS₅ × S⁵ geometry and propose a chain of S- and T-dualities together with an SL(2, ℤ) coordinate transformation, leading to a dual D9-brane geometry.

A novel method for the exact solvability of quantum systems is discussed and used to obtain closed analytical expressions in arbitrary dimensions for the exact solutions of the hydrogenic atom in the external potential ΔV(r) = br + cr², which is based on the recently introduced supersymmetric perturbation theory.

We present a whole frame for the cosmic strings, inflation and dark energy with the complex scalar field which can be regarded as the order parameter of our universe. One can find that the comic strings emerge in the zeros of the complex scalar field in the early universe. And with the evolution of complex scalar field, inflation and dark energy can be understood in this frame.

Based on recently proposed unified models for dark matter and energy which are constructed by introducing a generalized Chaplygin vacuum fluid, we suggest in this paper a new scenario for quintessential inflation which does not rely on the existence of a specific potential for the vacuum field, but on a generalization of the definition of the Hilbert–Einstein action for a massless scalar field conformally-coupled to gravity that contains an extra Lagrangian term for the generalized vacuum Chaplygin fluid and the corresponding new surface term.