Browsing by Author "Berglund, Per"
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- Dark energy and string theoryBerglund, Per; Hübsch, Tristan; Minic, Djordje (2019-11-10)A radiatively stable de Sitter spacetime is constructed by considering an intrinsically non-commutative and generalized-geometric formulation of string theory, which is related to a family of F-theory models endowed with non-trivial anisotropic axion-dilaton backgrounds. In particular, the curvature of the canonically conjugate dual space provides for a positive cosmological constant to leading order, that satisfies a radiatively stable see-saw-like formula, which in turn induces the dark energy in the observed spacetime. We also comment on the non-commutative phase of the non-perturbative formulations of string theory/quantum gravity implied by this approach.
- Relating the cosmological constant and supersymmetry breaking in warped compactifications of IIB string theoryBerglund, Per; Hubsch, T.; Minic, Djordje (American Physical Society, 2003-02-15)It has been suggested that the observed value of the cosmological constant is related to the supersymmetry breaking scale M-susy through the formula Lambdasimilar toM(p)(4)(M-susy/M-p)(8). We point out that a similar relation naturally arises in the codimension two solutions of warped spacetime varying compactifications of string theory, in which nonisotropic stringy moduli induce a small but positive cosmological constant.
- String Theory Bounds on the Cosmological Constant, the Higgs Mass, and the Quark and Lepton MassesBerglund, Per; Hübsch, Tristan; Minic, Djordje (MDPI, 2023-08-28)In this paper, we elaborate on the new understanding of the cosmological constant and the gauge hierarchy problems in the context of string theory in its metastring formulation, based on the concepts of modular spacetime and Born geometry. The interplay of phase space (and Born geometry), the Bekenstein bound, the mixing between ultraviolet (UV) and infrared (IR) physics and modular invariance in string theory is emphasized. This new viewpoint is fundamentally rooted in quantum contextuality and not in statistical observer bias (anthropic principle). We also discuss the extension of this point of view to the problem of masses of quarks and leptons and their respective mixing matrices.
- Stringy Bubbles Solve de Sitter TroublesBerglund, Per; Hübsch, Tristan; Minic, Djordje (MDPI, 2021-09-28)Finding four-dimensional de Sitter spacetime solutions in string theory has been a vexing quest ever since the discovery of the accelerating expansion of the universe. Building on a recent analysis of bubble-nucleation in the decay of (false-vacuum) AdS backgrounds where the interfacing bubbles themselves exhibit a de Sitter geometry we show that this resonates strongly with a stringy cosmic brane construction that naturally provides for an exponential mass-hierarchy and the localization of both gravity and matter, in addition to an exponentially suppressed positive cosmological constant. Finally, we argue that these scenarios can be realized in terms of a generalization of a small resolution of a conifold singularity in the context of a (Lorentzian) Calabi–Yau 5-fold, where the isolated (Lorentzian) two complex dimensional Fano variety is a four-dimensional de Sitter spacetime.