Fine-tuning with Brane-Localized Flux in 6D Supergravity

Abstract

There are claims in the literature that the cosmological constant problem could be solved in a braneworld model with two large (micron-sized) supersymmetric extra dimensions. The mechanism relies on two basic ingredients: First, the cosmological constant only curves the compact bulk geometry into a rugby shape while the 4D curvature stays flat. Second, a brane-localized flux term is introduced in order to circumvent Weinberg's fine-tuning argument, which otherwise enters here through a backdoor via the flux quantization condition. In this paper, we show that the latter mechanism does not work in the way it was designed: The only localized flux coupling that guarantees a flat on-brane geometry is one which preserves the scale invariance of the bulk theory. Consequently, Weinberg's argument applies, making a fine-tuning necessary again. The only remaining window of opportunity lies within scale invariance breaking brane couplings, for which the tuning could be avoided. Whether the corresponding 4D curvature could be kept under control and in agreement with the observed value will be answered in our companion paper [arXiv:1512.03800].

16 pages

References in corpus (10)

• Beyond the Cosmological Standard Model
• Tests of the Gravitational Inverse-Square Law below the Dark-Energy Length Scale
• Sidestepping the Cosmological Constant with Football-Shaped Extra Dimensions
• Large Dimensions and Small Curvatures from Supersymmetric Brane Back-reaction
• EFT for Vortices with Dilaton-dependent Localized Flux
• A Problem With delta-functions: Stress-Energy Constraints on Bulk-Brane Matching (with comments on arXiv:1508.01124)
• Distributed SUSY Breaking: Dark Energy, Newton's Law and the LHC
• Brane induced gravity: Ghosts and naturalness
• The Gravity of Dark Vortices: Effective Field Theory for Branes and Strings Carrying Localized Flux
• Self-Tuning at Large (Distances): 4D Description of Runaway Dilaton Capture

Cited by in corpus (8)

• Point-Particle Effective Field Theory I: Classical Renormalization and the Inverse-Square Potential
• Gravitational Mechanisms to Self-Tune the Cosmological Constant: Obstructions and Ways Forward
• Point-Particle Effective Field Theory III: Relativistic Fermions and the Dirac Equation
• A Problem With delta-functions: Stress-Energy Constraints on Bulk-Brane Matching (with comments on arXiv:1508.01124)
• Generalised scalar-tensor theories and self-tuning
• SLED Phenomenology: Curvature vs. Volume
• Self-Tuning at Large (Distances): 4D Description of Runaway Dilaton Capture
• Rotating kinky braneworlds