Sculpting the extra dimensions: inflation from codimension-2 brane back-reaction

Journal Article · Sun Apr 01 04:00:00 EDT 2012 · Journal of Cosmology and Astroparticle Physics

DOI:https://doi.org/10.1088/1475-7516/2012/04/037· OSTI ID:22279780

Nierop, Leo van

We construct an inflationary model in 6D supergravity that is based on explicit time-dependent solutions to the full higher-dimensional field equations, back-reacting to the presence of a 4D inflaton rolling on a space-filling codimension-2 source brane. Fluxes in the bulk stabilize all moduli except the 'breathing' modulus (that is generically present in higher-dimensional supergravities). Back-reaction to the inflaton roll causes the 4D Einstein-frame on-brane geometry to expand, a(t)∝t{sup p}, as well as exciting the breathing mode and causing the two off-brane dimensions to expand, r(t)∝t{sup q}. The model evades the general no-go theorems precluding 4D de Sitter solutions, since adjustments to the brane-localized inflaton potential allow the power p to be dialed to be arbitrarily large, with the 4D geometry becoming de Sitter in the limit p → ∞ (in which case q = 0). Slow-roll solutions give accelerated expansion with p large but finite, and q = ½. Because the extra dimensions expand during inflation, the present-day 6D gravity scale can be much smaller than it was when primordial fluctuations were generated — potentially allowing TeV gravity now to be consistent with the much higher gravity scale required at horizon-exit for observable primordial gravity waves. Because p >> q, the 4 on-brane dimensions expand more quickly than the 2 off-brane ones, providing a framework for understanding why the observed four dimensions are presently so much larger than the internal two. If uplifted to a 10D framework with 4 dimensions stabilized, the 6D evolution described here could describe how two of the six extra dimensions evolve to become much larger than the others, as a consequence of the enormous expansion of the 4 large dimensions we can see.

• OSTI ID: 22279780
• Journal Information: Journal of Cosmology and Astroparticle Physics, Journal Name: Journal of Cosmology and Astroparticle Physics Journal Issue: 04 Vol. 2012; ISSN 1475-7516
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ASTROPHYSICS
COSMOLOGY
DE SITTER GROUP
DE SITTER SPACE
EXPANSION
FIELD EQUATIONS
FLUCTUATIONS
GRAVITATION
GRAVITATIONAL WAVES
MANY-DIMENSIONAL CALCULATIONS
MATHEMATICAL SOLUTIONS
POTENTIALS
SUPERGRAVITY
TEV RANGE
TIME DEPENDENCE