BRANEWORLD COSMOLOGICAL PERTURBATIONS

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BRANEWORLD COSMOLOGICAL PERTURBATIONS

• COSMOLOGY AS A PROBE OF QUANTUM GRAVITY?

Roy Maartens
Tokyo RESCEU November 2003
University of Portsmouth
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why brane-worlds?

• GR breaks down
• need quantum gravity in the early universe

• no QG theory as yet
• but M theory is a promising candidate

• key aspect is branes
• large extra dimensions
• lower Planck scale

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GR phenomenology QG

• standard cosmology highly successful (Peiris)
• but still a paradigm seeking a theory
• inflation? dark energy? (dark matter?)
• quantum modifications to GR
• better understanding (inflation)
• solve puzzles
• (dark energy, low quadrupole?,...)
• new features
• slow progress in M theory cosmology
• use braneworld phenomenology

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• 2 key aspects
• braneworld gravity brings new features
• moduli (Kofman talk), cyclic universe (Khoury),
• AdS/CFT and holography (Tanaka),
• bulk inflation (Soda),
• precision cosmology can constrain
  braneworld models (and M Theory?)
• via dynamics BBN, (Langlois)
• via large-scale structure

(future) via gravity waves
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- low energy approximation

• structure formation - very low energy
• bulk curvature scale lt 1mm ltlt branes
• use gradient expansion to solve
• need 2 boundary
• conditions

Kanno-Soda02 Shiromizu-Koyama02 Rhodes-vdBruck-B
rax-Davis03
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scalar perturbations
Koyama03
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brane-world CMB anisotropies

• model with most simple background
• radion fixed
• no dark radiation

Koyamas poster
Koyama03
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some future work

• RS model OK so far
• compute CMB for
• more realistic background
• one-brane model
• models with bulk dilaton
• models with quantum corrections
• M theory models?
• compute GW spectrum
• in high-energy radiation
• models with bulk dilaton
• models with quantum corrections
• M theory models?

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