Curvature and isocurvature perturbations from twofield inflation in a slowroll expansion

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Curvature and isocurvature perturbations from
two-field inflation in a slow-roll expansion
Christian Byrnes Portsmouth University Supervisor
David Wands 8th June, 2006
Byrnes and Wands, astro-ph/0605679
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Motivation
SUSY/ string theory predict the existence of many
scalar fields Focus on the case of two scalar
fields

• Allows new observational possibilities
• Isocurvature perturbations
• Cross correlation
• Different consistency relations

• Including next-to-leading order terms shows new
  behaviour
• Generically the adiabatic and isocurvature
  perturbations are correlated at Hubble-exit
• In some models the second order contribution to
  the tilt dominates

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Review of single field inflation
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Two field inflation The background trajectory is
no longer unique
Adiabatic/curvature perturbation, Entropy/isocurva
ture perturbation, The two types of perturbation
can be correlated
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(No Transcript)
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Gordon et al., astro-ph/0009131
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CB and Wands, astro-ph/0605679
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The tilts including second order corrections
CB and Wands, astro-ph/0605679
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Specific inflation models Curvature
perturbations from broken symmetries Primordial
curvature perturbation is generated from the
symmetry breaking parameter during preheating
Kolb, Riotto and Vallinotto, astro-ph/0410546
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Are the power spectra well approximated by power
laws?
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Gravitational Waves
Stewart and Lyth, gr-qc/9602019
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Consistency relations
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Curvaton scenario
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Conclusions

• In two field inflation there is a much greater
  range of possible behaviour
• Including next-to-leading order correction terms
  in slow roll shows that the adiabatic and
  isocurvature perturbations are correlated at
  Hubble-exit
• In some inflationary models the leading
  contribution to the tilt is from second order
  terms
• is not well approximated by a power law
  if
• There are consistency relations in two field
  inflation