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Inflationary Scenarios from String Theory

Inflationary Scenarios from String Theory. F. Quevedo Cambridge COSMO 2005. MOTIVATION. Inflation: very successful but only scenarios in search of a theory String theory: fundamental theory but lacks experimental tests. Is it possible to `derive’ inflation from string theory?. HISTORY.

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Inflationary Scenarios from String Theory

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  1. Inflationary Scenarios from String Theory F. Quevedo Cambridge COSMO 2005

  2. MOTIVATION • Inflation: very successful but only scenarios in search of a theory • String theory: fundamental theory but lacks experimental tests. • Is it possible to `derive’ inflation from string theory?

  3. HISTORY • t<1986 Calabi-Yau String Compactifications: Many free moduli (size and shape of extra dimensions) from gmn, Bmn, φ, AmI • 1986<t<1991 Geometric moduli: candidate for inflaton fields. But no potentials (V=0). Or V too steep: Candelas et al. Dilaton S, Kähler T Complex structure U Wilson lines W Binetruy-Gaillard, Banks et al Brustein-Steinhardt

  4. t=1998 More moduli! : D-brane inflation. But V=0 or non-calculable. t=2001 Brane/Antibrane inflation: Dvali-Tye Burgess et al., Dvali et al Generically no slow roll, but…

  5. End of inflation: Open string tachyon Burgess et al. V tachyon Y Tachyon complex topological defects D (p-2) branes cosmic strings ! Sen, Burgess et al. Tye et al. Copeland et al.

  6. Intersecting Brane Inflation Garcia-Bellido et al. Y: Inflaton End of inflation: tachyon Also: D3-D7 inflation Kallosh et al.

  7. Outstanding Problem • Moduli Stabilization A Solution: turn-on fluxes t> 2003 KKLT Scenario …GKP, KKLT, …

  8. KKLT Scenario …GKP, KKLT, … • Type IIB String on Calabi-Yau orientifold • Turn on Fluxes ∫aF3 = n a ∫bH3 = m b SuperpotentialW = ∫ G3ΛΩ, G3 = F3 –iSH3 Scalar Potential: V= eK |DaW|2 Minimum DaW = 0 Fixes Ua and S T moduli unfixed: No-Scale models Size of cycle a = Ua GKP

  9. To fix Kähler moduli: Non-perturbative D7 effects Non-perturbative Fluxes Volume SUSY AdS minimum (W0 << 1)

  10. Lifting to de Sitter (add anti D3 branes, D-terms, etc.) KKLT, BKQ, SS SUSY breaking term V axion volume

  11. The Landscape • Huge number of discrete vacua >10500 • Statistics • Randall-Sundrum warping from strings! • Non SUSY de Sitter • Dark energy? • `SM’ on D3/D7branes • Soft SUSY breaking? • Inflation? AD, DD, DDF, GKTT,CQ,BGHLW GKP BP CG-MQU

  12. Realistic Models CG-MQU, CSU

  13. Exponentially Large Volumes BBCQ, CQS • At least two Kähler moduli (h21>h11>1) • Perturbative corrections to K Example : Exponentially large !

  14. Non SUSY AdS W0~1-10 String scale: Ms2=Mp2/V

  15. KKLT AdS Non SUSY AdS Both minima merge W0~10-10 W0<10-11

  16. Inflation and Moduli Stabilization

  17. Brane-Antibrane Inflation KKLMMT, HKP, KTW, FT, BCSQ, … φ inflaton field D3 Brane φ

  18. Slow-roll (large field) inflation possible. Need 1/1000 fine tuning of parameters to get 60-efoldings (η-problem) N~60, δH~10-5 for Ms~ 1015 GeV ns~1.05 Burgess, Cline, Stoica, FQ Needs at least two throats ! Kallosh et al. Also: D3-D7 on K3xT2 DBI in the sky Silverstein-Tong, Chen

  19. Warped Tachyonic Inflation Sen, Raeymakers, Cremades-Sinha-FQ A,B depend on warping (fluxes) and E&M fields on non-BPS brane. If A,B~1 no slow-roll AB large slow-roll No fine-tuning! But need large fluxes

  20. INITIAL CONDITIONS Sen’s open string completeness conjecture t -t Pre big-bang ! ? Inflation and compactification or big-crunch/bang and decompactification ! ?

  21. Racetrack Inflation Blanco-Pillado et al. Topological eternal inflation ! Slow roll if 1/1000 fine tuning, N~60, δH~10-5 for Ms~1015 GeV ns~ 0.95

  22. Improved Racetrack Blanco-Pillado et al. Douglas et al. Explicitly derived model Similar physics

  23. Kähler Moduli Inflation Conlon-FQ Any Calabi-Yau: h21>h11>2 V Large field inflation No fine-tuning!! 0.960<n<0.967 τn volume

  24. CONCLUSIONS • Exciting times • Type IIB: Several inflationary scenarios, Inflaton: Kahler modulus, brane sparation, tachyon, Wilson lines , Complex structure moduli (?). • Reheating • Extensions to other string theories (Becker et al) • Initial conditions • Overshooting problem,…. Open questions

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