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D-Brane as a Model for COSMOLOGICAL DARK ENERGY

D-Brane as a Model for COSMOLOGICAL DARK ENERGY. I . A ref'eva Steklov Mathematical Institute , Moscow. XLI-th Rencontres de Moriond Contents and Structures of the Universe, La Thuile, 19-25 March, 2006. DE State Parameter from WMAP3. + 0.07

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D-Brane as a Model for COSMOLOGICAL DARK ENERGY

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  1. D-Brane as a Model for COSMOLOGICAL DARK ENERGY I. Aref'eva Steklov Mathematical Institute, Moscow XLI-th Rencontres de Moriond Contents and Structures of the Universe, La Thuile, 19-25 March, 2006

  2. DEState Parameter from WMAP3 + 0.07 - 0.09 WMAP+SNLS: w=- 0.97 WMAP+large-scale structure+SNLS, no k=0 assumption: w = -1.06 + 0.13 - 0.08

  3. Theoretical proposals: w>-1 : “Quintessence” w=-1: Cosmological Constant w<-1: “Phantom” For all: small value of the energy density (small value of thecosmological constant)

  4. Phenomenological DE Models with w < -1 “Big Rip” or Doomsday 1) Fluid with w<-1 Caldwell, Kamionkowski, Weinberg, PRL 2003 2) Ghost scalar field (Phantom): no “Big Rip” violation of energy conditions, violation of unitarity, instability But:

  5. DE Models with w < -1 from Fundamental Principles (from string theory) Universe is a brane embedded in a higher dim. bulk space-time Brane Cosmology:

  6. I.A., Koshelev, S.Vernov, Phys.Lett.B,2005; Phys.Rev.D,2005 I.A., L.Joukovkaya, JHEP,2005. I.A. astro-ph/0410443 This talk: w<-1 Universe from string field theory Universe as slowly decaying D3-brane An effective phantom behavior After the decay : stable spectrum

  7. D-brane String Field Theory Boson SFT: Witten, 1986 Cubic Superstring SFT: I.A.,Medvedev,Zubarev; Preitschopf, Thorn,Yost, 1990 A.Sen and B.Zwiebach, 2000 Tachyon in GSO(-) SFT D-brane decay

  8. E=-1/4 SFT action for NSR tachyons Kostelecky, Samuel, 1988; N.Berkovits, A.Sen, B.Zwiebach, 2000 I.A., D.Belov, A.Koshelev, P.Medvedev, 2001 K.Ohmouri, 2003 Sen’s conjecture: T=1/4

  9. NSR SFT tachyon + Gravity New conjecture: Effective cosmological constant

  10. E.O.M. for String Field Tachyon in FRW metric Infinite number of derivatives

  11. Effective local approximation Ghost Why we get a change of sign? Solution: (kink) numerically Flat case I.A,Joukovskaya,Koshelev,JHEP,2002

  12. Exact Solution for Toy Model I.A.,Koshelev,S.Vernov, PRD,2005

  13. Hubble Parameter

  14. Hubble Parameter SUMMARY: Universe as D3-brane String Field Theory Dynamics Dark Energy as Open String Tachyon It includes a small cosmological constant + small correction from a scalar field. Nonlocal String Scalar Field Dynamics: w<-1

  15. D-BRANE !

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