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Cosmology Now and Tomorrow

Cosmology Now and Tomorrow. Misao Sasaki (YITP, Kyoto University). KASI-YITP Joint-Workshop: Cosmology Now and Tomorrow 17 -18 Feb 2012. Cosmology Now and Tomorrow. Misao Sasaki (YITP, Kyoto University). KASI-YITP Joint-Workshop: Cosmology Now and Tomorrow 17 -18 Feb 2012.

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Cosmology Now and Tomorrow

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  1. Cosmology Now and Tomorrow Misao Sasaki (YITP, Kyoto University) KASI-YITP Joint-Workshop: Cosmology Now and Tomorrow 17 -18 Feb 2012

  2. Cosmology Now and Tomorrow Misao Sasaki (YITP, Kyoto University) KASI-YITP Joint-Workshop: Cosmology Now and Tomorrow 17 -18 Feb 2012 Theoretical

  3. Cosmology Now and Tomorrow Misao Sasaki (YITP, Kyoto University) KASI-YITP Joint-Workshop: Cosmology Now and Tomorrow 17 -18 Feb 2012 Theoretical – personal, biased perspective –

  4. current status • big bang theory has been firmly established CMB spectrum at T=2.725K • strong evidence for inflation only to be confirmed (by tensor modes?) • “standard model” parameters: WMAP 7yr

  5. current and future issues I. GR cosmology • perturbation theory • numerical cosmology I do NOT touch Dark Energy/Modified Gravity recent developments in MG → R Kimura II. Inflation • multi-field, non-canonical/minimal • conformal frame (in-)dependence III. String Theory Landscape • observational signatures?

  6. I. GR Cosmology • perturbation theory linear theory has been extremely successful over the past 20-30 years quantization and evolution of perturbations from inflation single-field slow-roll inflation Mukhanov ’85, MS ’86,... Lyth-Liddle ’92, Stewart-Lyth ‘93

  7. CMB anisotropy Sunyaev & Zeldovich ’70, .... SW Doppler conformal distance to Last Scattering Surface WMAP 7yr growth of density perturbations (>~ 10 Mpc) Peebles ’80, ..., Wang & Steinhardt ‘98

  8. E only a few papers, a lot to be done • need for NL theory is growing Non-gaussianity from inflation testing/constraining models of inflation 2nd and higher order perturbation theory → JC Hwang higher order effects in CMB spectrum no systematic studies, need to be developed Naruko et al. in progress (NL) GR effects on cosmological observables Meures & Bruni ‘11, Jeong, Schmidt & Hirata ’11,...

  9. “vacuum” practically nothing has been done yet inhomogeneous universe models • Numerical GR Cosmology testing TLB (anti-Copernican) model quantifying GR effects in LSS formation ....... perturbative? Post Newtonian? BH universe BH dominated (“vacuum”) universe → CM Yoo (primordial) BH formation Shibata & MS ’99, ...(but spherically sym) 2D & 3D codes to be developed

  10. II. Inflation • multi-field/non-canonical/non-minimal models • PLANCK will announce the first result by Feb 2013, exactly 1 year from now. So be prepared ! • construct as many models as possible which are compatible with current WMAP data, and which can be tested by PLANCK etc. (not too distant future) spectral index, tensor perturbation, non-Gaussianity, ad-iso correlation, primordial BH,... → Alabidi, Saito, Stewart, Yamaguchi any other new signatures?

  11. Makino & MS ‘91, ... , Gong, Hwang, Park, MS & Song ‘11 • Linear theory • conformal (in-)dependence of cosmological perturbations tensor-type perturbation Definition of hijis apparently W-independent.

  12. vector-type perturbation Definitions of Bjand Hjare asloW-independent. tensor & vector perturbations are conformal frame-independent

  13. scalar-type perturbation Definitions of B and E are W-independent. But AandRare W-dependent!

  14. Nevertheless,... • The important, curvature perturbation Rc , conserved on superhorizon scales, is defined on comoving hypersurfaces. uniform f (df = 0) frame-independent if W=W(f) • For scalar-tensor theory with we have Rc=Rdf=0 is W-independent! generalization to nonlinear case is straightforward

  15. isocurvature y • multi-component case general case is discussed in Gong et al. (’11) • Is distinction between adiabatic and isocurvature perturbations conformally invariant? Yes, if we consider trajectories in field space, because it is coordinate-independent. f But this assumes reduction of phase space to field space: The assumption seems violated in general, eg, when different comps have different curvature couplings. → Minamitsuji & White, in progress

  16. III. String theory landscape 16 16 Lerche, Lust & Schellekens (’87), Bousso & Pochinski (’00), Susskind, Douglas, KKLT (’03), ... • There are ~ 10500 vacua in string theory • vacuum energy rv may be positive or negative • typical energy scale ~ MP4 • some of them have rv <<MP4 which ?

  17. Is there any way to know what kind of landscape we live in? Or at least to know what kind of neighborhood we live in?

  18. distribution function in flux space Vacua with enhanced gauge symmetry by courtesy of T. Eguchi may explain the origin of gauge symmetry (SU(3)xSU(2)xU(1)) in our Universe

  19. de Sitter (dS) & Anti-de Sitter (AdS) • dS space: rv>0, O(4,1) symmetry • AdS space: rv<0, O(3,2) symmetry collapses within t~1/H

  20. 0 20 • A universe jumps around in the landscape by quantum tunneling • it can go up to a vacuum with larger rv ( dS space ~ thermal state with T =H/2p ) • if it tunnels to a vacuum with negative rv , it collapses within t ~ MP/|rv|1/2. • so we may focus on vacua with positive rv: dS vacua rv Sato, MS, Kodama & Maeda (’81)

  21. 21 • Anthropic landscape • Not all of dS vacua are habitable. “anthropic” landscape Susskind (‘03) • A universe jumps around in the landscape and settles down to a final vacuum with rv,f ~ MP2H02 ~(10-3eV)4. rv,f must notbe larger than this value in order to account for the formation of stars and galaxies. • Just before it has arrived the final vacuum (=present universe), it must have gone through an era of (slow-roll) inflation and reheating, to create “matter and radiation.” rvac → rmatter ~ T4: birth of Hot Bigbang Universe

  22. Most plausible state of the universe before inflation is a dS vacuum with rv ~ MP4. dS = O(4,1) O(5) ~ S4 false vacuum decay via O(4) symmetric (CDL) instanton Coleman & De Luccia (‘80) O(4) O(3,1) inside bubble is an open universe bubble wall false vacuum

  23. creation of open universe open (hyperbolic) space bubble wall analytic continuation

  24. 24 • Natural outcome would be a universe with W0 <<1. • “empty” universe: no matter, no life • Anthropic principle suggests that # of e-folds of inflation inside the bubble (N=HDt) should be ~ 50 – 60 : just enough to make the universe habitable. Garriga, Tanaka & Vilenkin (‘98), Freivogel et al. (‘04) • Observational data excluded open universe with W0 <1. • Nevertheless, the universe may be slightly open: may be tested by PLANCK+BAO Colombo et al. (‘09)

  25. What if 1-W0 is actually confirmed to be non-zero:~10-2 -10-3? revisit open inflation! see if we can say anything about Landscape effect of tunneling on large angular scale CMB Yamauchi, Linde, Naruko, MS & Tanaka ’11

  26. other possible signatures CMB cold/hot spots = bubble collision? Aguirre & Johnson ’09, Kleban, Levi & Sigurdson ’11,... Non-Gaussianity from bubbles? Blanco-Pillado & Salem ’10, Sugimura et al. in progress Tunneling probability / resonant tunneling? Tye & Wohns ’09, Brown & Dahlen ‘11 Measure problem? Garriga & Vilenkin ‘08, Freivogel ’11, Vilenkin ’11, .... any others?

  27. Summary • develop GR cosmology further: perturbative, non-perturbative, numerical, observational... (GR can be replace by MG) • propose testable inflation models non-minimal, non-canonical, multi-field, .... • look for signatures of string theory landscape ................ ! ... ?

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