Nflation: observational predictions from the random matrix mass spectrum SAK and Andrew R. Liddle 76 Phys. Rev. D 76, , 2007, arXiv:

 Introduction  Nflation Basic set-up Multi-field dynamics  Observational predictions  Numerical results The spectral index  Summary Outline

Single field (large) Chaotic inflation Multiple fields Assisted inflation from particle physics in inflation models N f Large number of fields( N f ) Nflation S.Dimopoulos et al, hep-th/ P. Kanti and K. A. Olive, 60 Phys. Rev. D60, (1999), 464 Phys. Lett. B464, 192 (1999). N. Kaloper and A. R. Liddle, 61 Phys, Rev, D61, , (2000). Random initial conditions Different mass spectrum Adiabatic perturbations Random initial conditions Different mass spectrum Adiabatic perturbations Density perturbations The tensor-to-scalar ratio Density perturbations The tensor-to-scalar ratio Introduction 58 A.R. Liddle, A. Mazumdar, and F. E. Schunck, Phys. Rev. D58, (R). Initial condition problem

 The definition A set of massive uncoupled scalar fields with a particular mass spectrum  Potentials Periodic potentials (cosine ones)  quadratic ones Near to the minima of their own potentials  Mass spectrum by the random matrix  Random initial conditions With the field initial conditions  i /M Pl chosen uniformly in the range [0,1]  Symmetry to [-1,1] Nflation Ⅰ S. Dimopoulos et al, hep-th/ R. Easther and L. McAllister, JCAP 0605, 018 (2006). 74 SAK and Andrew R. Liddle, Phys. Rev. D74, (2006).

 Multi-field dynamics The total potential Field equations  The number of e-foldings Nflation Ⅱ

 Multi-field dynamics The total potential Field equations Slow-roll approximations  The number of e-foldings Nflation Ⅱ

 The perturbation spectrum of the curvature perturbations  The tensor-to-scalar ratio independent N f independent of N f, of their masses, and of their initial conditions Observational predictions Ⅰ D. H. Lyth and A. Riotto, Phys. Rep. 314, 1 (1999), R. Easther and L. McAllister, JCAP 0605, 018 (2006) L. Alabidi and D.H. Lyth, JCAP 0605, 016 (2006). 95 M. Sasaki and E. D. Stewart, Prog.Theor.Phys. 95, 71 (1996). ~0.16 (N=50)

 The non-gaussianity parameter independent also independent of model parameters Observational predictions Ⅱ 0509 D. Seery and J. E. Lidsey, JCAP 0509, 011 (2005), 71 D.H. Lyth and Y. Rodriguez, Phys. Rev. D.71, (2005). 74 SAK and Andrew R. Liddle, Phys. Rev. D74, (2006). ~O(0.01) (N=50)

 The spectral index always less than n S =0.96, the single field case Observational predictions Ⅲ 95 M. Sasaki and E. D. Stewart, Prog. Theor. Phys. 95, 71 (1995). 74 Y-S. Piao, Phys. Rev. D74, (2006).

N f  The relations between the total number of e-foldings N total and the number of fields N f N total  N f /12 indicate more than 600 fields needed to get enough e-foldings, i.e. more than 50 e-foldings Numerical results 74 SAK and Andrew R. Liddle, Phys. Rev. D74, (2006).

TThe mass spectrum by the random matrix  m i 2 (  ) T he average mass term m=10 -6 M pl  =0, 0.3, 0.5, 0.9 TThe spectral index  =0, 0.1, 0.3, 0.5, 0.7, 0.8, 0.9, 0.95 The spectral index NfNfNfNf Observational Lower Limit (WMAP3) nSnS i m i 2 /M Pl 2 R. Easther and L. McAllister, 0605 JCAP 0605, 018 (2006). 76 SAK and Andrew R. Liddle, Phys. Rev. D 76, (2007). Observational Lower Limit (WMAP5)

 At least 600 fields needed  The tensor-to-scalar ratio & the non-gaussianity parameter independent Completely independent of the model parameters N f N f and the mass spectrum independent Also independent of the field initial conditions Summary Ⅰ

 The spectral index Depends Depends on the model parameters; N f n S ( N f, m i ) depends Also depends on the initial conditions independent Existence of the independent regime for the initial conditions ‘thermodynamic’ called ‘thermodynamic’ regime independent Provided  < 0.5, becomes independent N f independent With a large N f, n S also becomes independent Summary Ⅱ Thank you!