1 / 24

The Curvature Perturbation from Vector Fields: the Vector Curvaton Case

The Curvature Perturbation from Vector Fields: the Vector Curvaton Case. Mindaugas Karčiauskas. Dimopoulos, Kar č iauskas, Lyth, Rodriguez, JCAP 13 (2009) Kar č iauskas, Dimopoulos, Lyth, PRD 80 (2009) Dimopoulos, Kar č iauskas, Wagstaff, arXiv:0907.1838

alexia
Download Presentation

The Curvature Perturbation from Vector Fields: the Vector Curvaton Case

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Curvature Perturbation from Vector Fields: the Vector Curvaton Case Mindaugas Karčiauskas Dimopoulos, Karčiauskas, Lyth, Rodriguez, JCAP 13 (2009) Karčiauskas, Dimopoulos, Lyth, PRD 80 (2009) Dimopoulos, Karčiauskas, Wagstaff, arXiv:0907.1838 Dimopoulos, Karčiauskas, Wagstaff, arXiv:0909.0475

  2. Density perturbations • Primordial curvature perturbation – a unique window to the early Universe; • Origin of structure <= quantum fluctuations; • Scalar fields - the simplest case; • Whyvector fields: • Theoretical side: • No fundamental scalar field has been discovered; • The possible contribution from gauge fields is neglected; • Observational side: • Axis of Evil: alignment of 2-4-8-16 spherical harmonics of CMB; • Large cold spot, radio galaxy void; Land & Magueijo (2005)

  3. The Vector Curvaton Scenario The energy momentum tensor ( ): Inflationscale invariant spectrum Light Vector Field Heavy Vector Fieldvector field oscillationsPreasureless isotropicmatter: Vector Field Decay.onset of the Hot Big Bang Dimopoulos (2006)

  4. Parity conser-ving theories: Vector Field Perturbations • Massive => 3 degrees of vector field freedom; • The power spectra • The anisotropy parameters of particle production :

  5. Vector Field Perturbations From observations, statistically anisotropic contribution <30%. Groeneboom & Eriksen (2009) Statistically isotropic Statistically anisotropic

  6. The Curvature Perturbation • The total curvature perturbation • The curvature perturbation (δN formula) , where • The anisotropic power spectrum of the curvature perturbation: • For vector field perturbations • The non-Gaussianity • Current observational constraints: • Expected from Plank if no detection: Groeneboom & Eriksen (2009) Pullen & Kamionkowski (2007)

  7. 1. Anisotropic 2. Modulation is not subdominant 3. 4. Same preferred direction. 5. Configuration dependent modulation. Non-Minimal Vector Curvaton • Scale invariance => • The vector field power spectra: • The anisotropy in the power spectrum: • Non-Gaussianity: =>

  8. At the end of inflation: and . Scale invariance: 1. 2. 2nd case: Small coupling => can be a gauge field; Richest phenomenology; Varying Kinetic Function See Jacques’ talk on Wednesday

  9. At the end of inflation Light vector field Heavy vector field Isotropic particle production Anisotropic particle production

  10. The anisotropy in the power spectrum: The non-Gaussianity: The parameter space & The Anisotropic Case, 1. Anisotropic 2. Modulation is notsubdominant 3. 4. Same preferred direction 5. Configuration dependent modulation

  11. No scalar fields needed! Standard predictions of the curvaton mechanism: The parameter space: The Isotropic Case,

  12. Vector fieldscan affect or even generate the curvature perturbation; If anisotropic particle production ( ): If isotropic particle => no need for production scalar fields Two examples: 1. 2. Conclusions 1. Anisotropic and . 2. Modulation is not subdominant 3. , where 4. Same preferred direction . 5. Configuration dependent modulation.

  13. Dimopoulos, Karčiauskas, Lyth, Rodriguez, JCAP 13 (2009) Karčiauskas, Dimopoulos, Lyth, PRD 80 (2009) Dimopoulos, Karčiauskas, Wagstaff, arXiv:0907.1838 Dimopoulos, Karčiauskas, Wagstaff, arXiv:0909.0475

  14. Anisotropy Parameters Anisotropy in the particle production of the vector field: Statistical anisotropy in the curvature perturbation:

  15. Random Fields with Statistical Anisotropy Isotropic - preferred direction

  16. Present Observational Constrains • The power spectrum of the curvature perturbation: & almost scale invariant; • Non-Gaussianity from WMAP5 (Komatsu et. al. (2008)):

  17. δN formalism • To calculate we use formalism (Sasaki, Stewart (1996); Lyth, Malik, Sasaki (2005)); • Recently in was generalized to include vector field perturbations (Dimopoulos, Lyth, Rodriguez (2008)): where , , etc.

  18. Estimation of   • For subdominant contribution can be estimated on a fairly general grounds; • All calculations were done in the limit • Assuming that one can show that

  19. Difficulties with Vector Fields Excessive large scale anisotropy The energy momentum tensor ( ): No particle production Massless U(1) vector fields are conformally invariant

  20. Avoiding excessive anisotropy Orthogonal triad of vector fields Ford (1989) Large number of identical vector fields Golovnev, Mukhanov, Vanchurin (2008) Modulation of scalar field dynamicsYokoyama, Soda (2008) Vector curvaton;Dimopoulos (2006)

  21. Particle Production Massless U(1) vector no particlefield is conformally => production; invariant A known problem in primordial magneticfields literature; Braking conformal invariance: Add a potential, e.g. Modify kinetic term, e.g.

  22. Stability of the Model • Two suspected instabilities for longitudinal mode: 1. Ghost; 2. Horizon crossing; 3. Zero mass; • Ghost: • Only for subhorizon modes: • Initially no particles & weak coupling; • Horizon crossing: • Exact solution: • Independent constants:

More Related