Non-Gaussianities in Multi-field Inflation TeX Export

@misc{citeulike:894345, abstract = {We compute the amplitude of the non-Gaussianities in inflationary models with multiple, uncoupled scalar fields. This calculation thus applies to all models of assisted inflation, including N-flation, where inflation is driven by multiple axion fields arising from shift symmetries in a flux stabilized string vacuum. The non-Gaussianities are associated with nonlinear evolution of the field (and density) perturbations, characterized by the parameter \$f\_{NL}\$. We derive a general expression for the nonlinear parameter, incorporating the evolution of perturbations after horizon-crossing. This is valid for arbitrary separable potentials during slow roll. To develop an intuitive understanding of this system and to demonstrate the applicability of the formalism we examine several cases with quadratic potentials: two-field models with a wide range of mass ratios, and a general N-field model with a narrow mass spectrum. We uncover that \$f\_{NL}\$ is suppressed as the number of e-foldings grows, and that this suppression is increased in models with a broad spectrum of masses. On the other hand, we find no enhancement to \$f\_{NL}\$ that increases with the number of fields. We thus conclude that the production of a large non-Gaussian signal in multi-field models of inflation is thus very unlikely. Finally, we compute a spectrum for the scalar spectral index that incorporates the nonlinear corrections to the fields' evolution.}, archivePrefix = {arXiv}, author = {Battefeld, Thorsten and Easther, Richard}, citeulike-article-id = {894345}, citeulike-linkout-0 = {http://arxiv.org/abs/astro-ph/0610296}, citeulike-linkout-1 = {http://arxiv.org/pdf/astro-ph/0610296}, day = {11}, eprint = {astro-ph/0610296}, keywords = {inflation, multifield, nongaussianities, toread}, month = {Oct}, posted-at = {2006-10-12 16:53:23}, priority = {3}, title = {Non-Gaussianities in Multi-field Inflation}, url = {http://arxiv.org/abs/astro-ph/0610296}, year = {2006} }

TY - ELEC ID - citeulike:894345 L3 - citeulike-article-id:894345 N2 - We compute the amplitude of the non-Gaussianities in inflationary models with multiple, uncoupled scalar fields. This calculation thus applies to all models of assisted inflation, including N-flation, where inflation is driven by multiple axion fields arising from shift symmetries in a flux stabilized string vacuum. The non-Gaussianities are associated with nonlinear evolution of the field (and density) perturbations, characterized by the parameter $f_{NL}$. We derive a general expression for the nonlinear parameter, incorporating the evolution of perturbations after horizon-crossing. This is valid for arbitrary separable potentials during slow roll. To develop an intuitive understanding of this system and to demonstrate the applicability of the formalism we examine several cases with quadratic potentials: two-field models with a wide range of mass ratios, and a general N-field model with a narrow mass spectrum. We uncover that $f_{NL}$ is suppressed as the number of e-foldings grows, and that this suppression is increased in models with a broad spectrum of masses. On the other hand, we find no enhancement to $f_{NL}$ that increases with the number of fields. We thus conclude that the production of a large non-Gaussian signal in multi-field models of inflation is thus very unlikely. Finally, we compute a spectrum for the scalar spectral index that incorporates the nonlinear corrections to the fields' evolution. TI - Non-Gaussianities in Multi-field Inflation KW - inflation KW - multifield KW - nongaussianities KW - toread AU - Battefeld, Thorsten AU - Easther, Richard PY - 2006/Oct/11/ UR - http://arxiv.org/abs/astro-ph/0610296 ER -