Non-Gaussianities in General Single Field Inflation Xingang Chen CTP, MIT astro-ph/0507053; hep-th/0605045, with Minxin Huang, Shamit Kachru, Gary Shiu; astro-ph/0611645, with Eugene Lim, Richard Easther; and in progres with Rachel Bean, Henry Tye, Jiajun Xu, in preparation. 陈陈陈
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Non-Gaussianities in General Single Field Inflation Xingang Chen CTP, MIT astro-ph/0507053; hep-th/0605045, with Minxin Huang, Shamit Kachru, Gary Shiu;
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Non-Gaussianities inGeneral Single Field Inflation
Xingang Chen
CTP, MIT
astro-ph/0507053;hep-th/0605045, with Minxin Huang, Shamit Kachru, Gary Shiu;astro-ph/0611645, with Eugene Lim, Richard Easther; and in progress;with Rachel Bean, Henry Tye, Jiajun Xu, in preparation.
陈新刚
Inflation Models and Observations
• Inflation mechanisms and models
Slow-roll inflation --- using flat potential; DBI inflation --- using speed-limit in warped space; K-inflation --- inflation driven by kinetic energy.
• WMAP measurement on CMBR
Spectral index:
Running of spectral index: Tensor to scalar ratio: Non-Gaussianity:
Most General Non-Gaussianities in Single Field Theory
• Motivations
Null hypothesis on specific models; Fit or constrain parameters model-independently;
Several string models has distinctive predictions on non-Gaussianities;
Straightforward evaluation of non-Gaussianities for future models in this general class.
• Single field inflation:
Inflaton is responsible for density perturbations;
Lagrangian is arbitrary function of and ;
Arbitrary sound speed and (to be defined).
• Review of several classes of models
• General formalism
• General form of non-Gaussianities
• Using non-G to probe new physics
Outline
Review of Several Classes of Models
1. Slow-roll inflation (Linde 82; Albrecht & Steinhardt 82)
Generate branes as candidate inflatons Exit B-throat, roll through bulk, settle down in another throat Enough warping: DBI inflation; Flat potential: slow-roll inflation.
• Branes are moving ultra-relativistically
For example, in IR DBI,
Lorentz factor,
In DBI inflation, potential energy dominates,despite the fact that inflatons are ultra-relativistic.
• Pressure and Energy
3. K-inflation
• Lagrangian
For example,
• Attractor solution
• Inflation driven by kinetic energy if
• Can use a hybrid field to end the inflation
• Not realized in string theory so far
(Armendariz-Picon, Damour, Mukhanov, 99)
• Review of several classes of models
• General formalism
• General form of non-Gaussianities
• Using non-G to probe new physics
Outline
A General Formalism (Garriga & Mukhanov, 99)
• Slow variation parameters
• More general than the usual slow-roll parameters
Flat potential v.s. steep potential (DBI) or no potential (k-inflation) Non-relativistic slow-roll v.s. ultra-relativistic fast-roll