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Trispectrum versus bispectrum in single-field inflation

Engel, Kevin T. and Lee, Keith S. M. and Wise, Mark B. (2009) Trispectrum versus bispectrum in single-field inflation. Physical Review D, 79 (10). p. 103530. ISSN 2470-0010.

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In the standard slow-roll inflationary cosmology, quantum fluctuations in a single field, the inflaton, generate approximately Gaussian primordial density perturbations. At present, the bispectrum and trispectrum of the density perturbations have not been observed and the probability distribution for these perturbations is consistent with Gaussianity. However, Planck satellite data will bring a new level of precision to bear on this issue, and it is possible that evidence for non-Gaussian effects in the primordial distribution will be discovered. One possibility is that a trispectrum will be observed without evidence for a nonzero bispectrum. It is not difficult for this to occur in inflationary models where quantum fluctuations in a field other than the inflaton contribute to the density perturbations. A natural question to ask is whether such an observation would rule out the standard scenarios. We explore this issue and find that it is possible to construct single-field models in which inflaton-generated primordial density perturbations have an observable trispectrum, but a bispectrum that is too small to be observed by the Planck satellite. However, an awkward fine-tuning seems to be unavoidable.

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Additional Information:© 2009 The American Physical Society. Received 23 January 2009; published 28 May 2009; publisher error corrected 16 June 2009. We thank Gary Shiu for correspondence regarding Ref. [32]. This work was supported in part by the U.S. Department of Energy (DOE) under the cooperative research agreement No. DE-FG02-92ER40701. K. L. was also supported by the Sherman Fairchild Foundation. PACS numbers: 98.80.Cq.
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Department of EnergyDE-FG02-92ER40701
Sherman Fairchild FoundationUNSPECIFIED
Issue or Number:10
Record Number:CaltechAUTHORS:20090813-132038823
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:15014
Deposited By: Tony Diaz
Deposited On:13 Aug 2009 22:07
Last Modified:03 Oct 2019 00:54

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