Abstract

We consider the possibility of enhancing the inflationary tensor mode by introducing a spectator scalar field with a small sound speed which induces gravitational waves as a second-order effect. We analytically obtain the power spectra of gravitational waves and curvature perturbation induced by the spectator scalar field. We find that the small sound speed amplifies the curvature perturbation much more than the tensor mode and the current observational constraint forces the induced gravitational waves to be negligible compared with those from the vacuum fluctuation during inflation.

Details

Title
Can a spectator scalar field enhance inflationary tensor mode?
Author
Fujita, Tomohiro 1 ; Jun’ichi Yokoyama 2 ; Yokoyama, Shuichiro 3 

 Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), WPI, TODIAS, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, 277-8583, Japan; Department of Physics, Graduate School of Science, The University of Tokyo, Bunkyo-ku 113-0033, Japan 
 Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), WPI, TODIAS, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, 277-8583, Japan; Research Center for the Early Universe (RESCEU), Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan 
 Department of Physics, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima, Tokyo, 171-8501, Japan 
Publication year
2015
Publication date
Apr 2015
Publisher
Oxford University Press
e-ISSN
20503911
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
3171471108
Copyright
© The Author(s) 2015. Published by Oxford University Press on behalf of the Physical Society of Japan. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.