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Limits on Neutrino-Neutrino Scattering in the Early Universe

Cyr-Racine, Francis-Yan and Sigurdson, Kris (2014) Limits on Neutrino-Neutrino Scattering in the Early Universe. Physical Review D, 90 (12). Art. No. 123533. ISSN 1550-7998. doi:10.1103/PhysRevD.90.123533.

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In the standard model neutrinos are assumed to have streamed across the Universe since they last scattered when the standard-model plasma temperature was ∼MeV. The shear stress of free-streaming neutrinos imprints itself gravitationally on the cosmic microwave background (CMB) and makes the CMB a sensitive probe of neutrino scattering. Yet, the presence of nonstandard physics in the neutrino sector may alter this standard chronology and delay neutrino free streaming until a much later epoch. We use observations of the CMB to constrain the strength of neutrino self interactions G_(eff) and put limits on new physics in the neutrino sector from the early Universe. Within the context of conventional Λ CDM parameters cosmological data are compatible with G_(eff)≲1/(56  MeV)^2 and neutrino free streaming might be delayed until their temperature has cooled to as low as ∼25  eV. Intriguingly, we also find an alternative cosmology compatible with cosmological data in which neutrinos scatter off each other until z∼10^4 with a preferred interaction strength in a narrow region around G_(eff)≃1/(10  MeV)^2≃8.6×10^8G_F, where G_F is the Fermi constant. This distinct self-interacting neutrino cosmology is characterized by somewhat lower values of both the scalar spectral index and the amplitude of primordial fluctuations. While we phrase our discussion here in terms of a specific scenario, our constraints on the neutrino visibility function are very general.

Item Type:Article
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URLURL TypeDescription Paper
Cyr-Racine, Francis-Yan0000-0002-7939-2988
Sigurdson, Kris0000-0002-6729-0765
Additional Information:© 2014 American Physical Society. Received 15 June 2013; revised manuscript received 2 December 2014; published 29 December 2014. We thank Roland de Putter and Olivier Doré for useful discussions. The work of F. Y. C. R. was performed in part at the California Institute of Technology for the Keck Institute for Space Studies, which is funded by the W. M. Keck Foundation. The research of K. S. is supported in part by a National Science and Engineering Research Council (NSERC) of Canada Discovery grant. We thank the Kavli Institute for Theoretical Physics, where part of this work was completed, for its hospitality. This research was supported in part by the National Science Foundation under Grant No. NSF PHY11-25915. Part of the research described in this paper was carried out at the Jet Pro- pulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration
Group:Keck Institute for Space Studies
Funding AgencyGrant Number
W. M. Keck FoundationUNSPECIFIED
National Science and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Keck Institute for Space Studies (KISS)UNSPECIFIED
Issue or Number:12
Classification Code:PACS: 98.80.Cq, 14.60.St, 98.70.Vc
Record Number:CaltechAUTHORS:20130624-101741754
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Official Citation:Limits on neutrino-neutrino scattering in the early Universe Francis-Yan Cyr-Racine and Kris Sigurdson Phys. Rev. D 90, 123533 (2014) – Published 29 December 2014
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:39048
Deposited By: Ruth Sustaita
Deposited On:24 Jun 2013 17:43
Last Modified:09 Nov 2021 23:42

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