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This content will become publicly available on October 4, 2017

Title: Neutrino flavor transformation in the lepton-asymmetric universe

We investigate neutrino flavor transformation in the early Universe in the presence of a lepton asymmetry, focusing on a two-flavor system with 1–3 mixing parameters. We identify five distinct regimes that emerge in an approximate treatment neglecting collisions as the initial lepton asymmetry at high temperature is varied from values comparable to current constraints on the lepton number down to values at which the neutrino-neutrino forward-scattering potential is negligible. The characteristic phenomena occurring in these regimes are (1) large synchronized oscillations, (2) minimal flavor transformation, (3) asymmetric (ν- or ν¯-only) MSW, (4) partial MSW, and (5) symmetric MSW. We examine our numerical results in the framework of adiabaticity, and we illustrate how they are modified by collisional damping. Lastly, we point out the existence of matter-neutrino resonances in the early Universe and show that they suffer from nonadiabaticity.
Authors:
 [1] ;  [2] ;  [3] ;  [3] ;  [4]
  1. Univ. of California, San Diego, La Jolla, CA (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Univ. of Torino, Torino (Italy)
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  4. Univ. of California, San Diego, La Jolla, CA (United States)
Publication Date:
OSTI Identifier:
1329909
Report Number(s):
LA-UR--16-25128
Journal ID: ISSN 2470-0010; PRVDAQ
Grant/Contract Number:
AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Physical Review D
Additional Journal Information:
Journal Volume: 94; Journal Issue: 8; Journal ID: ISSN 2470-0010
Publisher:
American Physical Society (APS)
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS astronomy and astrophysics