skip to main content


Title: Neutrino energy transport in weak decoupling and big bang nucleosynthesis

In this study, we calculate the evolution of the early universe through the epochs of weak decoupling, weak freeze-out and big bang nucleosynthesis (BBN) by simultaneously coupling a full strong, electromagnetic, and weak nuclear reaction network with a multienergy group Boltzmann neutrino energy transport scheme. The modular structure of our code provides the ability to dissect the relative contributions of each process responsible for evolving the dynamics of the early universe in the absence of neutrino flavor oscillations. Such an approach allows a detailed accounting of the evolution of the νe, ν¯e, νμ, ν¯μ, ντ, ν¯τ energy distribution functions alongside and self-consistently with the nuclear reactions and entropy/heat generation and flow between the neutrino and photon/electron/positron/baryon plasma components. This calculation reveals nonlinear feedback in the time evolution of neutrino distribution functions and plasma thermodynamic conditions (e.g., electron-positron pair densities), with implications for the phasing between scale factor and plasma temperature; the neutron-to-proton ratio; light-element abundance histories; and the cosmological parameter Neff. We find that our approach of following the time development of neutrino spectral distortions and concomitant entropy production and extraction from the plasma results in changes in the computed value of the BBN deuterium yield. For example, for particularmore » implementations of quantum corrections in plasma thermodynamics, our calculations show a 0.4% increase in deuterium. These changes are potentially significant in the context of anticipated improvements in observational and nuclear physics uncertainties.« less
 [1] ;  [2] ;  [3] ;  [4] ;  [5]
  1. Univ. of California, San Diego, La Jolla, CA (United States); Univ. of Michigan, Ann Arbor, MI (United States)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  3. Univ. of California, San Diego, La Jolla, CA (United States); Univ. of San Diego, San Diego, CA (United States)
  4. Univ. of California, San Diego, La Jolla, CA (United States)
  5. Univ. of California, San Diego, La Jolla, CA (United States); North Carolina State Univ., Raleigh, NC (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 2470-0010
Grant/Contract Number:
AC52-06NA25396; 257842
Accepted Manuscript
Journal Name:
Physical Review D
Additional Journal Information:
Journal Volume: 93; Journal Issue: 8; Journal ID: ISSN 2470-0010
American Physical Society (APS)
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Laboratory Directed Research and Development (LDRD) Program
Country of Publication:
United States
74 ATOMIC AND MOLECULAR PHYSICS; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; Atomic and Nuclear Physics; Astronomy and Astrophysics
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1249651