# Does the CMB prefer a leptonic Universe?

Schwarz D, Stuke M (2013)
New Journal of Physics 15(3).

Journal Article | Published | English

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Abstract
Recent observations of the cosmic microwave background at smallest angular scales and updated abundances of primordial elements indicate an increase of the energy density and the helium-4 abundance with respect to standard big bang nucleosynthesis with three neutrino flavour. This calls for a reanalysis of the observational bounds on neutrino chemical potentials, which encode the number asymmetry between cosmic neutrinos and anti-neutrinos and thus measures the lepton asymmetry of the Universe. We compare recent data with a big bang nucleosynthesis code, assuming neutrino flavour equilibration via neutrino oscillations before the onset of big bang nucleosynthesis. We find a preference for negative neutrino chemical potentials, which would imply an excess of anti-neutrinos and thus a negative lepton number of the Universe. This lepton asymmetry could exceed the baryon asymmetry by orders of magnitude.
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Schwarz D, Stuke M. Does the CMB prefer a leptonic Universe? New Journal of Physics. 2013;15(3).
Schwarz, D., & Stuke, M. (2013). Does the CMB prefer a leptonic Universe? New Journal of Physics, 15(3).
Schwarz, D., and Stuke, M. (2013). Does the CMB prefer a leptonic Universe? New Journal of Physics 15.
Schwarz, D., & Stuke, M., 2013. Does the CMB prefer a leptonic Universe? New Journal of Physics, 15(3).
D. Schwarz and M. Stuke, “Does the CMB prefer a leptonic Universe?”, New Journal of Physics, vol. 15, 2013.
Schwarz, D., Stuke, M.: Does the CMB prefer a leptonic Universe? New Journal of Physics. 15, (2013).
Schwarz, Dominik, and Stuke, Maik. “Does the CMB prefer a leptonic Universe?”. New Journal of Physics 15.3 (2013).
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arXiv 1211.6721

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