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Revisiting the Constraint on the Helium Abundance from CMB

Kazuhide Ichikawa·Tomo Takahashi
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Abstract

We revisit the constraint on the primordial helium mass fraction Yp from observations of cosmic microwave background (CMB) alone. By minimizing chi square of recent CMB experiments over 6 other cosmological parameters, we obtained rather weak constraints as 0.17 < Yp < 0.52 at 1 sigma C.L. for a particular data set. We also study the future constraint on cosmological parameters when we take account of the prediction of the standard big bang nucleosynthesis (BBN) theory as a prior on the helium mass fraction where Yp can be fixed for a given energy density of baryon. We discuss the implications of the prediction of the standard BBN on the analysis of CMB.

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Kazuhide Ichikawa, Tomo Takahashi. 2006-04-05. Revisiting the Constraint on the Helium Abundance from CMB. https://doi.org/10.1103/physrevd.73.063528

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