New paper on D(p,γ)3He is out!

A paper entitled "The baryon density of the Universe from an improved rate of deuterium burning" has been published on Nature.

The abundance of deuterium produced soon after the Big Bang carries precious information about the amount of ordinary matter and radiation permeating the Universe in its infancy.

In our study, we report on a new evaluation of the baryon density based on Big Bang Nucleosynthesis (BBN), now in much better agreement with that derived by PLANCK from the relic Cosmic Microwave Background. We further place constraints on the amount of dark radiation, with broad implications for the standard cosmological model. Our findings were obtained by exploiting the negligible cosmic-ray background deep underground at LUNA.

We bombarded a high-purity deuterium gas target with an intense proton beam from the LUNA 400-kV accelerator and detected the γ rays from the D(p,γ)3He nuclear reaction with a high-purity germanium detector. Our experimental results settle the most uncertain nuclear physics input to BBN calculations and substantially improve the reliability of using primordial abundances as probes of the physics of the early Universe.

S factor of the D(p,γ)3He reaction; the new LUNA results (filled red circles) indicate a significant improvement in the accuracy of the S factor compared to previous data sets. The best fit (red solid line) obtained in this work is entirely dominated by the LUNA data.

Likelihood distribution of the baryon density (lower x-axis) and baryon-to-photon ratio (upper x-axis). The red curve shows the distribution of the baryon density obtained using the new LUNA S factor for the predicted deuterium abundance.

The INFN press release is available here.

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