High-Precision Measurement of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="normal">D</mi><mo stretchy="false">(</mo><mi>γ</mi><mo>,</mo><mi>n</mi><mo stretchy="false">)</mo><mi>p</mi></mrow></math> Photodisintegration Reaction and Implications for Big Bang Nucleosynthesis

Y. J. Chen; Z. R. Hao; J. J. He; T. Kajino; S.-I. Ando; Y. Luo; H. R. Feng; L. Y. Zhang; G. T. Fan; H. W. Wang; H. Zhang; Z. L. Shen; L. X. Liu; H. H. Xu; Y. Zhang; P. Jiao; X. Y. Li; Y. X. Yang; S. Jin; K. J. Chen; W. Q. Shen; Y. G. Ma

doi:10.1103/tbbt-s819

High-Precision Measurement of $D (γ, n) p$ Photodisintegration Reaction and Implications for Big Bang Nucleosynthesis

Y. J. Chen ¹, Z. R. Hao², J. J. He ^1,*, T. Kajino ^3,4,5,†, S.-I. Ando ^6,7, Y. Luo ⁸, H. R. Feng ³, L. Y. Zhang ⁹, G. T. Fan^2,‡ et al.

H. W. Wang², H. Zhang ¹, Z. L. Shen⁹, L. X. Liu ², H. H. Xu ², Y. Zhang², P. Jiao², X. Y. Li¹, Y. X. Yang ², S. Jin¹⁰, K. J. Chen¹⁰, W. Q. Shen², and Y. G. Ma ^1,11,12,§

¹Key Laboratory of Nuclear Physics and Ion-beam Application (MoE), Institute of Modern Physics, Fudan University, Shanghai 200433, China
²Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, China
³School of Physics, Peng Huanwu Collaborative Center for Research and Education, and International Research Center for Big-Bang Cosmology and Element Genesis, Beihang University, Beijing 100191, China
⁴Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-033, Japan
⁵Division of Science, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
⁶Department of Physics Education, Daegu University, Gyeongsan, Gyeongbuk 38453, Korea
⁷Department of Display and Semiconductor Engineering, Research Center for Nano-Bio Science, Sunmoon University, Asan, Chungnam 31460, Korea
⁸School of Physics, Peking University, and Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, China
⁹College of Physics and Astronomy, Beijing Normal University, Beijing 100875, China
¹⁰Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
¹¹Shanghai Research Center for Theoretical Nuclear Physics, NSFC and Fudan University, Shanghai 200438, China
¹²School of Physics, East China Normal University, Shanghai 200062, China

^*Contact author: hejianjun@fudan.edu.cn
^†Contact author: kajino@buaa.edu.cn
^‡Contact author: fangongtao@zjlab.org.cn
^§Contact author: mayugang@fudan.edu.cn

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Phys. Rev. Lett. 136, 052701 – Published 4 February, 2026

DOI: https://doi.org/10.1103/tbbt-s819

Abstract

We report on a high-precision measurement of the $D (γ, n) p$ photodisintegration reaction at the newly commissioned Shanghai Laser Electron Gamma Source, employing a quasimonochromatic $γ$ -ray beam from Laser Compton Scattering. The cross sections were determined over $E_{γ} = 2.327 - 7.089 MeV$ , achieving up to a factor of 2.2 improvement in precision near the neutron separation threshold. Combined with previous data in a global Markov chain Monte Carlo analysis using dibaryon effective field theory, we obtained the unprecedentedly precise $p (n, γ) D$ cross sections and thermonuclear rate, with a precision up to $\approx 4$ times higher than previous evaluations. Implemented in a standard Big Bang nucleosynthesis framework, this new rate decreases uncertainty of the key cosmological parameter of baryon density $Ω_{b} h^{2}$ by up to $\approx 16 %$ relative to the Laboratory for Underground Nuclear Astrophysics (LUNA) result. A residual $\approx 1.2 σ$ tension between $Ω_{b} h^{2}$ constrained from primordial $D / H$ observations and cosmic microwave background measurements persists, highlighting the need for improved $d d$ reaction rates and offering potential hints of new physics beyond the standard model of cosmology.

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High-Precision Measurement of $D (γ, n) p$ Photodisintegration Reaction and Implications for Big Bang Nucleosynthesis