The Physics Society of Iran Iranian Journal of Physics Research 1682-6957 25 4 2026 02 20 A semi-analytical approach to the abundance of light elements in Big Bang nucleosynthesis A semi-analytical approach to the abundance of light elements in Big Bang nucleosynthesis 391 404 3746 10.47176/ijpr.25.4.42095 FA Seyyed Mohammad Shahrokhi Department of Physics, Lorestan University, Khorramabad Ahmad Mohamadnejad Department of Physics, Lorestan University, Khorramabad 0000-0002-9695-1999 Journal Article 2025 04 27 This paper presents a comprehensive semi-analytical approach to the temporal evolution and final abundance of light elements 7Be<strong> </strong> formed during Big Bang nucleosynthesis. By systematically examining the fundamental processes, we reveal the complex physics involved in the formation of these primordial elements. Our findings not only enhance the understanding of nucleosynthesis dynamics but also provide valuable insights into the conditions of the early universe and emphasize the importance of light elements in cosmic evolution. One of the most significant results of this paper is the derivation of semi-analytical relations for the final abundance of light elements as a function of the normalized baryon-to-photon ratio (η_10). In the end, the acceptable range of the parameter  η_10 is discussed<strong> </strong>through a<strong> </strong>comparison of observational results. This paper presents a comprehensive semi-analytical approach to the temporal evolution and final abundance of light elements 7Be<strong> </strong> formed during Big Bang nucleosynthesis. By systematically examining the fundamental processes, we reveal the complex physics involved in the formation of these primordial elements. Our findings not only enhance the understanding of nucleosynthesis dynamics but also provide valuable insights into the conditions of the early universe and emphasize the importance of light elements in cosmic evolution. One of the most significant results of this paper is the derivation of semi-analytical relations for the final abundance of light elements as a function of the normalized baryon-to-photon ratio (η_10). In the end, the acceptable range of the parameter  η_10 is discussed<strong> </strong>through a<strong> </strong>comparison of observational results. https://ijpr.iut.ac.ir/article_3746_e8542a04d734d0cae36d648b3f519e5c.pdf