Speaker
Description
The synthesis of carbon and oxygen plays a central role in nuclear astrophysics, as the reactions 3α → ¹²C + γ and ¹²C(α,γ)¹⁶O govern the stellar C/O ratio and influence stellar evolution and nucleosynthesis. Despite their importance, a consistent theoretical description of these processes at low energies remains challenging due to strong Coulomb effects. In this talk, I present a near-zero-range Effective Field Theory (EFT) approach tailored to α-cluster systems, exploiting the separation of scales between the internal excitation of the α particle and the low-energy dynamics of cluster degrees of freedom. Two-body α–α interactions are constructed up to next-to-next-to-leading order and constrained by low-energy scattering data and the properties of the ⁸Be resonance. Three- and four-body contact interactions are then introduced to reproduce the bound and excited states of ¹²C and ¹⁶O. Within this framework, preliminary results are shown for the triple-α capture process as well as for the radiative capture reaction ¹²C(α,γ)¹⁶O. Calculated cross sections, reaction rates, and low-energy astrophysical S factors are discussed and compared with available experimental data and existing theoretical approaches. Ongoing developments aim at improving the quantitative accuracy of the method and at providing a unified EFT description of carbon and oxygen production in stellar environments.