Theoretical developments in nuclear astrophysics

We discuss the main reactions encountered in nuclear astrophysics, and espe cially reactions between light nuclei such as those involved in the CNO cyc le or in He burning. A general presentation of the different types of react ions is illustrated by some examples. We develop more specifically the pote ntial and R-matrix: models, often used in the literature, and we apply them to some typical reactions. Other direct or indirect methods are briefly pr esented. Finally we discuss the calculation of reaction rates.