Cartan Connections Associated to a $\beta$-Conformal Change in Finsler Geometry

On a Finsler manifold $(M,L)$, we consider the change $L\longrightarrow\bar{L}(x,y)=e^{\sigma(x)}L(x,y)+\beta (x,y)$, which we call a $\beta$-conformal change. This change generalizes various types of changes in Finsler geometry: conformal, $C$-conformal, $h$-conformal, Randers and generalized Randers changes. Under this change, we obtain an explicit expression relating the Cartan connection associated to $(M,L)$ and the transformed Cartan connection associated to $(M,\bar{L})$. We also express some of the fundamental geometric objects (canonical spray, nonlinear connection, torsion tensors, ...etc.) of $(M,\bar{L})$ in terms of the corresponding objects of $(M,L)$. We characterize the $\beta$-homothetic change and give necessary and sufficient conditions for the vanishing of the difference tensor in certain cases. It is to be noted that many known results of Shibata, Matsumoto, Hashiguchi and others are retrieved as special cases from this work.