Fractional tempered variational calculus

Abstract: In this paper, we derive sufficient conditions ensuring the existence of a weak solution $u$ for a tempered fractional Euler-Lagrange equations $$ \frac{\partial L}{\partial x}(u,{^C}\mathbb{D}_{a^+}^{\alpha, \sigma} u, t) + \mathbb{D}{b^-}^{\alpha, \sigma}\left(\frac{\partial L}{\partial y}(u, {^C}\mathbb{D}{a^+}^{\alpha, \sigma}u, t) \right) = 0 $$ on a real interval $[a,b]$ and ${^C}\mathbb{D}_{a^+}^{\alpha, \sigma}, \mathbb{D}_{b^-}^{\alpha, \sigma}$ are the left and right Caputo and Riemann-Liouville tempered fractional derivatives respectively of order $\alpha$. Furthermore, we study a fractional tempered version of Noether theorem and we provide a very explicit expression of a constant of motion in terms of symmetry group and Lagrangian for fractional problems of calculus of variations. Finally we study a mountain pass type solution of the cited problem.