Existence of solutions for nonlinear Dirac equations in the Bopp-Podolsky electrodynamics

Abstract: In this paper, we study the following nonlinear Dirac-Bopp-Podolsky system \begin{equation*} \left\lbrace \begin{array}{rll} \displaystyle{ -i\sum_{k=1}^{3}\alpha_{k}\partial_{k}u+[V(x)+q]\beta u+wu-\phi u}&=f(x,u), \ \ &\text{in}\ \mathbb{R}^3, \ & \ & \ -\triangle\phi+a^2\triangle^2 \phi&=4\pi \vert u\vert^2,\ \ & \text{in}\ \mathbb{R}^3, \end{array} \right. \end{equation*} where $a,q>0,w\in \mathbb{R}$, $V(x)$ is a potential function, and $f(x, u)$ is the interaction term (nonlinearity). First, we give a physical motivation for this new kind of system. Second, under suitable assumptions on $f$ and $V$, and by means of minimax techniques involving Cerami sequences, we prove the existence of at least one pair of solutions $(u,\phi_u)$.