The multiplicity of solutions for the critical problem involving the fracional p-Laplacian operator

This paper deals with the existence of multiple solutions for the following critical fractional $p$-Laplacian problem \begin{equation*} \left\{ \begin{array}{l} \mathbf{(-}\Delta \mathbf{)}_{p}^{s}u(x)=\lambda \left\vert u\right\vert ^{p-2}u+f(x,u)+\mu g(x,u)\ \text{in }\Omega ,u>0, \\ \\ u=0\text{ on}\ \mathbb{R}^{n}\setminus \Omega ,% \end{array}% \right. \end{equation*}% where $p>1$, $s\in (0,1)$, $\Omega \subset \mathbb{R}^{n}(n>ps),$ be a bounded smooth domain, $\lambda $, $\mu $ are positive parameters and the functions $f,g:\overline{% \Omega }\times \lbrack 0,\infty )\longrightarrow [0,\infty),$ are continuous and differentiable with respect to the second variable. Our main tools are based on variational methods combined with a classical concentration compacteness method.