Fractional Schr?dinger Equations with Logarithmic and Critical N onlinearities

In this paper,we study a class of the fractional Schr?dinger equations involving logarithmic and critical nonlinearities.By using the Nehari manifold method and the concentration compactness principle,we show that the above problem admits at least one ground state solution and one ground state sign-changing solution.Moreover,by using variational methods,we prove that how the coefficient function of the critical nonlinearity affects the number of positive solutions.The main feature which distinguishes this paper from other related works lies in the fact that it is the first attempt to study the existence and multiplicity for the above problem involving both logarithmic and critical nonlinearities.