Quantum singularities in a model of f(R) gravity

The formation of a naked singularity in a model of f(R) gravity having as source a linear elec- tromagnetic field is considered in view of quantum mechanics. Quantum test fields obeying the Klein?Gordon, Dirac and Maxwell equations are used to probe the classical timelike naked sin- gularity developed at r = 0. We prove that the spatial derivative operator of the fields fails to be essentially self-adjoint. As a result, the classical timelike naked singularity remains quantum mechanically singular when it is probed with quantum fields having different spin structures.