Gödel-type solutions within the f(R, Q, P) gravity
J. Nascimento (Departamento de Física, Universidade Federal da Paraíba, João Pessoa, Paraíba, 58051-970, Brazil); A. Petrov (Departamento de Física, Universidade Federal da Paraíba, João Pessoa, Paraíba, 58051-970, Brazil); P. Porfírio (Departamento de Física, Universidade Federal da Paraíba, João Pessoa, Paraíba, 58051-970, Brazil); Ramires Silva (Departamento de Física, Universidade Federal da Paraíba, João Pessoa, Paraíba, 58051-970, Brazil)
In this work, we scrutinize the consistency of spacetime homogeneous Gödel-type metrics within f(R, Q, P) theories of gravity for well-motivated matter sources. As it is well known, such geometries allow for causality violation. We provide general conditions to engender completely causal solutions in a manner completely different from general relativity. We take some specific models, for instance, $$f(R,Q,P)=R -\dfrac{\mu ^{4n+2}}{\left( a R^2+b Q+c P\right) ^n}$$ , to illustrate the general results. Notably, we also find an unusual completely causal vacuum solution in the presence of a non-trivial cosmological constant which corresponds to the case $$m^2=4\omega ^2$$ .