A perturbative approach to neutron stars in f (T, T) f (T, T) -gravity

We derive a Tolman–Oppenheimer–Volkoff equation in neutron star systems within the modified f (T, T) -gravity class of models using a perturbative approach. In our approach f (T, T) -gravity is considered to be a static spherically symmetric space-time. In this instance the metric is built from a more fundamental vierbein which can be used to relate inertial and global coordinates. A linear function f = T (r) + T (r) + h (T, T) + O (^2) is taken as the Lagrangian density for the gravitational action. Finally we impose the polytropic equation of state of neutron star upon the derived equations in order to derive the mass profile and mass–central density relations of the neutron star in f (T, T) -gravity.