Global Monopole in Palatini f(R) gravity

Understand

We consider the space-time metric generated by a global monopole in an extension of General Relativity (GR) of the form $f(\mathcal{R})=\mathcal{R}-\lambda \mathcal{R}^2$.

• The theory is formulated in the metric-affine (or Palatini) formalism and exact analytical solutions are obtained.
• For $\lambda<0$, one finds that the solution has the same characteristics as the Schwarzschild black hole with a monopole charge in Einstein's GR.
• For $\lambda>0$, instead, the metric is more closely related to the Reissner-Nordstr\&#34;{o}m metric with a monopole charge and, in addition, it possesses a wormhole-like structure that allows for the geodesic completeness of the space-time.