Can modified gravity prevent the gravitational collapse to black hole?

It is shown that the theoretical arguments for the unavoidable collapse of massive stars, which are valid within standard general relativity, are not valid in extended gravity. In particular a calculation is reported of neutron stars within a theory obtained from an Einstein-Hilbert action involving a function of $R^{2}-1/2R_{\mu \nu}R^{\mu \nu}$ added to the Ricci scalar $R$. The calculation suggests that within that theory there are stable neutron stars with arbitrarily high baryon number.