Effects of modified gravity on the turnaround radius in cosmology
  We revisit the concept of turnaround radius in cosmology, in the context of
modified gravity. While preliminary analyses were limited to
scalar-tensor/$F(R)$ gravity, we extend the definition and the study of this
quantity to a much broader class of theories including also quantum $R^2$
gravity. The turnaround radius is computed in terms of the parameters of the
theory and it is shown that a deviation not larger than 10\% of this quantity
from its value in Einstein's theory could constrain the model parameters and
even rule out some current theories.
