Swiss-cheese cosmologies with variable G and Λ from the renormalization group

Asymptotic Safety and the Cosmic Coincidence Problem

“…In the latter case AS can explain the recent cosmological constant problem but with fine tuning and without answering about the coincidence problem. However, AS may explain both old and new cosmological constant, as well as the coincidence problem without fine tuning with the AS swiss model first proposed in [6] and further studied and generalised in [9], [10], [8], [7].…”

“…Furthermore, results from a series of papers concerning AS swiss cheese model with an interesting solution of the dark energy problem will be given. [6], [7], [8], [9], [10]. Finally, focusing again on the dark energy model the low energy cosmic evolution of recently developed minimally modified Einstein equations compatible with AS gravity, [11], will be given for the first time.…”

Phenomenological footprints of Λ varying gravity theories inspired from quantum gravity models in the multi-messenger era

“…The parameters that are shown in these equations cannot have any value. For acceptable phenomenology of the late cosmology era, they may obtain the range of values explained in [41][42][43]. Here, k should be understood as the inverse of a characteristic spatial length over which the system's fields are averaged.…”

“…Cosmic voids (low-density systems) are described by a gravity that includes a negative or zero or negligible positive CC while regions of space with clusters of galaxies are associated with positive values of CC of the order of the value used for the ΛCDM model. The exact value of a CC, on the astrophysical scale, is not known; but working with a positive value like in [41,43], it has been proved that it is possible to explain the recent cosmic acceleration without any fine-tuning, something that is unique to the best of our knowledge. Studies [41,43], have as a working assumption a positive CC with a value related to the astrophysical length of the cluster of galaxies.…”

“…The exact value of a CC, on the astrophysical scale, is not known; but working with a positive value like in [41,43], it has been proved that it is possible to explain the recent cosmic acceleration without any fine-tuning, something that is unique to the best of our knowledge. Studies [41,43], have as a working assumption a positive CC with a value related to the astrophysical length of the cluster of galaxies.…”