Can f(Q) gravity challenge ΛCDM ?

Nonmetricity theories and aspects of gauge symmetry

“…Nevertheless, Weyl geometry has gotten back to scene through proposals to unify the standard model of particles with gravity [59,60,[62][63][64][65]102] and also by looking for applications in cosmology [103,104], among other interesting physical implications. This is not to mention recent resurrection of Weyl's ideas through a generalization of the nonmetricity condition: ∇ α g µν = −Q αµν , which together with the requirement (17), are the basis of the symmetric teleparallel theories of gravity [32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][91][92][93][94][95][96][97][98][99], including the so called coincident general relativity [89,100,101]. It is clumsy that, but a very few works [55,57] one can not find even a mention of the SCE in none of these papers.…”

A designer approach to $f(Q)$ gravity and cosmological implications

“…Nevertheless, let us note that negative values of α can give rise to a lower ISW tail in the temperature-temperature power spectrum [64], a feature that has been proved to be responsible for a better fit to CMB data for some MG models when compared to ΛCDM [45,46], and which has recently been confirmed to be true for the case of a f (Q) model with an exact ΛCDM background [65]. Therefore, while large negative values might be excluded this is not the case for small negative ones.…”

“…These, unlike the previous case, are not equivalent. In this work we will focus on the f (Q) formulation given the absence of strong coupling problems for the FLRW background [77] compared to f (T ) gravity and its increasing interest in the cosmological framework [48,63,65], as discussed in the Introduction. Interestingly, f (Q) gravity introduces at least two additional scalar propagating degrees of freedom which disappear around maximally symmetric backgrounds [77].…”

“…Regarding linear perturbations in f (Q) gravity, in particular for the f (Q) model which mimics an exact ΛCDM expansion history, modifications in the evolution of matter density fields were tested against redshift space distortions (RSD) data, showing the ability for the model to alleviate the σ 8 tension [48], while measurable effects have been identified to characterize the matter power spectrum, the lensing effect on the CMB angular power spectrum, CMB temperature anisotropies and the Gravitational Waves (GWs) propagation [64]. A joint analysis of CMB, BAO, RSD, SNIa, Weak Lensing (WL) and Galaxy Clustering (GC) data, was able to strongly constrain the model's parameter and it was found that the model can actually challenge the ΛCDM scenario [65]. Besides these results, f (Q) gravity has been the subject of a variety of studies in many different directions [66,67,68,69,62,70,71,72,73].…”

Constraining cosmological scaling solutions of a Galileon field

“…Indeed we notice that M4's has a smaller amplitude. It has been found that models with a suppressed ISW tail are statistically favored by CMB data [45,46,83]. On the contrary those with a large de-viation in the late-time ISW source are ruled out [64,84].…”