Fitting f(Q,T) gravity models with a ΛCDM limit using H(z) and Pantheon data

Abstract

We proposed five f(Q,T) models, which are an extension of symmetric teleparallel gravity, where Q is the non-metricity and T is the trace of the stress–energy tensor. By taking specific values of their parameters, these models have a ΛCDM limit. Using cosmic chronometers and supernovae Ia data, we found that our models are consistent with ΛCDM at a 95% confidence level. To see whether one of these models can challenge ΛCDM at a background perspective, we computed the Bayesian evidence for them and ΛCDM. According to it, the concordance model is preferred over four of them, showing a weak preference against f(Q,T)=−Q/GN+bT and f(Q,T)=−(Q+2Λ)/GN+bT, a substantial preference against f(Q,T)=−(Q+2H02c(Q/(6H02))n+1)/GN+bT, and a strong preference against f(Q,T)=−(Q+2H02c(Q/(6H02))n+1+2Λ)/GN+bT. Interestingly, a model including a T2 dependence (f(Q,T)=−(Q+2Λ)/GN−((16π)2GNb)/(120H02)T2) showed a substantial preference against ΛCDM. Therefore, we encourage further analyses of this model to test its viability outside the background perspective.