Weighing neutrinos in $f(R)$ gravity in light of BICEP2

TL;DR

This paper uses recent cosmological data, including BICEP2, to constrain neutrino masses within $f(R)$ gravity, showing that B-modes help distinguish effects of neutrinos and modified gravity, and reconcile tensor-to-scalar ratio tensions.

Contribution

It demonstrates that BICEP2 B-mode measurements can break degeneracies in $f(R)$ gravity models with massive neutrinos, providing new constraints and resolving observational tensions.

Findings

Non-zero $B_0$ at 68% confidence with BICEP2 data

B-modes help break degeneracy between neutrino mass and $f(R)$ gravity

Reconciliation of tensor-to-scalar ratio tension between Planck and BICEP2

Abstract

We constrain the neutrino mass in $f(R)$ gravity using the latest observations from the Planck, BAO and BICEP2 data. We find that the measurement on the B-modes can break the degeneracy between the massive neutrinos and the $f(R)$ gravity. We find a non-zero value of the Compton wavelengths $B_{0}$ at a $68\%$ confidence level for the $f(R)$ model in the presence of massive neutrinos when the BICEP2 data is used. Furthermore, the tension on the tensor-to-scalar ratios between the measured values from Plank and BICEP2 is significantly reconciled in our model.