A new measure of tension between experiments

TL;DR

The paper introduces a new measure for assessing tension between cosmological datasets that avoids common issues of existing tests, and demonstrates its effectiveness on Planck data, finding no significant discrepancies.

Contribution

A novel tension measure similar to Bayesian evidence ratio that is free from prior volume dependence and Gaussianity assumptions, tested on cosmological models and Planck data.

Findings

New tension measure performs well on Gaussian and non-Gaussian likelihoods.

Applied to Planck data, found no significant tension in ΛCDM parameters.

Supports consistency of Planck TT and EE measurements.

Abstract

Tensions between cosmological measurements by different surveys or probes have always been important --- and are presently much discussed --- as they may lead to evidence of new physics. Several tests have been devised to probe the consistency of datasets given a cosmological model, but they often have undesired features such as dependence on the prior volume, or burdensome requirements such as that of near-Gaussian posterior distributions. We propose a new quantity, defined in a similar way as the Bayesian evidence ratio, in which these undesired properties are absent. We test the quantity on simple models with Gaussian and non-Gaussian likelihoods. We then apply it to data from the Planck satellite: we investigate the consistency of $\Lambda$CDM model parameters obtained from TT and EE angular power spectrum measurements, as well as the mutual consistency of cosmological parameters obtained from large scale (multipoles, $\ell<1000$) and small scale ($\ell \geq 1000$) portions of each measurement and find no significant discrepancy in the six-dimensional $\Lambda$CDM parameter space.