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تسجيل مستخدم جديدConcordance Cosmology?
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We propose a new intuitive metric for evaluating the tension between two experiments, and apply it to several data sets. While our metric is non-optimal, if evidence of tension is detected, this evidence is robust and easy to interpret. Assuming a flat $Lambda$CDM cosmological model, we find that there is a modest $2.2sigma$ tension between the DES Year 1 results and the ${it Planck}$ measurements of the Cosmic Microwave Background (CMB). This tension is driven by the difference between the amount of structure observed in the late-time Universe and that predicted from fitting the ${it Planck}$ data, and appears to be unrelated to the tension between ${it Planck}$ and local esitmates of the Hubble rate. In particular, combining DES, Baryon Acoustic Oscillations (BAO), Big-Bang Nucleosynthesis (BBN), and supernovae (SNe) measurements recovers a Hubble constant and sound horizon consistent with ${it Planck}$, and in tension with local distance-ladder measurements. If the tension between these various data sets persists, it is likely that reconciling ${it all}$ current data will require breaking the flat $Lambda$CDM model in at least two different ways: one involving new physics in the early Universe, and one involving new late-time Universe physics.
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