A hint for new physics from primordial deuterium

Abstract: The abundance of primordial deuterium formed after Big Bang Nucleosynthesis has been measured to percent-level precision. Predictions for the primordial deuterium abundance have achieved similar precision, but different teams have reported different central values, sometimes resulting in a mild (~2sigma) disagreement with measurement. I will introduce a new method to predict the primordial deuterium abundance using Gaussian Processes, which is robust against analysis choices like model selection, dataset selection, and theory prior. I will illustrate why different groups have found different results, and discuss the new physics implications of these findings.