The End of Easy Phenomenology for CMB Experiments: A Case Study in the Dark Sector

Understand

The precision of Cosmic Microwave Background (CMB) experiments, specifically its lensing reconstruction, has reached the limit where non-linear corrections cannot be ignored.

• Neglecting these corrections results in biased constraints on cosmological parameters.
• In this work, we use lensing data from Planck and the South Pole Telescope third generation camera (SPT-3G) taken in 2018 to highlight the impact of these biases in two ways.
• First, we estimate the shifts due to ignoring non-linear corrections in $\Lambda$CDM.