Impact of evolving dark energy on the search for primordial gravitational waves

Recent data seem to suggest a preference for the evolving dark energy (DE). However, if the case is actually so, and not caused by unknown systematics in data, it might impact our understanding about our Universe in an anomalous way due to the shifts of some primary parameters. As an example, we present the search for the primordial gravitational waves, based on the evolving DE. The joint analysis of recent BICEP/Keck cosmic microwave background (CMB) B-mode polarization data with Planck18 CMB, DESI baryon acoustic oscillations and PantheonPlus data shows that the bestfit tensor-to-scalar ratio is $r_{0.05}\sim 0.01$, and the lower bound of $r_{0.05}$ is $\sim 2\sigma$ non-zero.