  Anti-de Sitter vacuum, which correspond to a negative cosmological constant
(CC), is theoretically important and well-motivated. It is interesting to see
whether current data can allow the existence of a negative CC not. In this
paper, we perform the MCMC analysis for the $w_0w_a$CDM+CC model using recent
DESI BAO measurements combined with Planck CMB and Pantheon Plus dataset. The
results reveal that the bestfit energy density of CC is $\Omega_\Lambda\sim
-0.3$ and the fitting to DESI is slightly improved, while $\Omega_\Lambda=0$ is
also $1\sigma$ consistent.
