Constraints on neutrino mass in the scenario of vacuum energy interacting with cold dark matter after Planck 2018

In this work, we investigate the constraints on the total neutrino mass in the scenario of vacuum energy interacting with cold dark matter (abbreviated as IΛCDM) by using the latest cosmological observations. We consider four typical interaction forms, i.e. $Q=beta H{rho }_{mathrm{de}}$, $Q=beta H{rho }_{{rm{c}}}$, $Q=beta {H}_{0}{rho }_{mathrm{de}}$, and $Q=beta {H}_{0}{rho }_{{rm{c}}}$, in the IΛCDM scenario. To avoid the large-scale instability problem in interacting dark energy models, we employ the extended parameterized post-Friedmann method for interacting dark energy to calculate the perturbation evolution of dark energy in these models. The observational data used in this work include the cosmic microwave background (CMB) measurements from the Planck 2018 data release, the baryon acoustic oscillation (BAO) data, the type Ia supernovae (SN) observation (Pantheon compilation), and the 2019 local distance ladder measurement of the Hubble constant H₀ from the Hubble Space Telescope. We find that, compared with those in the ΛCDM+$sum {m}_{nu }$ model, the constrains on $sum {m}_{nu }$ are looser in the four IΛCDM+$sum {m}_{nu }$ models. When considering the three mass hierarchies of neutrinos, the constraints on $sum {m}_{nu }$ are tightest in the degenerate hierarchy case and loosest in the inverted hierarchy case. In addition, in the four IΛCDM+$sum {m}_{nu }$ models, the values of coupling parameter β are larger using the CMB+BAO+SN+H₀ data combination than that using the CMB+BAO+SN data combination, and β>0 is favored at more than 1σ level when using CMB+BAO+SN+H₀ data combination. The issue of the H₀ tension is also discussed in this paper. We find that, compared with the ΛCDM+$sum {m}_{nu }$ model, the H₀ tension can be alleviated in the IΛCDM+$sum {m}_{nu }$ model to some extent.