New opportunities for rare charm from Z → c\bar{c} decays
the Z pole, such as the FCC-ee or CEPC. In particular, we identify clean null-test observables in D 0→ π + π − ν ν ¯ and in polarized Λ+ c → p ℓ + ℓ − decays with ℓ = e , μ . Complementarity with the LHC [...] modes and charm production with significant polarization. We improve the theoretical description of D 0→ π + π − ν ν ¯ decays and work out the phenomenology of polarization-induced null-test observables in …
