The photon polarization in radiative <italic>D</italic> decays, phenomenologically.

We work out the phenomenology of untagged time-dependent analysis with radiative D0<inline-graphic></inline-graphic>-decays into CP eigenstates, which allows to probe the photon polarization by means of the charm mesons’ finite width difference. We show that D0→ϕγ<inline-graphic></inline-graphic> or D0→K¯0∗γ<inline-graphic></inline-graphic> decays, which are SM-dominated, or SM-like, respectively, together with U-spin allow to obtain chirality-predictions for radiative decay amplitudes. The order of magnitude of wrong-chirality contributions in the SM can be cross-checked with an up-down asymmetry in D0→K¯10(→K¯ππ)γ<inline-graphic></inline-graphic>. We explore the sensitivity to new physics in |Δc|=|Δu|=1<inline-graphic></inline-graphic> dipole couplings in the decays D0→ρ0γ<inline-graphic></inline-graphic>. We point out the possibility to test the SM with Ds→K1+(→Kππ)γ<inline-graphic></inline-graphic> decays. [ABSTRACT FROM AUTHOR]