The photon polarization in radiative D decays, phenomenologically

We work out the phenomenology of untagged time-dependent analysis with radiative D0-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 or D0 → ¯K 0∗ γ decays, which are SM-dominated, or SM-like, respectively, together with Uspin 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 0 1 (→ ¯K ππ)γ . We explore the sensitivity to new physics in |c| = |u| = 1 dipole couplings in the decays D0 → ρ0γ .We point out the possibility to test the SM with Ds → K+ 1 (→ Kππ)γ decays.