Rare radiative charm decays within the standard model and beyond

Abstract

(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image)

We present standard model (SM) estimates for exclusive c [rarr] uγ processes in heavy quark and hybrid frameworks. Measured branching ratios ...... are at or somewhat exceeding the upper range of the SM and suggest slow convergence of the 1/m _D , [alpha] _s-expansion. Model-independent constraints on |[Delta]C|=| [Delta]U |=1 dipole operators from (D ⁰[rarr] [rho] ⁰ γ) data are obtained. Predictions and implications for leptoquark models are worked out. While branching ratios are SM-like CP asymmetries 10% can be induced. In SUSY deviations from the SM can be even larger with CP asymmetries of O(0.1). If [Lambda]_c-baryons are produced polarized, such as at the Z-pole, an angular asymmetry in [Lambda]_c [rarr] pγ decays can be studied that is sensitive to chirality-flipped contributions.