  The search for new physics beyond the standard model is proceeding nowadays
intensively along experimental and theoretical lines. We review here the sector
of charm radiative decays in this context. The calculation of $D\to V\gamma$,
$D\to \ell^+\ell^-\gamma$ transitions reveals their unequivocal dominance by
long-distance contributions. On the other hand, the beauty-conserving
charm-changing electroweak transition $B_c\to B_u^*\gamma$ is shown to have
unique properties which make it a promising avenue in the search for new
physics. We describe a calculation of short- and long-distance contributions to
this decay which finds them to be of comparable size. The branching ratio of
this decay in the standard model is estimated to be $\simeq 10^{-8}$.
