  Rare $\vert \Delta c \vert=\vert \Delta u \vert=1$ processes uniquely probe
flavor in the Standard Model and beyond from the up-type quark sector.
Opportunities to search for BSM physics in charm arise from the severe GIM
suppression which kills SM contributions to leptonic axial-vector contributions
and suppresses CP violation. Semileptonic decays of charmed hadrons offer a
variety of clean null test observables, featuring new physics effects which are
even enhanced by resonance contributions. In particular, angular observables in
three- and self-analyzing four-body baryon decays, such as $\Lambda_c\to p
\ell^+\ell^-$ and $\Xi_c^+\to\Sigma^+(\to p\pi^0)\ell^+\ell^-$,
$\Xi_c^0\to\Lambda^0\,(\to p \pi^-)\ell^+\ell^-$ and $\Omega_c^0\to\Xi^0\,(\to
\Lambda^{0} \pi^0)\ell^+\ell^-$ disentangle possible new physics effects in
electromagnetic dipole couplings $C_7^{(\prime)}$ and (axial-)vector 4-fermion
ones $C^{(\prime)}_{9\,(10)}$. There is sensitivity to BSM couplings as small
as $\sim 0.01$.
