Rare radiative decays of charm baryons

Abstract

We study weak radiative $|\Delta c|=|\Delta u|=1$ decays of the charmed anti-triplett (${\Lambda }_c$, ${\Xi }_c^{+}$, ${\Xi }_c^0$) and sextet (${\Sigma }_c^{++}$, ${\Sigma }_c^{+}$, ${\Sigma }_c^0$, ${\Xi }_c^{\prime +}$, ${\Xi }_c^{\prime 0}$, ${\Omega }_c$) baryons in the standard model (SM) and beyond. We work out $SU(2)$ and $SU(3{)}_F$-symmetry relations. We propose to study self-analyzing decay chains such as ${\Xi }_c^{+}\to {\Sigma }^{+}(\to p{\pi }^0)\gamma$ and ${\Xi }_c^0\to \Lambda (\to p{\pi }^{-})\gamma$, which enable new physics sensitive polarization studies. SM contributions can be controlled by corresponding analysis of the Cabibbo-favored decays ${\Lambda }_c^{+}\to {\Sigma }^{+}(\to p{\pi }^0)\gamma$ and ${\Xi }_c^0\to {\Xi }^0(\to \Lambda {\pi }^0)\gamma$. Further tests of the SM are available with initially polarized baryons including ${\Lambda }_c\to p\gamma$ together with ${\Lambda }_c\to {\Sigma }^{+}\gamma$ decays, or ${\Omega }_c\to {\Xi }^0\gamma$ together with ${\Omega }_c\to (\Lambda ,{\Sigma }^0)\gamma$. In addition, CP-violating new physics contributions to dipole operators can enhance CP-asymmetries up to few percent.

Comments: 30 pages, 3 figures, 15 tables