Weak radiative decay $$\Lambda _{c}^{+}\rightarrow \Sigma ^{+}\gamma $$ using light-cone sum rules

We calculate the decay width of $\Lambda_{c}^{+}\to\Sigma^{+}\gamma$ using light-cone sum rules. For initial quark radiation an effective Hamiltonian is constructed, where internal line shrinks to a point. The final studied within full theory. leading twist distribution amplitudes $\Sigma^+$ serve as non-perturbative input for rules calculation, and perturbative kernel calculated at order. branching fraction we obtain ${\cal B}(\Lambda_{c}^{+}\to\Sigma^{+}\gamma)=1.03\pm 0.36 \times 10^{-4}$, which below recent upper limit $<2.6 10^{-4}$ given by Belle collaboration.