Weak radiative decay $\Lambda_{c}^{+}\to\Sigma^{+}\gamma$ using light-cone sum rules

TL;DR

This paper calculates the decay width of the $ ext{Lambda}_c^+ o ext{Sigma}^+ ext{gamma}$ process using light-cone sum rules, providing a theoretical estimate of its branching fraction consistent with experimental limits.

Contribution

It introduces a detailed light-cone sum rules approach to compute the decay width of a charmed baryon radiative decay, incorporating both effective Hamiltonian and full theory treatments.

Findings

Branching fraction estimated at approximately 1.03 x 10^{-4}

Result is below the experimental upper limit from Belle

Method combines effective Hamiltonian with light-cone distribution amplitudes

Abstract

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