Puzzles in charmed baryon semileptonic decays

Abstract

Large apparent $SU(3)_F$ breaking and a tension with lattice QCD have recently emerged in semileptonic decays of singly charmed baryons, hinting at either an unexpected hadronic mechanism or new physics. We formulate a framework that systematically matches lattice-QCD inputs onto an $SU(3)_F$ analysis including first-order symmetry breaking. We predict ${\mathcal{B}}(Ξ_c^+\toΣ^0\ell^+ν_\ell)/{\mathcal{B}}(Ξ_c^+\toΞ^0\ell^+ν_\ell)=(2.6\pm0.3)\%,$ and ${\mathcal{B}}(Ξ_c^+\toΛ^0\ell^+ ν_\ell)/{\mathcal{B}}(Ξ_c^+\toΞ^0\ell^+ν_\ell)=(1.1\pm0.1)\%$, whose precise measurements would cleanly determine the origin of the anomalously large $SU(3)_F$ breaking.

Figures (2)

• Figure 1: The numerical results of form factors $f_{\perp}$, $f_{+}$, $f_{0}$, $g_{\perp}$, $g_{+}$ and $g_{0}$ from the $SU(3)_F$ approach of $\Xi_c^+\rightarrow \Lambda$ and $\Xi_c^+\rightarrow \Sigma^0$.
• Figure 2: The differential decay rates and the estimated number of events for the channels $\Xi_c^+ \to \Sigma^0 e^+ \nu_e$ and $\Xi_c^+ \to \Lambda e^+ \nu_e$ are presented. The $q^2$ dependence of the differential decay rates is shown on the left $Y$-axis of the figures, while the estimated number of events is plotted on the right $Y$-axis.