${\Xi }_c\to \Xi$ form factors from lattice QCD with domain-wall quarks: A new piece in the puzzle of ${\Xi }_c^0$ decay rates

Abstract

We present a lattice-QCD determination of the vector and axial-vector form factors that describe the charm-baryon semileptonic decays ${\Xi }_c\to \Xi {\ell }^{+}{\nu }_{\ell }$. The calculation uses a domain-wall action for the up, down, and strange quarks, and an anisotropic clover action for the charm quark. We use four ensembles of gauge-field configurations generated by the RBC and UKQCD collaborations, with lattice spacings between 0.111 and 0.073 fm and pion masses ranging from 430 to 230 MeV. We present Standard-Model predictions for the decay rates and branching fractions of ${\Xi }_c^0\to {\Xi }_c^{-}{\ell }^{+}{\nu }_{\ell }$ and ${\Xi }_c^{+}\to {\Xi }_c^0{\ell }^{+}{\nu }_{\ell }$ for $\ell =e,\mu$. In particular, we obtain $\Gamma ({\Xi }_c^0\to {\Xi }^{-}{e}^{+}{\nu }_e)/|V_{cs}{|}^2=0.2515(73){\text{ ps}}^{-1}$ and $\mathcal{B}({\Xi }_c^0\to {\Xi }^{-}{e}^{+}{\nu }_e)=3.58(12)\%$. These values are higher than those predicted by a previous lattice calculation and substantially higher than the experimentally measured values, but consistent with expectations from approximate $SU(3)$ flavor symmetry.

Comments: 21 pages, 8 figures. Typos corrected