Prospects for improved ${\Lambda }_c$ branching fractions

Abstract

The experimental uncertainty on the branching fraction $\text{b}({\Lambda }_c\to p{K}^{-}{\pi }^{+})=(5.0\pm 1.3)$ has not decreased since 1998, despite a much larger data sample. Uncertainty in this quantity dominates that in many other quantities, including branching fractions of ${\Lambda }_c$ to other modes, branching fractions of $b$-flavored baryons, and fragmentation fractions of charmed and bottom quarks. Here we advocate a lattice QCD calculation of the form factors in ${\Lambda }_c\to \Lambda {\ell }^{+}{\nu }_{\ell }$ (the case $\ell =e^{+}$ is simpler as the mass of the lepton can be neglected). Such a calculation would yield an absolute prediction for the rate for ${\Lambda }_c\to \Lambda {\ell }^{+}{\nu }_{\ell }$. When combined with the ${\Lambda }_c$ lifetime, it could provide a calibration for an improved set of ${\Lambda }_c$ branching fractions as long as the accuracy exceeds about 25%.

Comments: 8 pages, 2 figures, version to be published in Phys.\ Rev.\ D