We report the results of several studies of the ${\Lambda }_c^{+}{\pi }^{+}{\pi }^{-}X$ final state in continuum $e^{+}{e}^{-}$ annihilation data collected by the Belle detector. An analysis of angular distributions in ${\Lambda }_c(2880{)}^{+}\to {\Sigma }_c(2455{)}^{0,++}{\pi }^{+,-}$ decays strongly favors a ${\Lambda }_c(2880{)}^{+}$ spin assignment of $\frac{5}{2}$ over $\frac{3}{2}$ or $\frac{1}{2}$. We find evidence for ${\Lambda }_c(2880{)}^{+}\to {\Sigma }_c(2520{)}^{0,++}{\pi }^{+,-}$ decay and measure the ratio of ${\Lambda }_c(2880{)}^{+}$ partial widths $\Gamma \mathbf{(}{\Sigma }_c(2520)\pi \mathbf{)}/\Gamma \mathbf{(}{\Sigma }_c(2455)\pi \mathbf{)}=0.225\pm 0.062\pm 0.025$. This value favors the ${\Lambda }_c(2880{)}^{+}$ spin-parity assignment of ${\frac{5}{2}}^{+}$ over ${\frac{5}{2}}^{-}$. We also report the first observation of ${\Lambda }_c(2940{)}^{+}\to {\Sigma }_c(2455{)}^{0,++}{\pi }^{+,-}$ decay and measure ${\Lambda }_c(2880{)}^{+}$ and ${\Lambda }_c(2940{)}^{+}$ mass and width parameters. These studies are based on a $553{\mathrm{fb}}^{-1}$ data sample collected at or near the ${\rm Y}(4S)$ resonance at the KEKB collider.

• Received 12 January 2007

DOI:https://doi.org/10.1103/PhysRevLett.98.262001