Experimental Constraints on the Spin and Parity of the Lambda_c(2880)

TL;DR

This paper determines the spin-parity of Lambda_c(2880) using angular distribution analysis, finds evidence for its decay modes, and measures relevant parameters, providing new insights into its quantum state.

Contribution

The study provides the first evidence for Lambda_c(2940) decay modes and conclusively favors a 5/2+ spin-parity assignment for Lambda_c(2880).

Findings

Lambda_c(2880) has spin 5/2.

Evidence for Lambda_c(2940)->Sigma_c(2455)pi decay.

Measured ratio of partial widths Gamma[Sigma_c(2520)pi]/Gamma[Sigma_c(2455)pi]=0.225+-0.062+-0.025.

Abstract

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)->Sigma_c(2455)pi decays strongly favors a Lambda_c(2880) spin assignment of 5/2 over 3/2 or 1/2. We find evidence for Lambda_c(2880)->Sigma_c(2520)pi decay and measure the ratio of Lambda_c(2880) partial widths Gamma[Sigma_c(2520)pi]/Gamma[Sigma_c(2455)pi]=0.225+-0.062+-0.025. This value favors the Lambda_c(2880) spin-parity assignment of 5/2+ over 5/2-. We also report the first observation of Lambda_c(2940)->Sigma_c(2455)pi decay and measure Lambda_c(2880) and Lambda_c(2940) parameters. These studies are based on a 553/fb data sample collected at or near the Upsilon(4S) resonance, at the KEKB collider.