Measurement of the mass and width of the $\Lambda_c(2625)^+$ and the branching ratios of $\Lambda_c(2625)^+ \to \Sigma_c^{0}\pi^{+}$ and $\Lambda_c(2625)^+ \to \Sigma_c^{++}\pi^{-}$

TL;DR

This paper reports precise measurements of the mass, width, and branching ratios of the $ ext{Lambda}_c(2625)^+$ baryon using a large data sample from the Belle detector, providing data to refine theoretical models.

Contribution

First precise measurement of the mass difference, width upper limit, and branching ratios of $ ext{Lambda}_c(2625)^+$ using full Dalitz plot analysis with 980 fb$^{-1}$ data.

Findings

Mass difference measured to be 341.518 MeV/c$^2$

Width upper limit < 0.52 MeV/c$^2$ at 90% CL

Branching ratios around 5% for specific decay modes

Abstract

Using the entire data sample of $980\,\textrm{fb}^{-1}$ collected with the Belle detector operating at the KEKB asymmetric-energy collider, we report the measurement of the mass, width, and the relative branching ratios of the $\Lambda_c(2625)^+$ charmed baryon. The mass difference between $\Lambda_c(2625)^+$ and $\Lambda_c^+$ is measured to be $M(\Lambda_c(2625)^{+}) - M(\Lambda_c^{+}) = 341.518 \pm 0.006 \pm 0.049\ \mathrm{MeV}/\mathit{c}^2$. The upper limit on the width is measured to be $\Gamma(\Lambda_c(2625)^+) < 0.52\,\mathrm{MeV}/\textit{c}^2$ at 90\% credibility level. Based on a full Dalitz plot fit, branching ratios with respect to the mode $\Lambda_c(2625)^+ \to \Lambda_c^+ \pi^+ \pi^-$ are measured to be $\frac{\mathcal{B}(\Lambda_c(2625)^+ \to \Sigma_c^{0} \pi^{+})} {\mathcal{B}(\Lambda_c(2625)^+ \to \Lambda_c^+ \pi^{+} \pi^{-})} = (5.19 \pm 0.23 \pm 0.40) \%$ and $\frac{\mathcal{B}(\Lambda_c(2625)^+ \to \Sigma_c^{++} \pi^{-})} {\mathcal{B}(\Lambda_c(2625)^+ \to \Lambda_c^+ \pi^{+} \pi^{-})} = (5.13 \pm 0.26 \pm 0.32) \%$. These measurements can be used to further constrain the parameters of the underlying theoretical models.