# Measurements of Weak Decay Asymmetries of $\Lambda_c^+\to pK_S^0$, $\Lambda\pi^+$, $\Sigma^+\pi^0$, and $\Sigma^0\pi^+$

## TL;DR

This study measures decay asymmetries and transverse polarization of $\Lambda_c^+$ baryons in four decay modes using BESIII data, providing new insights and improved precision, including first-time measurements for some modes.

## Contribution

First-time measurement of $\Lambda_c^+$ decay asymmetries and polarization in multiple modes with improved precision, using a full angular analysis of BESIII data.

## Key findings

- Non-zero $\Lambda_c^+$ transverse polarization observed at 2.1$\sigma$ significance.
- Decay asymmetry parameters measured with improved precision for $\Lambda o pK_S^0$, $\Lambda o ext{mode}$, $\Sigma^+ o ext{mode}$, and $\Sigma^0 o ext{mode}$.
- First measurements of asymmetry parameters for $pK_S^0$ and $\Sigma^0 o ext{mode}$ modes.

## Abstract

Using $e^+e^-\to\Lambda_c^+\bar\Lambda_c^-$ production from a 567 pb$^{-1}$ data sample collected by BESIII at 4.6 GeV, a full angular analysis is carried out simultaneously on the four decay modes of $\Lambda_c^+\to pK_S^0$, $\Lambda \pi^+$, $\Sigma^+\pi^0$, and $\Sigma^0\pi^+$. For the first time, the $\Lambda_c^+$ transverse polarization is studied in unpolarized $e^+e^-$ collisions, where a non-zero effect is observed with a statistical significance of 2.1$\sigma$. The decay asymmetry parameters of the $\Lambda_c^+$ weak hadronic decays into $pK_S^0$, $\Lambda\pi^+$, $\Sigma^+\pi^0$ and $\Sigma^0\pi^+$ are measured to be $0.18\pm0.43(\rm{stat})\pm0.14(\rm{syst})$, $-0.80\pm0.11(\rm{stat})\pm0.02(\rm{syst})$, $-0.57\pm0.10(\rm{stat})\pm0.07(\rm{syst})$, and $-0.73\pm0.17(\rm{stat})\pm0.07(\rm{syst})$, respectively. In comparison with previous results, the measurements for the $\Lambda\pi^+$ and $\Sigma^+\pi^0$ modes are consistent but with improved precision, while the parameters for the $pK_S^0$ and $\Sigma^0\pi^+$ modes are measured for the first time.