Evidence for the decays of $\Lambda^+_{c}\to\Sigma^+\eta$ and $\Sigma^+\eta^\prime$

Abstract

We study the hadronic decays of $\Lambda^+_{c}$ to the final states $\Sigma^+\eta$ and $\Sigma^+\eta^\prime$, using an $e^+e^-$ annihilation data sample of 567 pb$^{-1}$ taken at a center-of-mass energy of 4.6 GeV with the BESIII detector at the BEPCII collider. We find evidence for the decays $\Lambda^+_{c}\to\Sigma^+\eta$ and $\Sigma^+\eta^\prime$ with statistical significance of 2.5$\sigma$ and 3.2$\sigma$, respectively. Normalizing to the reference decays $\Lambda_c^+\to\Sigma^+\pi^0$ and $\Sigma^+\omega$, we obtain the ratios of the branching fractions $\frac{{\mathcal B}(\Lambda_c^+\to\Sigma^+\eta)}{{\mathcal B}(\Lambda_c^+\to\Sigma^+\pi^0)}$ and $\frac{{\mathcal B}(\Lambda_c^+\to\Sigma^+\eta^\prime)}{{\mathcal B}(\Lambda_c^+\to\Sigma^+\omega)}$ to be 0.35±0.16±0.03 and 0.86±0.34±0.07, respectively. The upper limits at the 90\% confidence level are set to be $\frac{{\mathcal B}(\Lambda_c^+\to\Sigma^+\eta)}{{\mathcal B}(\Lambda_c^+\to\Sigma^+\pi^0)}<0.58$ and $\frac{{\mathcal B}(\Lambda_c^+\to\Sigma^+\eta^\prime)}{{\mathcal B}(\Lambda_c^+\to\Sigma^+\omega)}<1.2$. Using BESIII measurements of the branching fractions of the reference decays, we determine $\mathcal B({\Lambda_{c}^{+}\rightarrow\Sigma^{+}\eta})=(0.41\pm0.19\pm0.05)\% (<0.68\%)$ and $\mathcal B({\Lambda_{c}^{+}\rightarrow\Sigma^{+}\eta'})=(1.34\pm0.53\pm0.21)\%$ (<1.9%). Here, the first uncertainties are statistical and the second systematic. The obtained branching fraction of $\Lambda_c^+\to\Sigma^+\eta$ is consistent with the previous measurement, and the branching fraction of $\Lambda_{c}^{+}\rightarrow\Sigma^{+}\eta^{\prime}$ is measured for the first time.