Search for the isospin-violating decays ${\mathbf{\chi }}_{\mathbf{cJ}}\to \mathbf{\Lambda }{\bar{\mathbf{\Sigma }}}^0+\mathbf{c}.\mathbf{c}.$ and ${\mathbf{\eta }}_{\mathbf{c}}\to \mathbf{\Lambda }{\bar{\mathbf{\Sigma }}}^0+\mathbf{c}.\mathbf{c}.$

Abstract

Using a sample of $(2712.4\pm 14.3)\times 10^6$~$\psi (3686)$ events collected with the BESIII detector, we perform a search for the isospin-violating decays ${\chi }_{cJ}\to \Lambda {\bar{\Sigma }}^0+c.c.(J=0,1,2)$ and ${\eta }_c\to \Lambda {\bar{\Sigma }}^0+c.c.$ No significant signal for ${\chi }_{cJ}$ or ${\eta }_c$ is observed in the $\Lambda {\bar{\Sigma }}^0$ invariant mass distribution. The upper limits on the branching fractions at the 90\% confidence level are set to be $\mathcal{B}$(${\chi }_{c0}\to \Lambda {\bar{\Sigma }}^0+c.c.$)$<1.5\times 10^{-6}$, $\mathcal{B}$(${\chi }_{c1}\to \Lambda {\bar{\Sigma }}^0+c.c.$)$<1.6\times 10^{-6}$, $\mathcal{B}$(${\chi }_{c2}\to \Lambda {\bar{\Sigma }}^0+c.c.$)$<1.7\times 10^{-6}$ and $\mathcal{B}$(${\eta }_c\to \Lambda {\bar{\Sigma }}^0+c.c.$)$<6.2\times 10^{-5}$ for the first time.

References in corpus (8)

• TopoAna: A generic tool for the event type analysis of inclusive Monte-Carlo samples in high energy physics experiments
• Hyperon Form Factors & Diquark Correlations
• Determination of the number of $\psi (3686)$ events taken at BESIII
• Further study of the helicity selection rule evading mechanism in ${\eta }_c$, ${\chi }_{c0}$ and $h_c$ decaying to baryon anti-baryon pairs
• Measurements of Baryon Pair Decays of ${\chi }_{cJ}$ Mesons
• Measurements of the branching fractions of $\psi (3686)\to {\bar{\Sigma }}^0\Lambda +c.c.$ and ${\chi }_{cJ(J=0,1,2)}\to \Lambda \bar{\Lambda }$
• Search for a massless particle beyond the Standard Model in the ${\Sigma }^{+}\to p+\mathrm{invisible}$ decay
• Isospin strikes back