Observation of the ${\chi }_{cJ}$ decays into $p{K}^{-}\bar{\Lambda }\eta +c.c.$

Abstract

By analyzing $(2712.4\pm 14.3)\times 10^6$ $\psi (3686)$ events collected with the BESIII detector operating at the BEPCII collider, the decays ${\chi }_{cJ}\to p{K}^{-}\bar{\Lambda }\eta +c.c.$ ($J=0,1,2$) are observed for the first time, with statistical significances exceeding $5\sigma$ for all three ${\chi }_{cJ}$ states. The measured branching fractions are $\mathcal{B}({\chi }_{c0}\to p{K}^{-}\bar{\Lambda }\eta +c.c.)=(5.3\pm 0.7\pm 0.5)\times 10^{-5}$, $\mathcal{B}({\chi }_{c1}\to p{K}^{-}\bar{\Lambda }\eta +c.c.)=(9.8\pm 0.6\pm 0.6)\times 10^{-5}$, and $\mathcal{B}({\chi }_{c2}\to p{K}^{-}\bar{\Lambda }\eta +c.c.)=(9.3\pm 0.6\pm 0.6)\times 10^{-5}$, where the first uncertainties are statistical and the second are systematic. Structures consistent with the known hyperon resonances $\Lambda (1520)$ and $\bar{\Lambda }(1690)$ are seen in the $p{K}^{-}$ and $\bar{\Lambda }\eta$ invariant mass spectra, respectively. The reported branching fractions include both resonant and non-resonant contributions. These results provide new experimental information on hadronic decays of $P$-wave charmonium states and contribute to the understanding of baryon production and hadronization dynamics in the nonperturbative QCD regime.

13 pages, 7 figures,