No Arabic abstract
Using a data sample of 106 million $psi(3686)$ events collected with the BESIII detector operated at the BEPCII storage ring, we study for the first time the decay $chi_{cJ}tophi K^{0}_S K^{pm}pi^{mp}$ and $chi_{cJ}tophi K^{+} K^{-}pi^{0}$ in the E1 radiative transition $psi(3686)togammachi_{cJ}$. The decays are dominated by the three-body decay $chi_{cJ}to phi K^*(892)bar{K}$. We measure branching fractions for this reaction via the neutral and charged $K^*(892)$ and find them consistent with each other within the expectation of isospin symmetry. In the $Kbar{K}pi$ invariant mass distribution a structure near the $K^*(892)bar{K}$ mass threshold is observed, and the corresponding mass and width are measured to be $1412pm4(mathrm{stat.})pm8(mathrm{sys.}) mathrm{MeV}/c^2$ and $Gamma$ = $84pm12(mathrm{stat.})pm40(mathrm{sys.}) mathrm{MeV}$, respectively. The observed state favors an assignment to the $h_1(1380)$, considering its possible $J^{PC}$ and comparing its mass, width and decay mode to those reported in the Particle Data Group.
Using $(106.41pm 0.86) times 10^{6}$ $psi(3686)$ events collected with the BESIII detector at BEPCII, we study for the first time the decay $chi_{cJ}toetaK^+K^-$, where $etatogammarho^{0}$ and $etatoetapi^+pi^-$. A partial wave analysis in the covariant tensor amplitude formalism is performed for the decay $chi_{c1}toetaK^+K^-$. Intermediate processes $chi_{c1}toeta f_0(980)$, $chi_{c1}toeta f_0(1710)$, $chi_{c1}toeta f_2(1525)$ and $chi_{c1}to K^*_0(1430)^{pm}K^{mp}$ ($K^*_0(1430)^{pm}toeta K^{pm}$) are observed with statistical significances larger than 5$sigma$, and their branching fractions are measured.
We perform a theoretical study of the $chi_{cJ} to phi K^* bar K to phi Kpi bar K$ reaction taking into account the $K^* bar K$ final state interaction, which in the chiral unitary approach is responsible, together with its coupled channels, for the formation of the low lying axial vector mesons, in this case the $h_1(1380)$ given the selection of quantum numbers. Based on this picture we can easily explain why in the $chi_{c0}$ decay the $h_1(1380)$ resonance is not produced, and, in the case of $chi_{c1}$ and $chi_{c2}$ decay, why a dip in the $K^+ pi^0 K^-$ mass distribution appears in the 1550-1600 MeV region, that in our picture comes from a destructive interference between the tree level mechanism and the rescattering that generates the $h_1(1380)$ state. Such a dip is not reproduced in pictures where the nominal $h_1(1380)$ signal is added incoherently to a background, which provides support to the picture where the resonance appears from rescattering of vector-pseudoscalar components.
Using a data sample of $(448.1pm2.9)times10^{6}$ $psi(3686)$ decays collected by the BESIII detector at the Beijing Electron Positron Collider (BEPCII), we observe the decays $chi_{cJ}to phiphieta~(J=0,~1,~2)$, where the $chi_{cJ}$ are produced via the radiative processes $psi(3686)togammachi_{cJ}$. The branching fractions are measured to be $mathcal B(chi_{c0}tophiphieta)=(8.41pm0.74pm0.62)times10^{-4}$, $mathcal B(chi_{c1}tophiphieta)=(2.96pm0.43pm0.22)times 10^{-4}$, and $mathcal B(chi_{c2} to phiphieta)=(5.33pm0.52pm0.39) times 10^{-4}$, where the first uncertainties are statistical and the second are systematic. We also search for intermediate states in the $phiphi$ or $etaphi$ combinations, but no significant structure is seen due to the limited statistics.
Hadronic transitions of $chi_{cJ}to eta_{c}pi^{+}pi^{-}$ (J=0, 1, 2) are searched for using a sample of $1.06times 10^{8}$ $psi(3686)$ events collected with the BESIII detector at the BEPCII storage ring. The $etac$ is reconstructed with $K_{S}^{0}K^{+}pi^{-}+c.c.$ and $K^{+}K^{-}pi^{0}$ final states. No signals are observed in any of the three $chi_{cJ}$ states in either $etac$ decay mode. At the 90% confidence level, the upper limits are determined to be $BR(chi_{c0}to eta_{c}pi^{+}pi^{-})<0.07%$, $BR(chi_{c1}to eta_{c}pi^{+}pi^{-})<0.32%$, and $BR(chi_{c2}to eta_{c}pi^{+}pi^{-})<0.54%$. The upper limit of $BR(chi_{c1}to eta_{c}pi^{+}pi^{-}$ is lower than the existing theoretical prediction by almost an order of magnitude. The branching fractions of $chi_{cJ}to K_{S}^{0}K^{+}pi^{-}pi^{+}pi^{-}+c.c.$, $K^{+}K^{-}pi^{+}pi^{-}pi^{0}$, $omega K^{+}K^{-}$ and $phipi^{+}pi^{-}pi^{0}$ (J=0, 1, 2) are measured for the first time.
The decays $chi_{cJ}toSigma^{0}bar{p}K^{+}+{rm c.c.}~(J = 0, 1, 2)$ are studied via the radiative transition $psi(3686)togammachi_{cJ}$ based on a data sample of $(448.1 pm 2.9)times10^{6}$ $psi(3686)$ events collected with the BESIII detector. The branching fractions of $chi_{cJ}toSigma^{0}bar{p}K^{+}+{rm c.c.}~(J = 0, 1, 2)$ are measured to be $(3.03 pm 0.12pm 0.15)times10^{-4}$, $(1.46 pm 0.07pm 0.07)times10^{-4}$, and $(0.91 pm 0.06pm 0.05)times10^{-4}$, respectively, where the first uncertainties are statistical and the second are systematic. In addition, no evident structure is found for excited baryon resonances on the two-body subsystems with the limited statistics.