No Arabic abstract
We search for the process $e^{+}e^{-}rightarrow pi ^{+}pi ^{-} chi_{cJ}$ ($J=0,1,2$) and for a charged charmonium-like state in the $pi ^{pm} chi_{cJ}$ subsystem. The search uses data sets collected with the BESIII detector at the BEPCII storage ring at center-of-mass energies between 4.18 GeV and 4.60 GeV. No significant $pi ^{+}pi ^{-} chi_{cJ}$ signals are observed at any center-of-mass energy, and thus upper limits are provided which also serve as limits for a possible charmonium-like structure in the invariant $pi ^{pm} chi_{cJ}$ mass.
Using $4.479 times 10^{8}$ $psi(3686)$ events collected with the BESIII detector, we search for the decays $psi(3686) rightarrow e^{+}e^{-}chi_{c0,1,2}$ and $chi_{c0,1,2} rightarrow e^{+}e^{-}J/psi$. The decays $psi(3686) rightarrow e^{+}e^{-}chi_{c0,1,2}$ and $chi_{c0,1,2} rightarrow e^{+}e^{-}J/psi$ are observed for the first time. The measured branching fractions are $mathcal{B}(psi(3686) rightarrow e^{+}e^{-}chi_{c0,1,2}) = (11.7 pm 2.5 pm 1.0)times10^{-4}$, $(8.6 pm 0.3 pm 0.6)times10^{-4}$, $(6.9 pm 0.5 pm 0.6)times10^{-4}$, and $mathcal{B}(chi_{c0,1,2} rightarrow e^{+}e^{-}J/psi) = (1.51 pm 0.30 pm 0.13)times10^{-4}$, $(3.73 pm 0.09 pm 0.25)times10^{-3}$, $(2.48 pm 0.08 pm 0.16)times10^{-3}$. The ratios of the branching fractions $frac{mathcal{B}(psi(3686) rightarrow e^{+}e^{-}chi_{c0,1,2})}{mathcal{B}(psi(3686) rightarrow gammachi_{c0,1,2})}$ and $frac{mathcal{B}(chi_{c0,1,2} rightarrow e^{+}e^{-}J/psi)}{mathcal{B}(chi_{c0,1,2} rightarrow gamma J/psi)}$ are also reported.
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.
Using a data sample of $1.06 times 10^{8}$ $psip$ events collected with the BESIII detector in 2009, the branching fractions of $chi_{cJ}to pbar{n}pi^{-}$ and $chi_{cJ}to pbar{n}pi^{-}pi^{0}$ ($J$=0,1,2) are measured{Throughout the text, inclusion of charge conjugate modes is implied if not stated otherwise.}. The results for $chi_{c0}to pbar{n}pi^{-}$ and $chi_{c2}to pbar{n}pi^{-}$ are consistent with, but much more precise than those of previous measurements. The decays of $chi_{c1}to pbar{n}pi^{-}$ and $chi_{cJ}to pbar{n}pi^{-}pi^{0}$ are observed for the first time.
Using data collected with the BESIII detector operating at the Beijing Electron Positron Collider, we search for the process $e^+e^-rightarrow eta_ceta pi^+pi^-$. The search is performed using five large data sets recorded at center-of-mass energies of 4.23, 4.26, 4.36, 4.42, and 4.60 GeV. The $eta_c$ meson is reconstructed in 16 exclusive decay modes. No signal is observed in the $eta_c$ mass region at any center-of-mass energy. The upper limits on the reaction cross sections are determined to be 6.2, 10.8, 27.6, 22.6 and 23.7 pb at the 90% confidence level at the center-of-mass energies listed above.
Decays of the chi_{cJ} states (J=0, 1, 2) to Lambda Lambda bar pi^{+} pi^{-}, including processes with intermediate Sigma(1385), are studied through the E1 transition psi-->gamma chi_{cJ} using 106 million psi events collected with the BESIII detector at BEPCII. This is the first observation of chi_{cJ} decays to the final state LambdaLambda bar pi^{+}pi^{-}. The branching ratio of the intermediate process chi_{cJ}-->Sigma(1385)^{+/-} bar{Sigma}(1385)^{-/+} is also measured for the first time, and the results agree with the theoretical predictions based on the color-octet effect.