0000000000220628
AUTHOR
H. L. Ren
Observation of the $\psi(1^3D_2)$ state in $e^+e^-\to\pi^+\pi^-\gamma\chi_{c1}$ at BESIII
We report the observation of the $X(3823)$ in the process $e^+e^-\to \pi^+\pi^-X(3823) \to \pi^+\pi^-\gamma\chi_{c1}$ with a statistical significance of $6.2\sigma$, in data samples at center-of-mass energies $\sqrt{s}=$4.230, 4.260, 4.360, 4.420 and 4.600~GeV collected with the BESIII detector at the BEPCII electron positron collider. The measured mass of the $X(3823)$ is $(3821.7\pm 1.3\pm 0.7)$~MeV/$c^2$, where the first error is statistical and the second systematic, and the width is less than $16$~MeV at the 90\% confidence level. The products of the Born cross sections for $e^+e^-\to \pi^+\pi^-X(3823)$ and the branching ratio $\mathcal{B}[X(3823)\to \gamma\chi_{c1,c2}]$ are also measu…
Dark photon search in the mass range between 1.5 and 3.4 GeV/c2
Physics letters / B 774, 252 - 257 (2017). doi:10.1016/j.physletb.2017.09.067