Precise Measurement of the Chromoelectric Dipole Moment of the Charm Quark

The combined symmetry of charge conjugation and parity (CP) is tested in the hadronic transition ψ(3686)→π^{+}π^{-}J/ψ, using a dataset of (2712.4±14.3)×10^{6}  ψ(3686) events collected by the BESIII detector at the BEPCII collider. The resulting asymmetry observable is A_{CP}=(0.6±1.8±0.1)×10^{-4}, which is determined by combining the two channels J/ψ→e^{+}e^{-} and J/ψ→μ^{+}μ^{-}. Additionally, by considering the relationship between the chromoelectric dipole moment (CEDM) and the A_{CP} observable derived from the quantum chromodynamics multipole expansion theory based on the Chen-Kuang model and the Cornell potential model, we obtain the results of charm quark's CEDM with d_{c}^{'}=(2.6±7.8±0.4±0.6)×10^{-16}  e cm, and d_{c}^{'}=(3.5±10.5±0.6±0.5)×10^{-16}  e cm, respectively. The uncertainties are statistical, systematic, and theoretical, respectively. These results correspond to an upper limit of |d_{c}^{'}|<2.1×10^{-15}  e cm at 90% confidence level, representing an order of magnitude improvement in sensitivity compared to the previous direct bound using the same decay process.