03-2
觀測到雙Cabibbo壓低衰變D+ → K+ π+ π− π0以及D+ → K+ ω的證據
Using 2.93 fb−1 of e+e− collision data collected at a center-of-mass energy of 3.773 GeV with the BESIII detector, the first observation of the doubly Cabibbo-suppressed decay D+ →K+ π+ π- π0 is reported. After removing decays that contain narrow intermediate resonances, including D+ →K+ η, D+ → K+ ω, and D+→K+ϕ, the branching fraction of the decay D+ →K+ π+ π-π0 is measured to be (1.13±0.08stat±0.03syst)×10−3. The ratio of branching fractions of D+ →K+ π+ π−π0 over D+ →K−π+ π+ π0 is found to be (1.81±0.15)%, which corresponds to (6.28±0.52)tan4θC, where θC is the Cabibbo mixing angle. This ratio is significantly larger than the corresponding ratios for other doubly Cabibbo-suppressed decays. The asymmetry of the branching fractions of charge-conjugated decays D±→K±π±π∓π0 is also determined, and no evidence for CP violation is found. In addition, the first evidence for the D+ →K+ ω decay, with a statistical significance of 3.3σ, is presented and the branching fraction is measured to be B(D+ →K+ ω)=(5.7−2.1+2.5stat±0.2syst)×10−5.
Observation of the Doubly Cabibbo-Suppressed Decay D+ → K+ π+ π− π0 and Evidence for D+ → K+ ω
M. Ablikim et al. (BESIII Collaboration)
Phys. Rev. Lett. 125, 141802 (2020)
https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.125.141802