Measurements Of The Branching Fractions For Th D→(?)πω Decays At BESⅢ

ψ(3770)is the lightest charmonium state composed of cc above the charm meson pair threshold.Hadronic decay process of charm meson can occur through external emission of W boson,internal emission of W boson,exchange of W boson and so on.Since the discovery of D meson in 1976,the hadronic decays of D meson have been extensively investigated in various experiments.Nevertheless,the existing measurements of the D hadronic decays involving anω meson in the final state are still very poor,due to the limit statistics and high backgrounds.By analyzing the 2.93 fb-1 data taken at the center-of-mass energy of(?)=3.773 GeV with the BESⅢ detector at the BEPCII collider,adopting double tag method,the absolute branching fractions of the three hadronic decays of D0→K-π+ω,D0→KS0π0ω and D+→ KS0π+ωare measured.In this analysis,we used the nine single tags to reconstruct the D meson,D0 meson was reconstructed with three hadronic decays:D0→K+π-,D0→K+π-π0,D0→K+π-π-π+.D-meson was reconstructed with six hadronic decays,D-→K+π-π-,D-→KS0π-,D-→K+π-π-π0,D-→KS0π-π0,D-→KS0π-π-π+ and D-→K+K-π-.By fitting the distribution of MrmBC spectrum of D meson in data and MC respectively,the event number of corresponding nine single tags and the detection efficiency of corresponding nine single tags were obtained.By analyzing inclusive MC,it was found that the main background of the three signal tags come from D0→K-π+π+π-π0,D0→KS0π0π+π-π0 and D+→KS0π+π+π-π0,respectively.The data and MC samples were fitted by two-dimensional fitting method to obtain the number of observe events and the detection efficiency of the three signal tags.For the hadron decay D0(+)→sig,the formula for the branching fraction is as follows Finally,the branching fractions of the three signal tags are measured to be B(D0→KS0π0ω)=(0.74 ± 0.05 ± 0.04)× 10-2 and B(D+→ KS0π+ω)=(0.60 ± 0.04 ± 0.03)× 10-2.where the first uncertainties are statistical and the second are systematic.The branching fraction of D0 →K-π+ω is measured with significantly improved precision by fivefold,compared to the result in the Particle Data Group(PDG).Meanwhile,the other two branching fractions of D0→KS0π0ω and D+→KS0π+ω are measured for the first time.These results are important to understand the isospin symmetry in the decays of D→Kπω.