First observation of the decays Bbar0(s)→D+sK−π+π− and Bbar0s→Ds1(2536)+π−

摘要

The first observation of the decays Bbar0s→D+sK−π+π− and Bbar0→D+sK−π+π− are reported using an integrated luminosity of 1.0  fb−1 recorded by the LHCb experiment. The branching fractions, normalized with respect to Bbar0s→D+sπ−π+π− and Bbar0s→D+sK−π+π−, respectively, are measured to be ℬ(Bbar0s→D+sK−π+π−)ℬ(Bbar0s→D+sπ−π+π−)=(5.2±0.5±0.3)×10−2 and ℬ(Bbar0→D+sK−π+π−)ℬ(Bbar0s→D+sK−π+π−)=0.54±0.07±0.07, where the first uncertainty is statistical and the second is systematic. The Bbar0s→D+sK−π+π− decay is of particular interest as it can be used to measure the weak phase γ. First observation of the Bbar0s→Ds1(2536)+π−, D+s1→D+sπ−π+ decay is also presented, and its branching fraction relative to Bbar0s→D+sπ−π+π− is found to be ℬ(Bbar0s→Ds1(2536)+π−,D+s1→D+sπ−π+)ℬ(Bbar0s→D+sπ−π+π−)=(4.0±1.0±0.4)×10−3.