We report the first observation of the exclusive decay process B → J/ψK1(1270) using a sample of 1102M BB® meson pairs collected in the Belle detector at the KEKB asymmetric energy e+e− collider. We measure branching fractions of B[B0 → J/ψK01(1270)] =(1.30 ± 0.34 ± 0.32) × 10→3 and B[B+ J/ψK+1(1270)] = (1.80 ± 0.34 ± 0.39) × 10−3, where the first error is statistical and the second is systematic. These modes constitute approximately 15% of the total number of B → J/ψX decays. No evidence is seen for B → J/ψK1(1400) and we set an upper limit for this branching fraction.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)