We report the observation of an isotriplet of excited charmed baryons, decaying into Λ c + π -, Λ c + π 0, and Λ c +π +. We measure the mass differences M(Λ c + π) -M(Λ c +) and widths to be 515.4 -3.1-6.0 +3.2+2.1 MeV/c 2, 61 -13-13 +18+22 MeV for the neutral state; 505.4 -4.6-2.0 +5.8+12.4 MeV/c 2, 62 -23-38 +37+52 MeV for the charged state; and 514.5 -3.1-4.9 +3.4+2.8 MeV/c 2, 75 -13-11 +18+12 MeV for the doubly charged state, where the uncertainties are statistical and systematic, respectively. These results are obtained from a 281 fb -1 data sample collected with the Belle detector near the υ(4S) resonance, at the KEKB asymmetric energy e +e - collider.
ASJC Scopus subject areas
- Physics and Astronomy(all)