Observation of an isotriplet of excited charmed baryons decaying to Λc+π -: art. no. 122002

We report the observation of an isotriplet of excited charmed baryons, decaying into Lambda(+)(c)pi(-), Lambda(+)(c)pi(0), and Lambda(+)(c)pi(+). We measure the mass differences M(Lambda(+)(c)pi)-M(Lambda(+)(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 Upsilon(4S) resonance, at the KEKB asymmetric energy e(+)e(-) collider.