Observation of the heavy baryons Σ(b) and Σ(b)

Abstract

We report an observation of new bottom baryons produced in p(p)over-bar collisions at the Tevatron. Using 1.1 fb(-1) of data collected by the CDF II detector, we observe four Λ(0)(b)π(±) resonances in the fully reconstructed decay mode Λ(0)(b)->Λ(+)(c)π(-), where Λ(+)(c)-> pK(-)π(+). We interpret these states as the Σ((*)±)(b) baryons and measure the following masses: m(Σb)(+)=5807.8(-2.2)(+2.0)(stat.) ± 1.7(syst.) MeV/c^(2), m(Σb)(-)=5815.2 ± 1.0(stat.)± 1.7(syst.) MeV/c^(2), and m(Σ(*)(b))-m(Σ(b))=21.2(-1.9)(+2.0)(stat.)(-0.3)(+0.4)(syst.) MeV/c^(2).