Observation of the heavy baryons Sigma(b) and Sigma(b)*

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 Lambda(0)(b)pi(+/-) resonances in the fully reconstructed decay mode Lambda(0)(b)->Lambda(+)(c)pi(-), where Lambda(+)(c)-> pK(-)pi(+). We interpret these states as the Sigma((*)+/-)(b) baryons and measure the following masses: m(Sigma b)(+)=5807.8(-2.2)(+2.0)(stat.)+/- 1.7(syst.) MeV/c(2), m(Sigma b)(-)=5815.2 +/- 1.0(stat.)+/- 1.7(syst.) MeV/c(2), and m(Sigma(*)(b))-m(Sigma(b))=21.2(-1.9)(+2.0)(stat.)(-0.3)(+0.4)(syst.) MeV/c(2).