The masses of the ground state heavy baryons consisting of two light (u,d,s)
and one heavy (c,b) quarks are calculated in the heavy-quark--light-diquark
approximation within the constituent quark model. The light quarks, forming the
diquark, and the light diquark in the baryon are treated completely
relativistically. The expansion in v/c up to the second order is used only for
the heavy (b and c) quarks. The diquark-gluon interaction is taken modified by
the form factor describing the light diquark structure in terms of the diquark
wave functions. An overall reasonable agreement of the obtained predictions
with available experimental data and previous theoretical results is found.Comment: 13 pages, 2 figures, version published in Phys. Rev.