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We discuss the radial spectrum of light scalar mesons in the framework ofspectral sum rules in the large-Nc (planar) limit of QCD. Two methods based onthe use of linear radial Regge trajectories are presented. A special emphasisis placed on the appearance of scalar isoscalar state near 0.5 GeV. Within theconsidered sum rules, the existence of this meson (which could be a large-Nccounterpart to the sigma-meson) is closely related with existence of resonancesin the vector channels and on the radial scalar trajectory.

The linear radial spectrum of scalar mesons within the QCD sum rules in the planar limit