Event Shapes and Power Correction Results from HERA
  Inclusive event shape variables have been measured in the Breit Frame for neutral current deep-inelastic positron-proton scattering using the H1 and ZEUS detectors at HERA. The variables thrust, jet broadening, C-parameter, jet mass and two kinds of differential two-jet rate have been studied in the kinematic range 7 < Q < 100 GeV. The Q dependence of the shape variables have been compared with QCD applying power corrections proportional to 1/Q^p to account for hadronisation effects. The concept of power corrections is tested by fitting the strong coupling constant alpha_s and a non-perturbative parameter alpha(p-1)_bar. 
G. J. McCance