Event Shapes and Power Corrections at HERA

Abstract

A measurement of event shape variables in neutral current deep inelastic ep scattering has been made at HERA with the ZEUS detector, using an integrated luminosity of 45.2pb-1. The variables thrust and broadening, with respect to the photon axis and the thrust axis, as well as the jet-mass and C-parameter, have been measured in the current region of the Breit frame in the kinematic range 10 < Q2 < 20480 GeV2 and 0.0006 < x < 0.6. The Q dependence of the event shapes have been compared to QCD predictions using Next-to-Leading Order calculations in conjunction with a power correction model to account for hadronisation. The model is tested by extracting the strong coupling constant alphas(Mz) and a new non-perturbative parameter, alpha0(muI)