Measurement of event shape variables in deep-inelastic scattering at HERA
Published online: 30 March 2006
Deep-inelastic ep scattering data taken with the H1 detector at HERA and corresponding to an integrated luminosity of 106 pb-1 are used to study the differential distributions of event shape variables. These include thrust, jet broadening, jet mass and the C-parameter. The four-momentum transfer Q is taken to be the relevant energy scale and ranges between 14 GeV and 200 GeV. The event shape distributions are compared with perturbative QCD predictions, which include resummed contributions and analytical power law corrections, the latter accounting for non-perturbative hadronisation effects. The data clearly exhibit the running of the strong coupling αs(Q) and are consistent with a universal power correction parameter α0 for all event shape variables. A combined QCD fit using all event shape variables yields αs(mZ)=0.1198±0.0013 +0.0056 -0.0043 and α0=0.476±0.008 +0.018 -0.059.
© Springer-Verlag, 2006