Inclusive-jet cross sections in ep collisions at HERA and 
        a comparison of the kt, anti-kt and SIScone jet algorithms

                          ZEUS Collaboration

                              Abstract

For the first time, differential inclusive-jet cross sections have
been measured using the anti-kt and SIScone algorithms. 
The measurements were made with the ZEUS detector at HERA using
an integrated luminosity of 82 pb^-1 in neutral current deep inelastic ep
scattering and photoproduction. The performance and suitability of the
jet algorithms for their use in hadron-like reactions were
investigated by comparing the measurements to those performed with the
kt algorithm. Next-to-leading-order QCD calculations give a good
description of the measurements. Measurements of the ratios of cross
sections using different jet algorithms are also presented; the
measured ratios are well described by calculations including up to
O(alphas^3) terms. Values of alphas(Mz) were extracted from the data;
the results are compatible with and have similar precision to the
value extracted from the kt analysis.