Constraints on electron-quark contact interactions and implications to models of leptoquarks and extra /Z bosons

We update the global constraint on four-fermion eeqq contact interactions. In this update, we included the published data of H1 and ZEUS for the 1994-1996 run in the e⁺p mode and the newly published data of H1 for the 1999 run in the e^-p mode. Other major changes are the new LEPII data on hadronic cross sections above 189 GeV, and the atomic parity violation measurement on cesium because of a new and improved atomic calculation, which drives the data within 1σ of the standard model value. The global data do not show any evidence for contact interactions, and we obtain 95% C.L. limits on the compositeness scale. A limit of Λ^eu_LL+(-)>23 (12.5) TeV is obtained. Implications to models of leptoquarks and extra Z bosons are examined.