Contact Interactions: Results from ZEUS and a Global Analysis

In a search for signatures of physics processes beyond the Standard Model, various eeqq vector contact interaction hypotheses have been tested in the ZEUS experiment. No significant evidence of a contact interaction signal has been found. The analysis is based on NC e+p DIS data corresponding to an integrated luminosity of 47.7 pb-1 and results in 95% CL limits on the effective mass scales Lambda ranging from 1.7 to 5 TeV for the different one-parameter contact interaction scenarios considered. Within the global analysis, including data from other experiments as well, any contact interactions with mass scale below 2.1 TeV are excluded at 95% CL. Combined mass scale limits for specific one-parameter scenarios range from 5.1 to 18 TeV. Upper limits on possible effects to be observed in future HERA, LEP and Tevatron running are estimated. The total hadronic cross-section at LEP and e-p scattering cross-section at HERA are strongly constrained by existing data, whereas large cross-section deviations are still possible for Drell-Yan lepton pair production at the Tevatron.