Abstract submitted to the
         International Europhysics Conference on High Energy Physics
                  July 12 - 18, 2001, Budapest, Hungary
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            The Q^2 and \bar{E}_T^2 dependence of dijet cross sections in 
                         gamma^*-p interactions at HERA 

                    
                               ZEUS Collaboration



                                    Abstract


      The dependence of the virtual-photon (gamma^*) structure on the photon 
      virtuality, Q^2, and the average transverse energy of the two highest 
      transverse energy jets, \bar{E}_T, has been studied in the range 
      10^{-1} < Q^2 < 10^4 GeV^2 with the ZEUS detector at HERA using an 
      integrated luminosity of 38 pb^{-1}. Events were required to have two 
      jets, with transverse energies E_{T,1}^jet > 7.5 GeV and E_{T,2}^jet
      > 6.5 GeV, using the k_T algorithm in the gamma^*-p frame of reference. 
      The cross section in x_gamma^{obs}, the fraction of the photon's energy 
      participating in the production of the two highest transverse-energy 
      jets, has been measured as a function of Q^2 and \bar{E}_T^2. The ratio 
      of the dijet cross section with x_gamma^{obs} < 0.75 to that with 
      x_gamma^{obs} > 0.75 decreases as Q^2 increases in the three regions of 
      \bar{E}_T^2 studied. The data are compared to the predictions of pQCD 
      using different parton distribution functions of the photon. The 
      measurements can be interpreted in terms of a resolved photon component 
      that falls with Q^2 up to the highest values of \bar{E}_T^2.