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Comparison with data

All observables should be measured for both data and MC, to make sure that MC can describe the data in a satisfactory way at all instances. Data and MC were compared for the whole LEP II period to increase the statistics, the individual data set did however also show excellent agreement. Comparisons were made for p_T^min equal to 1.8, 2.05 and 6.0 for normal MC (200 GeV MC extracted as before) and for p_T^min at 2.05 for MC without radiative corrections. In the following plots the data and MC has been cut with the cut-maps and the expected remaining background distributions have been subtracted. The remaining number of events is shown on the y-axis and the following data was examined:

• Observables from the hadronic system for single tag VSAT data is shown in Fig. 7.7. Excellent agreement is seen with p_T^min=2.05, except for very low values of invariant mass and total energy of the hadronic system. There is no visible difference between MC with and without radiative corrections.

• Fig. 7.8 show quantities reconstructed from the tagged electrons in the VSAT double tag data. There is good (within statistical errors) agreement between data and MC with radiative corrections and p_T^min=2.05 is found in all plots.

• Quantities reconstructed the DELPHI hadronic system is shown both from VSAT+VSAT and VSAT+STIC double tag data. This is shown in Fig. 7.9 and 7.10. Once again MC with radiative corrections and p_T^min=2.05 give the best agreement with data.

• Finally the tagged electrons from the STIC+VSAT double tag data were used to extract the invariant mass. This is shown in Fig. 7.11 together with Q² for the tagged electrons and the total energy of the hadronic and electron system.

Figure 7.7: VSAT single tag data.

Figure 7.8: VSAT double tag data, observables taken from the e⁺e^- system.

Figure 7.9: Quantities from the hadronic system in VSAT double tag data, notation as Fig. 7.7.

Figure 7.10: STIC+VSAT double tag data, quantities from the hadronic system.

Figure 7.11: STIC+VSAT double tag data, measurements from the the e⁺e^- system.