-> FB8 -> Experimentalphysik -> Gruppe Drees/Becks -> Wuppertaler DELPHI Gruppe -> Pertubative QCD

Paper210:

Energy Dependence of Event Shapes and of alpha_s at LEP 2

(CERN-EP 99-44, Phys. Lett. B456 (1999) 322)

Infrared and collinear safe event shape distributions and their mean values are determined using the data taken at five different centre of mass energies above M_Z with the DELPHI detector at LEP. From the event shapes, the strong coupling alpha_s is extracted in O(alpha_s^2) , NLLA and a combined scheme using hadronisation corrections evaluated with fragmentation model generators as well as using an analytical power ansatz. Comparing these measurements to those obtained at M_Z, the energy dependence (running) of alpha_s is accessible. The logarithmic energy slope of the inverse strong coupling is measured to be
dalpha^-1_s/dlog(Ecm)=1.39+-0.34(stat)+-0.17(syst) ,
in good agreement with the QCD expectation of 1.27.

Talk on DELPHI Seminar (Dez. 98) (restricted, ~430KB).
Comments and answers to Draft 1 as of 18th Jan. 99 (restricted, ~60KB).

Full Text with Figures

Postscript (~830kB)

Individual Figures

Figure 1a: s' distribution (all data), Figure 1b: B_min distribution (all high energy data)

Figure 2a: Thrust 183GeV, Figure 2b: Major 183GeV, Figure 2c: Minor 183GeV, Figure 2d: Oblateness 183GeV

Figure 3a: M_high 183GeV, Figure 3b: B_max 183GeV, Figure 3c: B_sum 183GeV, Figure 3d: M_diff 183GeV

Figure 4a: Thrust 133GeV, Figure 4b: Thrust 161GeV, Figure 4c: Thrust 172GeV, Figure 4d: Thrust 183GeV

Figure 5: Jetrates 183GeV

Figure 6: Means of 1-T and M_high with fit of power ansatz

Figure 8 with full labels:
Figure 8a: O(alpha_s^2) with Power Corrections, Figure 8b: O(alpha_s^2) Figure 8c: NLLA, Figure 8d: O(alpha_s^2)+NLLA (ln R-scheme),

Figure 8 without y-axis labels for combination next to the previous ones:
Figure 8a: O(alpha_s^2) with Power Corrections, Figure 8b: O(alpha_s^2), Figure 8c: NLLA, Figure 8d: O(alpha_s^2)+NLLA (ln R-scheme)

Daniel Wicke 17. Dez. 98. Letzte Änderung 6. Aug. 99.
wicke@wpdu1.physik.uni-wuppertal.de