Determination of alpha(S) using jet rates at LEP with the OPAL detector

Abbiendi, G. and Ainsley, C. and Akesson, P. F. and Alexander, G. and Anagnostou, G. and Anderson, K. J. and Asai, S. and Axen, D. and Bailey, I. and Barberio, E. and Barillari, T. and Barlow, R. J. and Batley, R. J. and Bechtle, P. and Behnke, T. and Bell, K. W. and Bell, P. J. and Bella, G. and Bellerive, A. and Benelli, G. and Bethke, S. and Biebel, O. and Boeriu, O. and Bock, P. and Boutemeur, M. and Braibant, S. and Brown, R. M. and Burckhart, H. J. and Campana, S. and Capiluppi, P. and Carnegie, R. K. and Carter, A. A. and Carter, J. R. and Chang, C. Y. and Charlton, D. G. and Ciocca, C. and Csilling, A. and Cuffiani, M. and Dado, S. and De Roeck, A. and De Wolf, E. A. and Desch, K. and Dienes, B. and Donkers, M. and Dubbert, J. and Duchovni, E. and Duckeck, G. and Duerdoth, T. P. and Etzion, E. and Fabbri, F. (2006) Determination of alpha(S) using jet rates at LEP with the OPAL detector. European Physical Journal C: Particles and Fields, 45 (3). pp. 547-568. ISSN 1434-6044

Abstract

Hadronic events produced in e(+)e(-) collisions by the LEP collider and recorded by the OPAL detector were used to form distributions based on the number of reconstructed jets. The data were collected between 1995 and 2000 and correspond to energies of 91 GeV, 130-136 GeV and 161-209 GeV. The jet rates were determined using four different jet-finding algorithms (Cone, JADE, Durham and Cambridge). The differential two-jet rate and the average jet rate with the Durham and Cambridge algorithms were used to measure alpha(S) in the LEP energy range by fitting an expression in which O(alpha(2)(S)) calculations were matched to a NLLA prediction and fitted to the data. Combining the measurements at different centre-of-mass energies, the value of alpha(s)(Mz) was determined to be as(Mz) = 0.1177 +/- 0.0006 (stat.) +/- 0.0012 (expt.) +/- 0.0010 (had.) +/- 0.0032 (theo.)