Test of colour reconnection models using three-jet events in hadronic Z decays

S Schael,M Chmeissani,P Perret,L Passalacqua,G.A Blair,E Simopoulou,F Bossi,W Männer,C Borean,F Gianotti,S Xue,B Bloch-Devaux,A Ranieri,A Misiejuk,M.-N Minard,A Valassi,F Hölldorfer,I Videau,G Bencivenni,M Davier,C Geweniger,A Böhrer,G Giannini,I De Bonis,A Blondel,H Wachsmuth,J.M Pascolo,E Merle,P Colas,H Drevermann,S Dessagne,S Bravo,C Zeitnitz,G Mannocchi,S Jin,F Badaud,F Machefert,A Ngac,F Combley,D Schlatter,S Dhamotharan,K Hüttmann,G Sanguinetti,B Pietrzyk,F Ruggieri,P Girtler,P Payre,R Xu,F Kayser,D Fouchez,J Rothberg,P Jussel,M Wunsch,N De Filippis,B Michel,O.J Hayes,A Putzer,A Antonelli,S.R Armstrong,G Capon,P Coyle,G Lütjens,G Hughes,J.G Lynch,J Jousset,V Hepp,H Videau,A Rougé,M De Palma,S Monteil,S Schmeling,R Settles,A Vayaki,G Prange,B Renk,F Foster,B.S Nilsson,J Kile,O Callot,H Ruiz,A Ealet,B Vallage,B Jost,G Ellis,R Barate,G Rudolph,J Boucrot,G Parrini,D Fayolle,S.A Rutherford,W Cameron,R Beuselinck,T Medcalf,F Teubert,B Fabbro,J Nowell,G Leibenguth,H Dietl,R Brunelière,B Tuchming,C Curtil,O Van Der Aa,C Markou,A Moutoussi,K Tittel,Q Ouyang,K Zachariadou,A Pacheco,A David,O Awunor,P Tempesta,F Ranjard,D Kühn ,M Lehto,B Clerbaux,J A Strong ,T Barklow,J.C Thompson,M Martı́nez ,J Lin,C K Bowdery ,S González,R W Clifft ,N Marinelli,A J Finch ,P H Hansen ,A Giassi,P Janot,A Jachołkowska ,M Fernández-Bosman ,W Zhao,T Ziegler,M Smižanská ,U Blumenschein,E Lançon,L Zhang,V Chiarella,D Creanza,A Venturi,R Edgecock ,P R Norton ,P G Verdini ,P Hanke,M R Pearson ,J.M Crespo,J Pütz ,G Rolandi ,J J Ward ,J Kennedy,G N Taylor ,K Berkelman,G Wolf,D.P.S Ferguson,H Stenzel,L Foà,K Jakobs,L.F Thompson,L Duflot,G Davies,I R Tomalin ,J Heß ,R Forty ,T Boccali,D Abbaneo,P Heusse,T Wang,J Guenther ,S Wasserbaech,H Hu,M Frank,A Colaleo,P Negus,W Wiedenmann,G Dissertori,C Delaere,J H Von Wimmersperg-Toeller ,M.G Green,R White,A Kyriakis,C N Booth ,P Teixeira-Dias,A Tilquin,D Pallin,A Giammanco,F Ligabue,F Palla,J Nielsen,P Pérez ,P Azzurri,A Kraan ,C Goy,S Nuzzo,G Iaselli,O Buchmüller,P Spagnolo,E.-E Kluge ,D Décamp ,J Rander,J Harvey,G Mäggi ,R Cavanaugh,S L Wu ,E Focardi,A Tricomi,S Cartwright,Jian Wu ,V O’Shea,R W L Jones ,E V Bouhova-Thacker ,E Kneringer,D Hutchcroft ,Ll Garrido ,K Cranmer,F Cerutti,F F Martin ,G Ganis,M Cattaneo,G Cowan,S Jézéquel,G Sguazzoni,Siegmund Brandt ,M Antonelli,M C Lemaire ,Y S Gao ,J B Hansen ,J J Veillet ,J R Hansen ,X T Huang ,V Ciulli,Р Тенчини ,G Raso,C Grupen,X Wu,P Laurelli,J.-F Grivaz,J D Hansen ,A.‐S Müller ,A S Thompson ,B Trocmé,V Lemaı̂tre ,J K Sedgbeer ,V M Ghete ,A Bonissent,M Kado,G Zito,M Girone,M Villegas,E Fernández ,P J Dornan ,A Sciabà,F Ragusa,G Bagliesi,L Serin,P Hodgson ,J Zhang,Y B Pan ,E Locci,G Selvaggi,L Silvestris,D Boumediene,A Falvard,H He,Danielle Clarke ,A Messineo,P.a Mcnamara ,J P Lees ,A García-Bellido ,A M Litke ,G Zobernig,Y Xie,J C Brient ,P Mató ,M P Casado ,M Maggi,H G Sander ,N A Robertson ,F Murtas

doi:10.1140/epjc/s10052-006-0017-5

Abstract

Hadronic Z decays into three jets are used to test QCD models of colour reconnection (CR). A sensitive quantity is the rate of gluon jets with a gap in the particle rapidity distribution and zero jet charge. Gluon jets are identified by either energy-ordering or by tagging two b-jets. The rates predicted by two string-based tunable CR models, one implemented in JETSET (the GAL model), the other in ARIADNE, are too high and disfavoured by the data, whereas the rates from the corresponding non-CR standard versions of these generators are too low. The data can be described by the GAL model assuming a small value for the R_0 parameter in the range 0.01-0.02.

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