Charged particle multiplicity in events at 161 and 172 GeV and from the decay of the W boson

P Abreu ,J Strauss ,A Zaitsev ,T Myklebust ,N J Kjaer ,T Ekelöf ,F Waldner ,T Włodek ,W Da Silva ,Yu Belokopytov ,T L Hessing ,C Lacasta ,D Treille ,R Reinhardt ,E I Rosenberg ,A M Wetherell ,V Pozdniakov ,R Contri ,A L Read ,J Libby ,L Mundim ,Erik Johansson ,K H Becks ,S Amato ,A B Fenyuk ,T G M Malmgren ,M Nieuwenhuizen ,U Gasparini ,J H Cowell ,Y Sedykh ,R Mc Nulty ,R Leitner ,G D Alekseev ,F Bianchi ,A Hallgren ,A De Min ,R Strub ,L Roos ,M Bonesini ,H Schneider ,R Marco ,J Guy ,J P Engel ,T Tabarelli ,A Sheridan ,S Stanič ,J Gerber ,P Antilogus ,K Stevenson ,P Poropat ,T Camporesi ,M Verlato ,V Hedberg ,P Morettini ,A M Segar ,E Katsoufis ,W J Murray ,J D Durand ,Yu.a Khokhlov ,M Houlden ,M Davenport ,D Stampfer ,C Garćıa ,C Mariotti ,J Fuster ,S Stapnes ,H Wahlen ,M Begalli ,M Szczekowski ,C K Legan ,H T Phillips ,U Parzefall ,N Smirnov ,L G Tkatchev ,O Klapp ,G Tristram ,Z Hajduk ,O Podobrin ,G Polok ,K Kurvinen ,R Brenner ,P Buschmann ,R Pain ,M Margoni ,G Borisov ,A G Frodesen ,B Loerstad ,A Nomerotski ,N I Zimin ,J Chudoba ,P Delpierre ,L Carroll ,M Górski ,M Boonekamp ,M Colomer ,T Brenke ,C Martínez-Rivero ,P Kubinec ,G Orazi ,G Piana ,U Mjoernmark ,M Michelotto ,G J Barker ,M Berggren ,M Bozzo ,A Maio ,R Jacobsson ,A Grefrath ,W Mitaroff ,I Lippi ,H Rahmani ,W Adam ,P Chochula ,P Jarry ,P Ferrari ,C Kreuter ,J Mašík ,C Matteuzzi ,B Maréchal ,G Wilkinson ,M Regler ,Daniel Bertrand ,L Vitale ,M Nikolenko ,B Golob ,M Sannino ,Ch De La Vaissière ,J J Hernández ,J R Mahon ,C Bosio ,V Ruhlmann-Kleider ,C Parkes ,M V Castillo Gimenez ,E Graziani ,G Matthiae ,G Mc Pherson ,F Cossutti ,O Bärring ,E Migliore ,C Weiser ,D Souza-Santos ,J Cuevas ,P Collins ,B Muryn ,Z Krumstein ,J E Augustin ,A Ruiz ,L Peralta ,D Holthuizen ,M Paganoni ,L Gerdyukov ,F Terranova ,M Koratzinos ,L Lyons ,C Caso ,T J V Bowcock ,C Green ,T Lesiak ,G Crosetti ,G Vegni ,D Edsall ,J Dahm ,O Botner ,V Kostioukhine ,E Piotto ,A Seitz ,P Roudeau ,T Burgsmueller ,S Tzamarias ,E Cortina ,G Sciolla ,S Katsanevas ,Ph Gavillet ,P Paganini ,L Mirabito ,G Grosdidier ,L Di Ciaccio ,M Barbi ,O Smirnova ,F Scuri ,A Stocchi ,P Brückman ,K Hultqvist ,I Kronkvist ,I Stavitski ,R Frühwirth ,P Jönsson ,L Lanceri ,F Formenti ,K Yip ,R Gokieli ,H B Crawley ,M Gandelman ,R Ehret ,A Petrolini ,W Krupinski ,A Trombini ,P Checchia ,Y Arnoud ,P Chliapnikov ,S Ortuno ,E Vallazza ,M A E Schyns ,R.c.a Brown ,J Dolbeau ,L Chaussard ,R Sekulin ,W S C Williams ,R C Shellard ,M Günther ,W Bonivento ,Th D Papadopoulou ,W T Meyer ,A Deghorain ,F Fontanelli ,F Tegenfeldt ,K Muenich ,H Pałka ,F Carena ,H Pernegger ,L Ventura ,G R Smith ,K Mönig ,D Liko ,D Loukas ,A Sadovsky ,S R Hahn ,B Tomé ,M Bigi ,M Pernicka ,F Parodi ,C Joram ,V Uvarov ,F Fulda-Quenzer ,V Malychev ,K Doroba ,D Gelé ,D Zavrtanik ,V Lefébure ,F Matorras ,Α Μάρκου ,J P Tavernet ,Šárka Todorova ,S Marti-Garcia ,C Bourdarios ,H Herr ,M Mazzucato ,H Saarikko ,N Redaelli ,M Wielers ,U Amaldi ,R Nicolaidou ,V Nikolaenko ,J Řídký ,R Mc Kay ,G Rinaudo ,A Tsirou ,P Niss ,A Di Diodato ,A De Angelis ,G Jarlskog ,F Naraghi ,B S Nielsen ,M Witek ,G Leder ,M Feindt ,F Richard ,R Keränen ,S Meyer ,M Mc Cubbin ,J Loken ,M Besançon ,A N Sisakian ,O Solovianov ,P.s.l Booth ,M Caccia ,B T King ,B Jean‐Marie ,A G Olshevski ,M Mulders ,G Cosme ,E Zevgolatakos ,O Tchikilev ,G Damgaard ,A Andreazza ,E Falk ,M Battaglia ,J M Brunet ,C Meroni ,M A Bizouard ,S Cabrera ,M Baubillier ,M Winter ,L Bugge ,D Fassouliotis ,F R Cavallo ,P Baillon ,J Medbo ,D Reid ,O Ullaland ,J M Vizan Garcia ,G Mæhlum ,H Klein ,C Petridou ,M Calvi ,G Eigen ,F L Navarria ,G Smadja ,M Pimenta ,P Branchini ,P P Allport ,P Kokkinias ,V Vrba ,G W Van Apeldoorn ,Yu Gouz ,P Ronchese ,M J Bates ,S Squarcia ,J Drees ,A Augustinus ,S Hoorelbeke ,K Rybicki ,K Österberg ,S Ragazzi ,F Martínez-Vidal ,N N Khovanski ,D Wicke ,C De Clercq ,D Z Toet ,J M Lopez ,M Pegoraro ,E N Gazis ,P Vincent ,I Ajinenko ,C Bérat ,T A Filippas ,Imad Baptiste Laktineh ,M S Bilenky ,A Onofre ,B Åsman ,P Andersson ,A Pullia ,A W Borgland ,P Van Dam ,A Lipniacka ,A C Benvenuti ,V Gracco ,P Kluit ,M R Monge ,J Timmermans ,A Cattai ,K Korcyl ,G Della Ricca ,A Tilquin ,H Mueller ,B Dalmagne ,E Spiriti ,T Moa ,M Chen ,P Negri ,L S Vertogradov ,P Juillot ,D Vilanova ,M Esṕırito Santo ,J Yi ,B Franek ,L Jönsson ,E Fokitis ,W D Apel ,F Mandl ,M Tyndel ,E Higón ,L Serbelloni ,N Neumeister ,A Tonazzo ,S O Holmgren ,G Fanourakis ,J N Jackson ,R Chierici ,A Leisos ,I A Tyapkin ,J Lemonne ,R Alemany ,C Troncon ,K Hamacher ,B Ueberschaer ,W Vénus ,D Gamba ,R Orava ,O Røhne ,T Todorov ,J Wickens ,Kathy Huet ,A Galloni ,G C Zucchelli ,T Adye ,P Lutz ,M Dracos ,B A Khomenko ,T B Skaali ,M Kaiser ,B De Lotto ,F Hahn ,G A Chelkov ,S Fichet ,P Beillière ,M Blume ,N Demaria ,P J Holt ,P Dauncey ,V Chabaud ,G Sajot ,R Silvestre ,A Van Lysebetten ,O Kouznetsov ,A Vodopyanov ,P Sponholz ,P Herquet ,P Zalewski ,D Knoblauch ,P Fischer ,B Bouquet ,F Simonetto ,F Ledroit ,M Szeptycka ,T Rovelli ,H Foeth ,F Verbeure ,K Nawrocki ,J Krstić ,A Baroncelli ,G Ekspong ,P Seager ,A Normand ,M L Turluer ,L K Resvanis ,S Almehed ,L Pape ,D Crennell ,F J Harris ,J P Laugier ,N Pukhaeva ,K A Drees ,P Bambade ,P Privitera ,E Vlasov ,A Ouraou ,K D Brand ,Y Sacquin ,H Dijkstra ,V Lepeltier ,W De Boer ,Ph Charpentier ,S Paiano ,P Rebecchi ,V Chorowicz ,P Rosinský ,K Karafasoulis ,M E Pol ,A Djannati ,P N Ratoff ,C Stănescu ,F Pierre ,O Yushchenko ,D Y Bardin ,V Canale ,S Czellár ,C Walck ,R Lauhakangas ,J P Thomas ,P Siegrist ,W Kucewicz ,U Schwickerath ,J Macnaughton ,A Firestone ,A Perrotta ,L Tortora ,W Oberschulte-Beckmann ,R Janik ,K Belous ,D W Lane ,S Navas ,G Myatt ,P Langefeld ,F Barão ,R Moeller ,D Bertini ,A Romero ,D Blöch ,D Radojičić ,A Passeri ,M Dris ,M Canepa ,K Grzelak ,G P Gopal ,L Gorn ,A Tomaradze ,C Kourkoumelis ,J M Heuser ,J Baudot ,F Kapusta ,P Billoir ,M Elsing ,Ph Gris ,Rui Henriques ,A Zalewska ,S Němeček ,C Jarlskog ,G Lenzen ,V Obraztsov ,R Sosnowski ,P Renton ,A Ferrer ,W Neumann ,J Lämsä ,T Podobnik ,J C Marin ,B Stugu ,N Vassilopoulos ,A Nygren ,C Gaspar ,J Hrubec ,B Erzen ,T Spassov ,K Papageorgiou ,Aurelio Juste Rozas ,E Karvelas ,J Marco ,J Salt ,V Cindro ,P Jałocha ,P Gonçalves ,G Valenti ,S De Brabandere ,F Zach ,E Boudinov ,J Van Eldik ,G Tranströmer ,M Krammer ,T Buran ,L De Paula ,M Lethuillier ,M Reale ,G Zumerle

doi:10.1016/s0370-2693(97)01248-3

Abstract

The data collected by DELPHI in 1996 have been used to measure the average charged particle multiplicities and dispersions in q q ̄ events at centre-of-mass energies of s =161 GeV and s =172 GeV, and the average charge multiplicity in WW events at s =172 GeV. The multiplicities in q q ̄ events are consistent with the evolution predicted by QCD. The dispersions in the multiplicity distributions are consistent with Koba-Nielsen-Olesen (KNO) scaling. The average multiplicity of charged particles in hadronic W decays has been measured for the first time; its value, 19.23±0.74(stat+syst), is consistent with that expected for an e + e − interaction at a centre-of-mass energy equal to the W mass. The charged particle multiplicity in W decays shows no evidence of effects of colour reconnection between partons from different W's at the present level of statistics.

Full Text