Search for neutralino pair production at √s = 189 GeV

European Physical Journal C 19:2 (2001) 201-212

Authors:

P Abreu, W Adam, T Adye, P Adzic, I Ajinenko, Z Albrecht, T Alderweireld, GD Alekseev, R Alemany, T Allmendinger, PP Allport, S Almehed, U Amaldi, N Amapane, S Amato, EG Anassontzis, P Andersson, A Andreazza, S Andringa, N Anjos, P Antilogus, WD Apel, Y Arnoud, B Åsman, JE Augustin, A Augustinus, P Baillon, A Ballestrero, P Bambade, F Barao, G Barbiellini, R Barbier, DY Bardin, G Barker, A Baroncelli, M Battaglia, M Baubillier, KH Becks, M Begalli, A Behrmann, Y Belokopytov, NC Benekos, AC Benvenuti, C Berat, M Berggren, L Berntzon, D Bertrand, M Besancon, N Besson, MS Bilenky, MA Bizouard, D Bloch, HM Blom, L Bol, M Bonesini, M Boonekamp, PSL Booth, G Borisov, C Bosio, O Botner, E Boudinov, B Bouquet, C Bourdarios, TJV Bowcock, I Boyko, I Bozovic, M Bozzo, M Bracko, P Branchini, RA Brenner, P Bruckman, JM Brunet, L Bugge, P Buschmann, M Caccia, M Calvi, T Camporesi, V Canale, F Carena, L Carroll, C Caso, MV Castillo Gimenez, A Cattai, FR Cavallo, P Charpentier, P Checchia, GA Chelkov, R Chierici, P Chliapnikov, P Chochula, V Chorowicz, J Chudoba, K Cieslik, P Collins, R Contri, E Cortina, G Cosme, F Cossutti, M Costa, HB Crawley

Abstract:

A search for pair-production of neutralinos at a LEP centre-of-mass energy of 189 GeV gave no evidence for a signal. This limits the neutralino production cross-section and excludes regions in the parameter space of the Minimal Supersymmetric Standard Model (MSSM).

Search for sleptons in e+e- collisions at √s = 183 to 189 GeV

European Physical Journal C 19:1 (2001) 29-42

Authors:

P Abreu, W Adam, T Adye, P Adzic, I Ajinenko, Z Albrecht, T Alderweireld, GD Alekseev, R Alemany, T Allmendinger, PP Allport, S Almehed, U Amaldi, N Amapane, S Amato, EG Anassontzis, P Andersson, A Andreazza, S Andringa, N Anjos, P Antilogus, WD Apel, Y Arnoud, B Åsman, JE Augustin, A Augustinus, P Baillon, A Ballestrero, P Bambade, F Barao, G Barbiellini, R Barbier, DY Bardin, G Barker, A Baroncelli, M Battaglia, M Baubillier, KH Becks, M Begalli, A Behrmann, Y Belokopytov, NC Benekos, AC Benvenuti, C Berat, M Berggren, L Berntzon, D Bertrand, M Besancon, N Besson, MS Bilenky, MA Bizouard, D Bloch, HM Blom, L Bol, M Bonesini, M Boonekamp, PSL Booth, G Borisov, C Bosio, O Botner, E Boudinov, B Bouquet, C Bourdarios, TJV Bowcock, I Boyko, I Bozovic, M Bozzo, M Bracko, P Branchini, RA Brenner, P Bruckman, JM Brunet, L Bugge, P Buschmann, M Caccia, M Calvi, T Camporesi, V Canale, F Carena, L Carroll, C Caso, MV Castillo Gimenez, A Cattai, FR Cavallo, P Charpentier, P Checchia, GA Chelkov, R Chierici, P Chliapnikov, P Chochula, V Chorowicz, J Chudoba, K Cieslik, P Collins, R Contri, E Cortina, G Cosme, F Cossutti, M Costa, HB Crawley

Abstract:

Data taken by the DELPHI experiment at centre-of-mass energies of 183 GeV and 189 GeV with a total integrated luminosity of 212 pb-1 have been used to search for the supersymmetric partners of the electrons, muons, and taus in the context of the Minimal Supersymmetric Standard Model (MSSM). The decay topologies searched for were the direct decay (ℓ̃ → ℓx̃), producing acoplanar lepton pairs plus missing energy, and the cascade decay (ℓ → ℓx̃02 → ℓγx̃01), producing acoplanar lepton and photon pairs plus missing energy. The observed number of events is in agreement with Standard Model predictions. The 95% CL excluded mass limits for selectrons, smuons and staus are mẽ ≤ 87 GeV/c2, mμ̃ ≤ 80 GeV/c2 and mτ̃ 75 GeV/c2, respectively, for values of μ=-200 GeV/c2 and tanβ=1.5.

Study of dimuon production in photon-photon collisions and measurement of QED photon structure functions at LEP

European Physical Journal C 19:1 (2001) 15-28

Authors:

P Abreu, W Adam, T Adye, P Adzic, I Ajinenko, Z Albrecht, T Alderweireld, GD Alekseev, R Alemany, T Allmendinger, PP Allport, S Almehed, U Amaldi, N Amapane, S Amato, EG Anassontzis, P Andersson, A Andreazza, S Andringa, P Antilogus, WD Apel, Y Arnoud, B Åsman, JE Augustin, A Augustinus, P Baillon, P Bambade, F Barao, G Barbiellini, R Barbier, DY Bardin, G Barker, A Baroncelli, M Battaglia, M Baubillier, KH Becks, M Begalli, A Behrmann, P Beilliere, Y Belokopytov, NC Benekos, AC Benvenuti, C Berat, M Berggren, D Bertrand, M Besancon, M Bigi, MS Bilenky, MA Bizouard, D Bloch, HM Blom, M Bonesini, M Boonekamp, PSL Booth, AW Borgland, G Borisov, C Bosio, O Botner, E Boudinov, B Bouquet, C Bourdarios, TJV Bowcock, I Boyko, I Bozovic, M Bozzo, M Bracko, P Branchini, RA Brenner, P Bruckman, JM Brunet, L Bugge, T Buran, B Buschbeck, P Buschmann, S Cabrera, M Caccia, M Calvi, T Camporesi, V Canale, F Carena, L Carroll, C Caso, MV Castillo Gimenez, A Cattai, FR Cavallo, V Chabaud, P Charpentier, P Checchia, GA Chelkov, R Chierici, P Chliapnikov, P Chochula, V Chorowicz, J Chudoba, K Cieslik, P Collins, R Contri, E Cortina, G Cosme, F Cossutti

Abstract:

Muon pair production in the process e+e- → e+e- μ+μ- is studied using the data taken at LEP1 (√s ≃ mz) with the DELPHI detector during the years 1992-1995. The corresponding integrated luminosity is 138.5 pb-1. The QED predictions have been tested over the whole Q2 range accessible at LEP1 (from several GeV2/c4 to several hundred GeV2/c4) by comparing experimental distributions with distributions resulting from Monte Carlo simulations using various generators. Selected events are used to extract the leptonic photon structure function Fγ2. Azimuthal correlations are used to obtain information on additional structure functions, FγA and FγB, which originate from interference terms of the scattering amplitudes. The measured ratios FγA/Fγ2 and FγB/Fγ2 are significantly different from zero and consistent with QED predictions.

A prototype RICH detector using multi-anode photo multiplier tubes and hybrid photo-diodes

Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment Elsevier 456:3 (2001) 233-247

Authors:

E Albrecht, G Barber, JH Bibby, NH Brook, G Doucas, A Duane, S Easo, L Eklund, M French, V Gibson, T Gys, AW Halley, N Harnew, M John, D Piedigrossi, J Rademacker, B Simmons, N Smale, P Teixeira-Dias, L Toudup, D Websdale, G Wilkingson, SA Wotton

Consistent measurements of αs from precise oriented event shape distributions (vol 14, pg 557, 2000)

EUROPEAN PHYSICAL JOURNAL C 19:4 (2001) 761-763

Authors:

P Abreu, W Adam, T Adye, P Adzic, I Ajinenko, Z Albrecht, T Alderweireld, GD Alekseev, R Alemany, T Allmendinger, PP Allport, S Almehed, U Amaldi, N Amapane, S Amato, EG Anassontzis, P Andersson, A Andreazza, S Andringa, P Antilogus, WD Apel, Y Arnoud, B Åsman, JE Augustin, A Augustinus, M Battaglia, M Baubillier, KH Becks, M Begalli, A Behrmann, P Beilliere, Y Belokopytov, NC Benekos, AC Benvenuti, C Berat, M Berggren, D Bertini, D Bertrand, M Besancon, M Bigi, MS Bilenky, MA Bizouard, D Bloch, HM Blom, M Bonesini, M Boonekamp, PSL Booth, AW Borgland, G Borisov, C Bosio, O Botner, E Boudinov, B Bouquet, C Bourdarios, TJV Bowcock, I Boyko, I Bozovic, M Bozzo, P Branchini, T Brenke, RA Brenner, P Bruckman, JM Brunet, L Bugge, T Buran, T Burgsmueller, B Buschbeck, P Buschmann, S Cabrera, M Calvi, T Camporesi, V Canale, F Carena, L Carroll, C Caso, MVC Gimenez, A Cattai, FR Cavallo, V Chabaud, P Charpentier, L Chaussard, P Checchia, GA Chelkov, R Chierici, P Chliapnikov, P Chochula, V Chorowicz, J Chudoba, K Cieslik, P Collins, R Contri, E Cortina, G Cosme, F Cossutti, JH Cowell, HB Crawley, D Crennell, S Crepe, G Crosetti, JC Maestro, S Czellar, M Davenport, W Da Silva, A Deghorain, G Della Ricca, P Delpierre, N Demaria, A De Angelis, W De Boer, C De Clercq, B De Lotto, A De Min, L De Paula, H Dijkstra, L De Ciaccio, J Dolbeau, K Doroba, M Dracos, J Drees, M Dris, A Duperrin, JD Durand, G Eigen, T Ekelof, G Ekspong, M Ellert, M Elsing, JP Engel, B Erzen, ME Santo, G Fanourakis, D Fassouliotis, J Fayot, M Feindt, A Fenyuk, A Ferrer, E Ferrer-Ribas, F Ferro, S Fichet, A Firestone, U Flagmeyer, H Foeth, E Fokitis, F Fontanelli, B Franck, AG Frodesen, R Fruhwirth, F Fulda-Quenzer, J Fuster, A Galloni, D Gamba, S Gamblin, M Gandelman, C Garcia, C Gaspar, M Gaspar, U Gasparini, P Gavillet, EN Gazis, D Gelel, N Ghodbane, I Gil, F Glege, R Gokieli, B Golob, G Gomez-Ceballos, P Goncalves, IG Caballero, G Gopal, L Gorn, Y Gouz, V Gracco, J Grahl, E Graziani, C Green, HJ Grimm, P Gris, G Grosdidier, K Grzelak, M Gunther, J Guy, F Hahn, S Hahn, S Haider, A Hallgren, K Hamacher, J Hansen, FJ Harris, V Hedberg, S Heising, JJ Hernandez, P Herquet, H Herr, TL Hessing, JM Heuser, E Higon, SO Holmgren, PJ Holt, S Hoorelbeke, M Houlden, J Hrubec, K Huet, GJ Hughes, K Hultqvist, JN Jackson, R Jacobsson, P Jalocha, R Janik, C Jarlskog, G Jarlskog, P Jarry, B Jean-Marie, EK Johansson, P Jonsson, C Joram, P Juillot, F Kapusta, K Karafasoulis, S Katsanevas, EC Katsoufis, R Keranen, BP Kersevan, BA Khomenko, NN Khovanski, A Kiiskinen, B King, A Kinvig, NJ Kjaer, O Klapp, H Klein, P Kluit, P Kokkinias, M Koratzinos, C Kourkoumelis, V Kostioukhine, O Kouznetsov, M Krammer, E Kriznic, Z Krumstein, P Kubinec, J Kurowska, K Kurvinen, JW Lamsa, DW Lane, P Langefeld, V Lapin, JP Laugier, R Lauhakangas, G Leder, F Ledroit, V Lefeburc, L Leinonen, A Leisos, R Leitner, J Lemonne, G Lenzen, V Lepeltier, T Lesiak, M Lethuiller, J Libby, D Liko, A Lipniacka, I Lippi, B Loerstad, JG Loken, JH Lopes, JM Lopez, R Lopez-Fernandez, D Loukas, P Lutz, L Lyons, J MacNaughton, JR Mahon, A Maio, A Malek, TGH Malmgren, S Maltezos, V Malychev, F Mandl, J Marco, R Marco, B Marechal, M Margoni, JC Marin, C Mariotti, A Markou, C Martinez-Rivero, F Martiniz-Vidal, SMI Garcia, J Masik, N Mastroyiannopoulos, F Matorras, C Matteuzzi, G Matthiae, F Mazzucato, M Mc Cubbin, R Mc Kay, R Mc Nulty, G Mc Pherson, C Meroni, WT Meyer, A Miagkov, E Migliore, L Mirabito, WA Mitaroff, U Mjoernmark, T Moa, M Moch, R Moeller, K Moenig, MR Monge, X Moreau, P Morettini, G Morton, U Mueller, K Muenich, M Mulders, C Mulet-Harquis, R Muresan, WJ Murray, B Muryn, G Myatt, T Myklebust, F Naraghi, M Nassiakou, FL Navarria, S Navas, K Nawrocki, P Negri, S Nemecek, N Neufeld, R Nicolaidou, BS Nielson, P Niezurawski, M Nikolenko, V Nomokonov, A Normand, A Nygren, V Obraztsov, AG Olshevski, A Onofre, R Orava, C Orazi, K Osterberg, A Ouraou, M Paganoni, S Paiano, R Pain, R Paiva, J Palacios, H Palka, TD Papadopoulou, K Papageorgiou, L Pape, C Parkes, F Parodi, C Parzefall, A Passeri, O Passon, M Pegoraro, L Peralta, M Pernicka, A Perrotta, C Petridou, A Petrolini, HT Phillips, F Pierre, M Pimenta, E Piotto, T Podobnik, ME Pol, G Polok, P Poropat, V Pozdniakov, P Privitera, N Pukhaeva, A Pullia, D Radojicic, S Ragazzi, H Rahmani, PN Ratoff, AL Read, P Rebecchi, NG Redaelli, M Regler, D Reid, R Reinhardt, PB Renton, LK Resvanis, F Richard, J Ridky, G Rinaudo, G Rodrigo, O Rohne, A Romero, P Ronchese, EI Rosenberg, P Rosinsky, P Roudeau, T Rovelli, C Royon, V Ruhlmann-Kleider, A Ruiz, H Saarikko, Y Sacquin, A Sadovsky, G Sajot, J Salt, D Sampsonidis, M Sannino, H Schneider, P Schwemling, B Schwering, U Schwickerath, MAE Schyns, F Scuri, P Seager, Y Sedykh, AM Segar, R Sekulin, RC Shellard, A Sheridan, M Siebel, L Simard, F Simonetto, AN Sisakian, G Smadja, N Smirnov, O Smirnova, GR Smith, A Sokolov, A Sopczak, R Sosnowski, T Spassov, E Spiriti, P Sponholz, S Squarcia, C Stanescu, S Stanic, K Stevenson, A Stocchi, J Strauss, R Strub, B Stugu, M Szczekowski, M Szeptycka, T Tabarelli, F Tegenfeldt, F Terranova, J Thomas, J Timmermans, N Tinti, LG Tkatchev, S Todorova, A Tomaradze, B Tome, A Tonazzo, L Tortora, G Transtromer, D Treille, G Tristram, M Trochimezuk, C Troncon, A Tsirou, ML Turluer, IA Tyapkin, S Tzamarias, O Ullaland, V Uvarov, G Valenti, E Vallazza, C Vander Velde, GW Van Apeldoorn, P Van Dam, WK Van Doninck, J Van Eldik, A Van Lysebetten, N Van Remortel, I Van Vulpen, N Vassilopoulos, G Vegni, L Ventura, W Venus, F Verbeure, M Verlato, LS Vertogradov, V Verzi, D Vilanova, L Vitale, E Vlasov, AS Vodopyanov, C Vollmer, G Voulgaris, V Vrba, H Wahlen, C Walck, C Weiser, D Wicke, JH Wickens, GR Wilkinson, M Winter, M Witek, G Wolf, J Yi, O Yushchenko, A Zalewska, P Zalewski, D Zavtranik, E Zevgolatakos, NI Zimin, GC Zucchelli, G Zumerle