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Search for the Standard Model Higgs boson at LEP in the year 2000

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 499:1-2 (2001) 23-37

Authors:

P Goncalves, I Gonzalez Caballero, G Gopal, L Gorn, Y Gouz, V Gracco, J Grahl, E Graziani, G Grosdidier, K Grzelak, J Guy, C Haag, F Hahn, S Hahn, S Haider, A Hallgren, K Hamacher, J Hansen, FJ Harris, S Haug, F Hauler, V Hedberg, S Heising, JJ Hernandez, P Herquet, H Herr, O Hertz, E Higon, SO Holmgren, PJ Holt, S Hoorelbeke, M Houlden, J Hrubec, GJ Hughes, K Hultqvist, JN Jackson, R Jacobsson, P Jalocha, C Jarlskog, G Jarlskog, P Jarry, B Jean-Marie, D Jeans, EK Johansson, P Jonsson, C Joram, P Juillot, L Jungermann, F Kapusta, K Karafasoulis, S Katsanevas, EC Katsoufis, R Keranen, G Kernel, BP Kersevan, BA Khomenko, NN Khovanski, A Kiiskinen, B King, A Kinvig, NJ Kjaer, O Klapp, P Kluit, P Kokkinias, V Kostioukhine, C Kourkoumelis, O Kouznetsov, M Krammer, E Kriznic, Z Krumstein, P Kubinec, M Kucharczyk, J Kurowska, JW Lamsa, JP Laugier, G Leder, F Ledroit, L Leinonen, A Leisos, R Leitner, G Lenzen, V Lepeltier, T Lesiak, M Lethuillier, J Libby, W Liebig, D Liko, A Lipniacka, I Lippi, JG Loken, JH Lopes, JM Lopez, R Lopez-Fernandez, D Loukas, P Lutz, L Lyons, J MacNaughton, JR Mahon, A Maio, A Malek

Abstract:

Searches for the Standard Model Higgs boson have been performed in the data collected by the DELPHI experiment at LEP in the year 2000 at centre-of-mass energies between 200 and 209 GeV corresponding to a total integrated luminosity of 224 pb-1. No evidence for a Higgs signal is observed in the kinematically accessible mass range, and a 95% CL lower mass limit of 114.3 GeV/c2 is set, to be compared with an expected median limit of 113.5 GeV/c2 for these data. © 2001 Elsevier Science B.V.
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Measurement of the ZZ cross-section in e+e- interactions at 183-189 GeV

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 497:3-4 (2001) 199-213

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, 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, P Beilliere, Y Belokopytov, NC Benekos, AC Benvenuti, C Berat, M Berggren, L Berntzon, D Bertrand, M Besancon, MS Bilenky, MA Bizouard, D Bloch, HM Blom, 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, T Buran, 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, 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:

Measurements of on-shell ZZ production are described, using data collected by DELPHI in 1997 and 1998, at centre-of-mass energies √s = 182.6 GeV and 188.6 GeV, respectively. Results obtained in each of the final states qq̄qq̄, μ+μ-qq̄, e+e-qq̄, vv̄qq̄ l+l-l+l-, and vv̄l+l- are presented. The measured cross-sections for on-shell ZZ production via the tree-level doubly-resonant graphs (NC02) are: σNC02 (182.6 GeV) = 0.38 ± 0.18 (stat) ± 0.04 (syst) pb, σNC02 (188.6 GeV) = 0.60±0.13 (stat) ±0.07 (syst) pb. They are consistent with the Standard Model expectations of 0.25 and 0.65 pb at each energy. © 2001 Elsevier Science B.V.
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A measurement of the Tau topological branching ratios

European Physical Journal C 20:4 (2001) 617-637

Authors:

P Abreu, W Adam, T Adye, P Adzic, Z Albrecht, T Alderweireld, GD Alekseev, R Alemany, T Allmendinger, PP Allport, S Almehed, U Amaldi, N Amapane, S Amato, E Anashkin, 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, T Bellunato, Y Belokopytov, K Belous, NC Benekos, AC Benvenuti, C Berat, M Berggren, L Berntzon, D Bertrand, M Besancon, N Besson, MS Bilenky, D Bloch, HM Blom, J Bol, M Bonesini, M Boonekamp, PSL Booth, G Borisov, C Bosio, O Botner, E Boudinov, B Bouquet, TJV Bowcock, I Boyko, I Bozovic, M Bozzo, M Bracko, P Branchini, RA Brenner, E Brodet, P Bruckman, JM Brunet, L Bugge, P Buschmann, M Caccia, M Calvi, T Camporesi, V Canale, F Carena, L Carroll, C Caso, A Cattai, FR Cavallo, M Chapkin, P Charpentier, P Checchia, GA Chelkov, R Chierici, P Chliapnikov, P Chochula, V Chorowicz, J Chudoba, SH Chung, K Cieslik, P Collins, R Contri, G Cosme, F Cossutti, M Costa

Abstract:

Using data collected in the DELPHI detector at LEP-1, measurements of the inclusive τ branching ratios for decay modes containing one, three, or five charged particles have been performed, giving the following results: B1 ≡ B(τ- → (particle)-≥0π0≥0K0 vτ(v̄)) = (85.316 ± 0.093 ± 0.049)%; B3 ≡ B(τ- → 2h-h+≥0π0≥0K0vτ) = (14.569 ± 0.093 ± 0.048)%; B5 ≡ B(τ- → 3h-2h+≥0π0≥0K0vτ) = (0.115 ± 0.013 ± 0.006)%, where h is either a charged π or K meson. The first quoted uncertainties are statistical and the second systematic.
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Measurement of the semileptonic b branching fractions and average b mixing parameter in Z decays

European Physical Journal C 20:3 (2001) 455-478

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 Asman, 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, P Beilliere, Y Belokopytov, NC Benekos, AC Benvenuti, C Berat, M Berggren, L Berntzon, D Bertrand, M Besancon, MS Bilenky, MA Bizouard, D Bloch, HM Blom, 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, 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, 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

Abstract:

The semileptonic branching fractions for primary and cascade b decays BR(b → l-), BR(b → c → l+) and BR(b → c̄ → l- were measured in hadronic Z decays collected by the DELPHI experiment at LEP. The sample was enriched in b decays using the lifetime information and various techniques were used to separate leptons from direct or cascade b decays. By fitting the momentum spectra of di-leptons in opposite jets, the average b mixing parameter x̄ was also extracted. The following results have been obtained: (equation presented).
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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 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

Abstract:

The performance of a prototype Ring Imaging Cherenkov Detector is studied using a charged particle beam. The detector performance, using CF4 and air as radiators, is described. Cherenkov angle precision and photoelectron yield using hybrid photo-diodes and multi-anode PMTs agree with simulations and are assessed in terms of the requirements of the LHCb experiment.
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