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PRODUCTION OF LAMBDA AND LAMBDA(LAMBDA)OVER-BAR CORRELATIONS IN THE HADRONIC DECAYS OF THE Z(0)

PHYSICS LETTERS B 318:1 (1993) 249-262

Authors:

P ABREU, W ADAM, T ADYE, E AGASI, R ALEKSAN, GD ALEKSEEV, A ALGERI, P ALLEN, S ALMEHED, SJ ALVSVAAG, U AMALDI, A ANDREAZZA, P ANTILOGUS, WD APEL, RJ APSIMON, Y ARNOUD, B ASMAN, JE AUGUSTIN, A AUGUSTINUS, P BAILLON, P BAMBADE, F BARAO, R BARATE, G BARBIELLINI, DY BARDIN, GJ BARKER, A BARONCELLI, O BARRING, JA BARRIO, W BARTL, MJ BATES, M BATTAGLIA, M BAUBILLIER, KH BECKS, M BEGALLI, P BEILLIERE, Y BELOKOPYTOV, P BELTRAN, D BENEDIC, AC BENVENUTI, M BERGGREN, D BERTRAND, F BIANCHI, MS BILENKY, P BILLOIR, J BJARNE, D BLOCH, J BLOCKI, S BLYTH, V BOCCI, PN BOGOLUBOV, T BOLOGNESE, M BONESINI, W BONIVENTO, PSL BOOTH, G BORISOV, H BORNER, C BOSIO, B BOSTJANCIC, S BOSWORTH, O BOTNER, E BOUDINOV, B BOUQUET, C BOURDARIOS, TJV BOWCOCK, M BOZZO, S BRAIBANT, P BRANCHINI, KD BRAND, RA BRENNER, H BRIAND, C BRICMAN, L BRILLAULT, RCA BROWN, P BRUCKMAN, JM BRUNET, A BUDZIAK, L BUGGE, T BURAN, H BURMEISTER, JAMA BUYTAERT, M CACCIA, M CALVI, AJC ROZAS, R CAMPION, T CAMPORESI, V CANALE, F CAO, F CARENA, L CARROLL, MVC GIMENEZ, A CATTAI, FR CAVALLO, L CERRITO, V CHABAUD, A CHAN, P CHARPENTIER, L CHAUSSARD, J CHAUVEAU, P CHECCHIA, GA CHELKOV, L CHEVALIER, P CHLIAPNIKOV, V CHOROWICZ, JTM CHRIN, V CINDRO, P COLLINS, JL CONTRERAS, R CONTRI, E CORTINA, G COSME, F COUCHOT, HB CRAWLEY, D CRENNELL, G CROSETTI, JC MAESTRO, S CZELLAR, E DAHLJENSEN, B DALMAGNE, M DAM, G DAMGAARD, G DARBO, E DAUBIE, A DAUM, PD DAUNCEY, M DAVENPORT, J DAVIES, W DASILVA, C DEFOIX, P DELPIERRE, N DEMARIA, A DEANGELIS, H DEBOECK, W DEBOER, S DEBRABANDERE, C DECLERCQ, MDM DEFEZLASO, C DELAVAISSIERE, B DELOTTO, A DEMIN, H DIJKSTRA, L DICIACCIO, J DOLBEAU, M DONSZELMANN, K DOROBA, M DRACOS, J DREES, M DRIS, Y DUFOUR, F DUPONT, D EDSALL, LO EEK, PAM EEROLA, R EHRET, T EKELOF, G EKSPONG, AE PEISERT, M ELSING, JP ENGEL, N ERSHAIDAT, ME SANTO, V FALALEEV, D FASSOULIOTIS, M FEINDT, A FERRER, TA FILIPPAS, A FIRESTONE, H FOETH, E FOKITIS, F FONTANELLI, KAJ FORBES, JL FOUSSET, S FRANCON, B FRANEK, P FRENKIEL, DC FRIES, AG FRODESEN, F FULDAQUENZER, H FURSTENAU, J FUSTER, D GAMBA, C GARCIA, J GARCIA, C GASPAR, U GASPARINI, P GAVILLET, EN GAZIS, JP GERBER, P GIACOMELLI, D GILLESPIE, R GOKIELI, B GOLOB, VM GOLOVATYUK, JJGY CADENAS, G GOPAL, L GORN, M GORSKI, V GRACCO, A GRANT, F GRARD, E GRAZIANI, G GROSDIDIER, E GROSS, B GROSSETETE, S GUMENYUK, J GUY, U HAEDINGER, F HAHN, M HAHN, S HAIDER, Z HAJDUK, A HAKANSSON, A HALLGREN, K HAMACHER, GH DEMONCHENAULT, W HAO, FJ HARRIS, V HEDBERG, T HENKES, R HENRIQUES, JJ HERNANDEZ, P HERQUET, H HERR, TL HESSING, I HIETANEN, CO HIGGINS, E HIGON, HJ HILKE, SD HODGSON, T HOFMOKL, SO HOLMGREN, PJ HOLT, D HOLTHUIZEN, PF HONORE, M HOULDEN, J HRUBEC, K HUET, PO HULTH, K HULTQVIST, P IOANNOU, PS IVERSEN, JN JACKSON, P JALOCHA, G JARLSKOG, P JARRY, B JEANMARIE, EK JOHANSSON, M JONKER, L JONSSON, P JUILLOT, G KALKANIS, G KALMUS, F KAPUSTA, M KARLSSON, E KARVELAS, S KATSANEVAS, EC KATSOUFIS, R KERANEN, BA KHOMENKO, NN KHOVANSKI, B KING, NJ KJAER, H KLEIN, A KLOVNING, P KLUIT, A KOCHMEHRIN, JH KOEHNE, B KOENE, P KOKKINIAS, M KORATZINOS, K KORCYL, AV KORYTOV, V KOSTIOUKHINE, C KOURKOUMELIS, O KOUZNETSOV, PH KRAMER, M KRAMMER, C KREUTER, J KROLIKOWSKI, I KRONKVIST, U KRUENERMARQUIS, W KUCEWICZ, K KULKA, K KURVINEN, C LACASTA, C LAMBROPOULOS, JW LAMSA, L LANCERI, V LAPIN, I LAST, JP LAUGIER, R LAUHAKANGAS, G LEDER, F LEDROIT, R LEITNER, Y LEMOIGNE, J LEMONNE, G LENZEN, V LEPELTIER, T LESIAK, JM LEVY, E LIEB, D LIKO, J LINDGREN, R LINDNER, I LIPPI, B LOERSTAD, M LOKAJICEK, JG LOKEN, A LOPEZFERNANDEZ, MAL AGUERA, M LOS, D LOUKAS, JJ LOZANO, P LUTZ, L LYONS, G MAEHLUM, J MAILLARD, A MAIO, A MALTEZOS, F MANDL, J MARCO, M MARGONI, JC MARIN, A MARKOU, T MARON, S MARTI, C MARTINEZRIVERO, F MATORRAS, C MATTEUZZI, G MATTHIAE, M MAZZUCATO, M MCCUBBIN, R MCKAY, R MCNULTY, J MEDBO, G MEOLA, C MERONI, WT MEYER, M MICHELOTTO, I MIKULEC, L MIRABITO, WA MITAROFF, GV MITSELMAKHER, U MJOERNMARK, T MOA, R MOELLER, K MOENIG, MR MONGE, P MORETTINI, H MUELLER, WJ MURRAY, G MYATT, FL NAVARRIA, P NEGRI, S NEMECEK, R NICOLAIDOU, BS NIELSEN, B NIJJHAR, V NIKOLAENKO, PES NILSEN, P NISS, A NOMEROTSKI, V OBRAZTSOV, AG OLSHEVSKI, R ORAVA, A OSTANKOV, K OSTERBERG, A OURAOU, M PAGANONI, R PAIN, H PALKA, TD PAPADOPOULOU, L PAPE, F PARODI, A PASSERI, M PEGORARO, J PENNANEN, L PERALTA, H PERNEGGER, M PERNICKA, A PERROTTA, C PETRIDOU, A PETROLINI, G PIANA, F PIERRE, M PIMENTA, S PLASZCZYNSKI, O PODOBRIN, ME POL, G POLOK, P POROPAT, V POZDNIAKOV, P PRIVITERA, A PULLIA, D RADOJICIC, S RAGAZZI, H RAHMANI, J RAMES, PN RATOFF, AL READ, P REBECCHI, NG REDAELLI, M REGLER, D REID, PB RENTON, LK RESVANIS, F RICHARD, J RICHARDSON, J RIDKY, G RINAUDO, I RODITI, A ROMERO, I RONCAGLIOLO, P RONCHESE, C RONNQVIST, EI ROSENBERG, E ROSSO, P ROUDEAU, T ROVELLI, W RUCKSTUHL, V RUHLMANNKLEIDER, A RUIZ, H SAARIKKO, Y SACQUIN, G SAJOT, J SALT, J SANCHEZ, M SANNINO, S SCHAEL, H SCHNEIDER, MAE SCHYNS, G SCIOLLA, F SCURI, AM SEGAR, A SEITZ, R SEKULIN, M SESSA, R SEUFERT, RC SHELLARD, I SICCAMA, P SIEGRIST, S SIMONETTI, F SIMONETTO, AN SISAKIAN, G SKJEVLING, G SMADJA, O SMIRNOVA, GR SMITH, R SOSNOWSKI, D SOUZASANTOS, T SPASSOV, E SPIRITI, S SQUARCIA, H STAECK, C STANESCU, S STAPNES, G STAVROPOULOS, F STICHELBAUT, A STOCCHI, J STRAUSS, J STRAVER, R STRUB, B STUGU, M SZCZEKOWSKI, M SZEPTYCKA, P SZYMANSKI, T TABARELLI, O TCHIKILEV, GE THEODOSIOU, A TILQUIN, J TIMMERMANS, VG TIMOFEEV, LG TKATCHEV, T TODOROV, DZ TOET, O TOKER, A TOMARADZE, B TOME, E TORASSA, L TORTORA, D TREILLE, W TRISCHUK, G TRISTRAM, C TRONCON, A TSIROU, EN TSYGANOV, ML TURLUER, T TUUVA, IA TYAPKIN, M TYNDEL, S TZAMARIAS, S UEBERSCHAER, O ULLALAND, V UVAROV, G VALENTI, E VALLAZZA, JAV FERRER, C VANDERVELDE, GW VANAPELDOORN, P VANDAM, M VANDERHEIJDEN, WK VANDONINCK, J VANELDIK, P VAZ, G VEGNI, L VENTURA, W VENUS, F VERBEURE, M VERLATO, LS VERTOGRADOV, D VILANOVA, P VINCENT, L VITALE, E VLASOV, AS VODOPYANOV, M VOLLMER, M VOUTILAINEN, V VRBA, H WAHLEN, C WALCK, F WALDNER, A WEHR, M WEIERSTALL, P WEILHAMMER, AM WETHERELL, JH WICKENS, GR WILKINSON, WSC WILLIAMS, M WINTER, M WITEK, G WORMSER, K WOSCHNAGG, N YAMDAGNI, P YEPES, A ZAITSEV, A ZALEWSKA, P ZALEWSKI, M ZANIN, D ZAVRTANIK, E ZEVGOLATAKOS, NI ZIMIN, M ZITO, D ZONTAR, R ZUBERI, G ZUMERLE, J ZUNIGA
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Observation of hard scattering in photoproduction at HERA

Physics Letters B 297:3-4 (1992) 404-416

Authors:

M Derrick, D Krakauer, S Magill, B Musgrave, J Repond, K Sugano, R Stanek, RL Talaga, J Thron, F Arzarello, R Ayed, G Barbagli, G Bari, M Basile, L Bellagamba, D Boscherini, G Bruni, P Bruni, G Cara Romeo, G Castellini, M Chiarini, L Cifarelli, F Cindolo, F Ciralli, A Contin, S D'Auria, C Del Papa, F Frasconi, P Giusti, G Iacobucci, G Laurenti, G Levi, Q Lin, B Lisowski, G Maccarrone, A Margotti, T Massam, R Nania, C Nemoz, F Palmonari, G Sartorelli, R Timellini, Y Zamora Garcia, A Zichichi, A Bargende, F Barreiro, J Crittenden, H Dabbous, K Desch, B Diekmann, M Geerts, G Geitz, B Gutjahr, H Hartmann, J Hartmann, D Haun, K Heinloth, E Hilger, HP Jakob, S Kramarczyk, M Kückes, A Mass, S Mengel, J Mollen, H Müsch, E Paul, R Schattevoy, B Schneider, JL Schneider, R Wedemeyer, A Cassidy, DG Cussans, N Dyce, HF Fawcett, B Foster, R Gilmore, GP Heath, M Lancaster, TJ Llewellyn, J Malos, CJS Morgado, RJ Tapper, SS Wilson, RR Rau, A Bernstein, A Caldwell, I Gialas, JA Parsons, S Ritz, F Sciulli, PB Straub, L Wai, S Yang, T Barillari, M Schioppa, G Susinno, W Burkot, J Chwastowski, A Dwuraźny, A Eskreys

Abstract:

We report a study of electron proton collisions at very low Q2, corresponding to virtual photoproduction at centre of mass energies in the range 100-295 GeV. The distribution in transverse energy of the observed hadrons is much harder than can be explained by soft processes. Some of the events show back-to-back two-jet production at the rate and with the characteristics expected from hard two-body scattering. A subset of the two-jet events have energy in the electron direction consistent with that expected from the photon remnant in resolved photon processes. © 1992.
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Classification of the hadronic decays of the Z0 into b and c quark pairs using a neural network

Physics Letters B 295:3-4 (1992) 383-395

Authors:

P Abreu, W Adam, T Adye, E Agasi, GD Alekseev, A Algeri, P Allen, S Almehed, SJ Alvsvaag, U Amaldi, EG Anasoontzis, A Andreazza, P Antilogus, WD Apel, RJ Apsimon, B Åsman, JE Augustin, A Augustinus, P Baillon, P Bambade, F Barao, R Barate, G Barbiellini, DY Bardin, G Barker, A Baroncelli, O Barring, JA Barrio, W Bartl, MJ Bates, M Battaglia, M Baubillier, KH Becks, CJ Beeston, M Begalli, P Beilliere, Y Belokopytov, P Beltran, D Benedic, AC Benvenuti, M Berggren, D Bertrand, F Bianchi, MS Bilenky, P Billoir, J Bjarne, D Bloch, S Blyth, V Bocci, PN Bogolubov, T Bolognese, M Bonesini, W Bonivento, PSL Booth, P Borgeaud, G Borisov, H Borner, C Bosio, B Bostjancic, S Bosworth, O Botner, B Bouquet, C Bourdarios, TJV Bowcock, M Bozzo, S Braibant, P Branchini, KD Brand, RA Brenner, H Briand, C Bricman, RCA Brown, N Brummer, JM Brunet, L Bugge, T Buran, H Burmeister, JAMA Buytaert, M Caccia, M Calvi, AJ Camacho Rozas, T Camporesi, V Canale, F Cao, F Carena, L Carroll, C Caso, MV Castillo Gimenez, A Cattai, FR Cavallo, L Cerrito, V Chabaud, A Chan, P Charpentier, L Chaussard, J Chauveau, P Checchia, GA Chelkov, L Chevalier, P Chliapnikov

Abstract:

A classifier based on a feed-forward neural network has been used for separating a sample of about 123 500 selected hadronic decays of the Z0, collected by DELPHI during 1991, into three classes according to the flavour of the original quark pair: uu+dd+ss (unresolved), cc and bb. The classification has been used to compute the partial widths of the Z0 into b and c quark pairs. This gave Γcc/Γh = 0.151 ± 0.008 (stat.) ± 0.041 (syst.), Γbb/Γh = 0.232±0.005 (stat.)±0.017 (syst.). © 1992.
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A study of the decays of tau leptons produced on the Z resonance at LEP

Zeitschrift für Physik C Particles and Fields 55:4 (1992) 555-567

Authors:

P Abreu, W Adam, T Adye, E Agasi, GD Alekseev, P Allen, S Almehed, SJ Alvsvaag, U Amaldi, EG Anassontzis, A Andreazza, P Antilogus, WD Apel, RJ Apsimon, B Åsman, JE Augustin, A Augustinus, P Baillon, P Bambade, F Barao, R Barate, G Barbiellini, DY Bardin, A Baroncelli, O Barring, JA Barrio, W Bartl, MJ Bates, M Battaglia, M Baubillier, KH Becks, CJ Beeston, M Begalli, P Beilliere, Y Belokopytov, P Beltran, D Benedic, M Berggren, D Bertrand, F Bianchi, MS Bilenky, P Billoir, J Bjarne, D Bloch, S Blyth, V Bocci, PN Bogolubov, T Bolognese, M Bonesini, W Bonivento, PSL Booth, P Borgeaud, G Borisov, H Borner, C Bosio, B Bostjancic, S Bosworth, O Botner, B Bouquet, C Bourdarios, TJV Bowcock, M Bozzo, S Braibant, P Branchini, KD Brand, RA Brenner, H Briand, C Bricman, RCA Brown, N Brummer, JM Brunet, L Bugge, T Buran, H Burmeister, JAMA Buytaert, M Caccia, M Calvi, AJ Camacho Rozas, T Camporesi, V Canale, F Cao, F Carena, L Carroll, C Caso, E Castelli, MV Castillo Gimenez, A Cattai, FR Cavallo, L Cerrito, V Chabaud, A Chan, P Charpentier, L Chaussard, J Chauveau, P Checchia, GA Chelkov, L Chevalier, P Chliapnikov, V Chorowicz, JTM Chrin

Abstract:

From the analysis of a data sample corresponding to an integrated luminosity of 4.63 pb-1 taken during the 1990 run of LEP at centre of mass energies between 88.2 GeV an 94.2 GeV, the tau decays {Mathematical expression} and their charge conjugates have been studied. The following branching ratios have been measured; {Mathematical expression}, {Mathematical expression}, Br(τ- → π- (K-)vτ)=11.9±0.7±0.7%, BR (τ- → ρ- vτ)= 22.4±0.8±1.3%, in good agreement with world averages. The measured electronic and muonic branching ratios lead to a measurement of the strong coupling constant, αs (mτ) = 0.26-0.12+0.09. Extrapolating the αs value from mτ to mZ yields αs (mZ) = 0.109-0.028+0.012. The average polarization Pτ of taus produced in Z → τs τs decays has also been measured using the above decay modes. The weighted mean of the polarizations obtained from the four decay modes is Pτ=-0.24±0.07. This value of Pτ gives, in the improved Born approximation, a ratio between the axial and vector coupling constants of the tau of υτ/aτ = 0.12 ± 0.04, and hence a value of the effective electroweak mixing parameter sin2 θW(mZ2). © 1992 Springer-Verlag.
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Measurement of the average lifetime of B hadrons

Zeitschrift für Physik C Particles and Fields 53:4 (1992) 567-580

Authors:

P Abreu, W Adam, F Adami, T Adye, T Akesson, GD Alekseev, P Allen, S Almehed, SJ Alvsvaag, U Amaldi, E Anassontzis, P Antilogus, WD Apel, RJ Apsimon, B Åsman, P Astier, JE Augustin, A Augustinus, P Baillon, P Bambade, F Barao, R Barate, G Barbiellini, DY Bardin, A Baroncelli, O Barring, W Bartl, MJ Bates, M Bataglia, M Baubillier, KH Becks, CJ Beeston, M Begalli, P Beilliere, Y Belokopytov, P Beltran, D Benedic, JM Benlloch, M Berggren, D Bertrand, F Bianchi, MS Bilenky, P Billoir, J Bjarne, D Bloch, S Blyth, V Bocci, PN Bogolubov, T Bolognese, M Bonapart, M Bonesini, W Bonivento, PSL Booth, M Boratav, P Borgeaud, G Borisov, H Borner, C Bosio, B Bostjancic, O Botner, B Bouquet, M Bozzo, S Braibant, P Branchini, KD Brand, RA Brenner, C Bricman, RCA Brown, N Brummer, JM Brunet, L Bugge, T Burran, H Burmeister, JAMA Buytaert, M Caccia, M Calvi, AJ Camacho Rozas, A Campion, T Camporesi, V Canale, F Cao, F Carena, L CArroll, C Caso, E Castelli, MV Castillo Gimenez, A Cattai, FR Cavallo, L Cerrito, A Chan, P Charpentier, P Checchia, GA Chelkov, L Chevalier, M Chliapnikov, V Chorowicz, R Cirio, MP Clara, P Collins, JL Contreras

Abstract:

The average lifetime of B hadrons produced in hadronic Z0 decays has been measured with the DELPHI detector at LEP. The measurement is based on the analysis of the impact parameter distributions of high pt muons and hadrons. The resulting mean B lifetimes are τB=(1.30±0.10±0.08)ps and τB=(1.27±0.04±0.12)ps respectively, giving a combined value of τB=(1.28±0.10)ps. The hadronic sample was also used to measure the partial Z0 width {Mathematical expression} and gave a value of 0.222-0.031+0.033±0.017. © 1992 Springer-Verlag.
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