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Study of final state photons in hadronic Z0 decay and limits on new phenomena

Zeitschrift für Physik C Particles and Fields 53:4 (1992) 555-565

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 Battaglia, 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 Buran, 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, M Chapkin, P Charpentier, P Checchia, GA Chelkov, L Chevalier, P Chliapnikov, V Chorowicz, R Cirio, MP Clara, P Collins

Abstract:

The differential cross section for final state radiation from primary quarks is obtained from a study of isolated energetic photons produced in the reaction e+e-→Z0→hadrons+γ, as measured in the DELPHI detector at the CERN LEP collider. When combined with the measurement of the total hadronic width of the Z0, the observed rate determines the electroweak coupling constants of up and down type quarks, i.e., {Mathematical expression} No evidence is seen for additional photon production from anomalous decays of the Z0 or from decays of new particles. This measurement leads to upper limits on the production cross section times branching fraction of (a) the Higgs boson in the reaction e+e-→Z0→H +γ, H→hadrons, (b) an excited quark, q*→q+γ, and (c) the contribution of an anomalous decay of the Z0 into a photon and hadrons. These limits, all at the 95% confidence level, vary from 3 to 10pb as the mass of the intermediate state (H, q* or Z*) varies from 10 GeV/c2 to 80 GeV/c2. © 1992 Springer-Verlag.
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A measurement of σtot(γp) at S = 210 GeV

Physics Letters B 293:3-4 (1992) 465-477

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, GC 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:

The total photoproduction cross section is determined from a measurement of electroproduction with the ZEUS detector at HERA. The Q2 values of the virtual photons are in the range 10-7
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Measurement of the Z0 branching fraction to b quark pairs using the boosted sphericity product

Physics Letters B 281:3-4 (1992) 383-393

Authors:

P Abreu, W Adam, F Adami, T Adye, T Akesson, GD Alekseev, P Allen, S Almehed, SJ Alvsvaag, U Amaldi, EG Anassontzis, 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, W Bartl, MJ Bates, M Battaglia, 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 Billior, 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, 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, C L., C Caso, E Castelli, MV Castillo Gimenez, A Cattai, FR Cavallo, L Cerrito, A Chan, M Chapkin, P Charpentier, L Chaussard, J Chauveau, P Checchia, GA Chelkov, L Chevalier, P Chliapnikov, V Chorowicz, R Cirio, MP Clara

Abstract:

From a sample of about 120 000 hadronic Z0 decays, using a technique based on a separation of the different event categories in the boosted sphericity product, the fraction of bb decays has been measured to be 0.219 ± 0.014 (stat)± 0.019 (syst). Using the DELPHI determination of the hadronic Z0 width, this corresponds to a partial width τbb = 378 ± 42 MeV (in good agreement with the standard model prediction of ∼-380 MeV). Combining this measurement with the determinations based on events with high pt leptons gives an estimate for the branching ratio of b into leptons at LEP of (11.2 ± 1.2)%, consistent with previous determinations. © 1992.
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THE DESIGN, STATUS AND PERFORMANCE OF THE ZEUS CENTRAL TRACKING DETECTOR ELECTRONICS

NUCL INSTRUM METH A 315:1-3 (1992) 397-403

Authors:

DG CUSSANS, HF FAWCETT, B FOSTER, RS GILMORE, GP HEATH, TJ LLEWELLYN, J MALOS, CJS MORGADO, RJ TAPPER, DM GINGRICH, N HARNEW, P HALLAMBAKER, J NASH, T KHATRI, PD SHIELD, I MCARTHUR, S TOPPJORGENSEN, FF WILSON, D ALLEN, SA BAIRD, R CARTER, S GALAGADERA, MD GIBSON, RS HATLEY, M JEFFS, R MILBORROW, M MORISSEY, SPH QUINTON, DJ WHITE, J LANE, G NIXON, M POSTRANECKY, AK JAMDAGNI, C MARCOU, DB MILLER, L TOUDUP
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Charged particle multiplicity distributions for fixed number of jets in Z0 hadronic decays

Zeitschrift für Physik C Particles and Fields 56:1 (1992) 63-75

Authors:

P Abreu, W Adam, T Adye, E Agasi, GD Aleseev, 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 Berrgren, 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:

The multiplicity distributions of charged particles in full phase space and in restricted rapidity intervals for events with a fixed number of jets measured by the DELPHI detector are presented. The data are well reproduced by the Lund Parton Shower model and can also be well described by fitted negative binomial distributions. The properties of these distributions in terms of the clan model are discussed. In symmetric 3-jet events the candidate gluon jet is found not to be significantly different in average multiplicity than the mean of the other two jets, thus supporting previous results of the HRS and OPAL experiments. Similar results hold for events generated according to the LUND PS and to the HERWIG models, when the jets are defined by the JADE jet finding algorithm. The method seems to be insensitive for measuring the color charge ratio between gluons and quarks. © 1992 Springer-Verlag.
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