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Study of charged-current ep interactions at Q2 > 200 GeV2 with the ZEUS detector at HERA

Zeitschrift fur Physik C-Particles and Fields 72:1 (1996) 47-64

Authors:

M Derrick, D Krakauer, S Magill, D Mikunas, B Musgrave, JR Okrasinski, J Repond, R Stanek, RL Talaga, H Zhang, MCK Mattingly, P Antonioli, G Bari, M Basile, L Bellagamba, D Boscherini, A Bruni, G Bruni, P Bruni, G Cara Romeo, G Castellini, L Cifarelli, F Cindolo, A Contin, M Corradi, I Gialas, P Giusti, G Iacobucci, G Laurenti, G Levi, A Margotti, T Massam, R Nania, F Palmonari, A Pesci, A Polini, G Sartorelli, Y Zamora Garcia, A Zichichi, C Amelung, A Bornheim, J Crittenden, R Deffner, T Doeker, M Eckert, L Feld, A Frey, M Geerts, M Grothe, H Hartmann, K Heinloth, L Heinz, E Hilger, HP Jakob, UF Katz, S Mengel, E Paul, M Pfeiffer, C Rembser, D Schramm, J Stamm, R Wedemeyer, S Campbell-Robson, A Cassidy, WN Cottingham, N Dyce, B Foster, S George, ME Hayes, GP Heath, HF Heath, D Piccioni, DG Roff, RJ Tapper, R Yoshida, M Arneodo, R Ayad, M Capua, A Garfagnini, L Iannotti, M Schioppa, G Susinno, A Caldwell, N Cartiglia, Z Jing, W Liu, JA Parsons, S Ritz, F Sciulli, PB Straub, L Wai, S Yang, Q Zhu, P Borzemski, J Chwastowski, A Eskreys, Z Jakubowski, MB Przybycień, M Zachara, L Zawiejski

Abstract:

The cross sections for the deep inelastic charged-current interactions e+p → ν̄X and e-p → νX have been measured in the kinematic region x > 0.006 and Q2 > 200GeV2, using the e+p and e-p data collected with the ZEUS detector during 1993 and 1994. For the integrated cross sections, σe+→ν̄X(Q2>200 GeV2) = 30.3- 4.2+ 5.5 [stat] -2.6+1.6 [syst] pb σe-p→νX(Q2>200 GeV2) = 54.7-9.8+15.9 [stat] -3.4+2.8 [syst] pb are obtained, in good agreement with the Standard Model expectations of 32.3pb and 65.8pb. The differential cross sections have been measured as functions of Q2, x and y. The differences between e+p and e-p scattering, which are expected from the V-A helicity structure of the weak interaction and from the quark content of the proton, are clearly observed. No significant deviation from the Standard Model predictions is found. The measured Q2 dependence of the differential cross sections for e+ and c- induced CC DIS reactions is used to determine the W mass. The measured value of MW is 79 -7 -4+8 +4 GeV, in good agreement with direct measurements performed at pp̄ colliders. A jet analysis has been performed and CC events with multiple jets have been observed. The distributions of the jet transverse momentum and rapidity as well as transverse energy flow jet profiles have been measured and are compared to the script O sign(αs) predictions of the ARIADNE and MEPS Monte Carlo models. Good agreement is observed in both the jet profiles and the jet rates. A search for charged-current events with a large rapidity gap between the observed hadronic system and the outgoing proton system yielded one candidate event in the e+p sample, corresponding to a cross section of σe+p→ν̄X(Q2 > 200 GeV2; ηmax < 2.5) = 0.8 -0.7+1.8 [stat] ±0.1 [syst] pb. © Springer-Verlag 1996.
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Performance of the DELPHI detector

Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 378:1-2 (1996) 57-100

Authors:

P Abreu, W Adam, T Adye, E Agasi, I Ajinenko, R Aleksan, GD Alekseev, R Alemany, PP Allport, S Almehed, SJ Alvsvaag, U Amaldi, S Amato, A Andreazza, ML Andrieux, P Antilogus, WD Apel, Y Arnoud, 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, J Baudot, KH Becks, M Begalli, P Beilliere, Y Belokopytov, AC Benvenuti, M Berggren, D Bertrand, F Bianchi, M Bigi, MS Bilenky, P Billoir, D Bloch, M Blume, S Blyth, T Bolognese, M Bonesini, W Bonivento, PSL Booth, C Bosio, S Bosworth, O Botner, B Bouquet, C Bourdarios, TJV Bowcock, M Bozzo, P Branchini, KD Brand, T Brenke, RA Brenner, C Bricman, L Brillault, RCA Brown, P Bruckman, JM Brunet, L Bugge, T Buran, T Burgsmueller, P Buschmann, A Buys, S Cabrera, M Caccia, M Calvi, AJ Camacho Rozas, T Camporesi, V Canale, M Canepa, K Cankocak, F Cao, F Carena, P Carrilho, L Carroll, C Caso, MV Castillo Gimenez, A Cattai, FR Cavallo, L Cerrito, V Chabaud, P Charpentier, L Chaussard, J Chauveau, P Checchia, GA Chelkov, M Chen, R Chierici, P Chliapnikov

Abstract:

DELPHI (DEtector with Lepton, Photon and Hadron Identification) is a detector for e+e- physics, designed to provide high granularity over a 4π solid angle, allowing an effective particle identification. It has been operating at the LEP (Large Electron-Positron) collider at CERN since 1989. This article reviews its performance.
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Search for the lightest chargino at √s = 130 and 136 GeV

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 382:3 (1996) 323-336

Authors:

P Abreu, W Adam, T Adye, E Agasi, I Ajinenko, R Aleksan, GD Alekseev, R Alemany, PP Allport, S Almehed, U Amaldi, S Amato, A Andreazza, ML Andrieux, P Antilogus, WD Apel, Y Arnoud, B Åsman, JE Augustin, A Augustinus, P Baillon, P Bambade, F Barao, R Barate, M Barbi, DY Bardin, A Baroncelli, O Barring, JA Barrio, W Bartl, MJ Bates, M Battaglia, M Baubillier, J Baudot, KH Becks, M Begalli, P Beilliere, Y Belokopytov, K Belous, AC Benvenuti, M Berggren, D Bertini, D Bertrand, F Bianchi, M Bigi, MS Bilenky, P Billoir, D Bloch, M Blume, T Bolognese, M Bonesini, W Bonivento, PSL Booth, C Bosio, O Botner, E Boudinov, B Bouquet, C Bourdarios, TJV Bowcock, M Bozzo, P Branchini, KD Brand, T Brenke, RA Brenner, C Bricman, RCA Brown, P Bruckman, JM Brunei, L Bugge, T Buran, T Burgsmueller, P Buschmann, A Buys, S Cabrera, M Caccia, M Calvi, AJ Camacho Rozas, T Camporesi, V Canale, M Canepa, K Cankocak, F Cao, F Carena, L Carroll, C Caso, MV Castillo Gimenez, A Cattai, FR Cavallo, V Chabaud, M Chapkin, P Charpentier, L Chaussard, P Checchia, GA Chelkov, M Chen, R Chierici, P Chliapnikov, P Chochula, V Chorowicz, V Cindro

Abstract:

A search for pair production of the lightest chargino at √s = 130.4 and 136.3 GeV has been carried out using the data sample corresponding to the 5.92 pb-1 recorded by the DELPHI detector during the high energy run of LEP in the last period of 1995. The theoretical reference model has been the Minimal Supersymmetric Standard Model with R-parity conservation. The three topologies expected for the decay of a pair of charginos, namely two acoplanar leptons plus missing energy (ℓℓ), two jets and an isolated lepton plus missing energy (jjℓ) and missing energy in a hadronic environment (√s), were investigated. No evidence of a signal was found. Lower mass limits were derived for various scenarios, including the case of a low mass difference between the chargino and the neutralino and of a light sneutrino. The mass limits range between 56.3 GeV/c2 and the kinematic limit.
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Search for anomalous production of single photons at √s = 130 and 136 GeV

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 380:3-4 (1996) 471-479

Authors:

W Adam, T Adye, E Agasi, I Ajinenko, R Aleksan, GD Alekseev, R Alemany, PP Allport, S Almehed, U Amaldi, S Amato, A Andreazza, ML Andrieux, P Antilogus, WD Apel, Y Arnoud, B Åsman, JE Augustin, A Augustinus, P Baillon, P Bambade, F Barao, R Barate, M Barbi, G Barbiellini, DY Bardin, A Baroncelli, O Barring, JA Barrio, W Bartl, MJ Bates, M Battaglia, M Baubillier, J Baudot, KH Becks, M Begalli, P Beilliere, Y Belokopytov, K Belous, AC Benvenuti, M Berggren, D Bertini, D Bertrand, F Bianchi, M Bigi, MS Bilenky, P Billoir, D Bloch, M Blume, T Bolognese, M Bonesini, W Bonivento, PSL Booth, C Bosio, O Botner, E Boudinov, B Bouquet, C Bourdarios, TJV Bowcock, M Bozzo, P Branchini, KD Brand, T Brenke, RA Brenner, C Bricman, RCA Brown, P Bruckman, JM Brunei, L Bugge, T Buran, T Burgsmueller, P Buschmann, A Buys, S Cabrera, M Caccia, M Calvi, AJ Camacho Rozas, T Camoporesi, V Canale, M Canepa, K Cankocak, F Cao, F Carena, L Carroll, C Caso, MV Castillo Gimenez, A Cattai, FR Cavallo, V Chabaud, P Charpentier, L Chaussard, J Chauveau, P Checchia, GA Chelkov, M Chen, R Chierici, P Chliapnikov, P Chochula, V Chorowicz, V Cindro

Abstract:

This letter reports the results of the measurement of single photon production in the reaction e+e- → γ+ invisible particles at centre-of-mass energies √s = 130 and 136 GeV and an integrated luminosity of 5.83 pb-1, collected with the DELPHI detector at LEP. The signal is compatible with the prediction of the Standard Model for the process e+e- → vv̄γ, and the number of neutrino families has been determined to be Nv, = 3.1 ± 0.6. Limits have been derived on anomalous neutral gauge boson couplings and on compositeness in the framework of a specific model.
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Study of radiative leptonic events with hard photons and search for excited charged leptons at √s = 130-136 GeV DELPHI collaboration

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 380:3-4 (1996) 480-490

Authors:

P Abreu, W Adam, T Adye, E Agasi, I Ajinenko, R Aleksan, GD Alekseev, R Alemany, PP Allport, S Almehed, U Amaldi, S Amato, A Andreazza, ML Andrieux, P Antilogus, WD Apel, Y Arnoud, B Åsman, JE Augustin, A Augustinus, P Baillon, P Bambade, F Barao, R Barate, M Barbi, G Barbiellini, DY Bardin, A Baroncelli, O Barring, JA Barrio, W Bartl, MJ Bates, M Battaglia, M Baubillier, J Baudot, KH Becks, M Begalli, P Beilliere, Y Belokopytov, AC Benvenuti, M Berggren, D Bertini, D Bertrand, F Bianchi, M Bigi, MS Bilenky, P Billoir, D Bloch, M Blume, T Bolognese, M Bonesini, W Bonivento, PSL Booth, C Bosio, O Botner, E Boudinov, B Bouquet, C Bourdarios, TJV Bowcock, M Bozzo, P Branchini, KD Brand, T Brenke, RA Brenner, C Bricman, RCA Brown, P Bruckman, JM Brunet, L Bugge, T Buran, T Burgsmueller, P Buschmann, A Buys, S Cabrera, M Caccia, M Calvi, AJ Camacho Rozas, T Camporcsi, V Canale, M Canepa, K Cankocak, F Cao, F Carena, L Carroll, C Caso, MV Castillo Gimenez, A Cattai, FR Cavallo, V Chabaud, P Charpentier, L Chaussard, J Chauveau, P Checchia, GA Chelkov, M Chen, R Chierici, P Chliapnikov, P Chochula, V Chorowicz, V Cindro

Abstract:

During the last 1995 data acquisition period at LEP, the DELPHI experiment collected an integrated luminosity of 5.9 pb-1 at centre-of-mass energies of 130 GeV and 136 GeV. Radiative leptonic events (e, μ, τ) with high energy photons were studied and compared to Standard Model predictions. The data were used to search for charged excited leptons decaying through an electromagnetic transition. No significant signal was found. From the search for pair produced excited leptons, the limits me* > 62.5 GeV/c2, mμ* > 62.6 GeV/c2 and mτ* > 62.2 GeV/c2 at 95% confidence level were established. For single excited lepton production, upper limits on the ratio λ/mℓ* of the coupling of the excited charged lepton to its mass were derived.
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