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Search for selectron and squark production in e+p collisions at HERA

Physics Letters Section B Nuclear Elementary Particle and High Energy Physics 434:1-2 (1998) 214-230

Authors:

J Breitweg, M Derrick, D Krakauer, S Magill, D Mikunas, B Musgrave, J Repond, R Stanek, RL Talaga, R Yoshida, H Zhang, MCK Mattingly, F Anselmo, P Antonioli, G Bari, M Basile, L Bellagamba, D Boscherini, A Bruni, G Bruni, G Cara Romeo, G Castellini, L Cifarelli, F Cindolo, A Contin, N Coppola, M Corradi, S de Pasquale, 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, I Brock, K Coböken, J Crittenden, R Deffner, M Eckert, M Grothe, H Hartmann, K Heinloth, L Heinz, E Hilger, HP Jakob, A Kappes, UF Katz, R Kerger, E Paul, M Pfeiffer, J Stamm, H Wieber, DS Bailey, S Campbell-Robson, WN Cottingham, B Foster, R Hall-Wilton, GP Heath, HF Heath, JD McFall, D Piccioni, DG Roff, RJ Tapper, M Capua, L Iannotti, M Schioppa, G Susinno, JY Kim, JH Lee, IT Lim, MY Pac, A Caldwell, N Cartiglia, Z Jing, W Liu, B Mellado, JA Parsons, S Ritz, S Sampson, F Sciulli, PB Straub, Q Zhu, P Borzemski, J Chwastowski, A Eskreys, J Figiel, K Klimek, MB Przybycień, L Zawiejski, L Adamczyk, B Bednarek

Abstract:

We have searched for the production of a selectron and a squark in e+p collisions at a center-of-mass energy of 300 GeV using the ZEUS detector at HERA. The selectron and squark are sought in the direct decay into the lightest neutralino in the framework of supersymmetric extensions to the Standard Model which conserve R-parity. No evidence for the production of supersymmetric particles has been found in a data sample corresponding to 46.6 pb-1 of integrated luminosity. We express upper limits on the product of the cross section times the decay branching ratios as excluded regions in the parameter space of the Minimal Supersymmetric Standard Model. © 1998 Elsevier Science B.V. All rights reserved.
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Measurement of the e+e- → γγ(γ) cross section at the LEP energies

Physics Letters Section B Nuclear Elementary Particle and High Energy Physics 433:3-4 (1998) 429-440

Authors:

P Abreu, W Adam, T Adye, P Adzic, GD Alekseev, R Alemany, PP Allport, S Almehed, U Amaldi, S Amato, P Andersson, A Andreazza, P Antilogus, WD Apel, Y Arnoud, B Asman, JE Augustin, A Augustinus, P Baillon, P Bambade, F Barao, R Barbier, DY Bardin, G Barker, A Baroncelli, O Barring, M Battaglia, M Baubillier, KH Becks, M Begalli, P Beilliere, Y Belokopytov, K Belous, AC Benvenuti, C Berat, M Berggren, D Bertini, D Bertrand, M Besancon, F Bianchi, M Bigi, MS Bilenky, MA Bizouard, D Bloch, M Bonesini, W Bonivento, 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, P Buschmann, S Cabrera, M Caccia, M Calvi, AJ Camacho Rozas, T Camporesi, V Canale, M Canepa, F Carena, L Carroll, C Caso, MV Castillo Gimenez, A Cattai, FR Cavallo, C Cerruti, V Chabaud, M Chapkin, P Charpentier, L Chaussard, P Checchia, GA Chelkov, M Chen, R Chierici, P Chliapnikov, P Chochula, V Chorowicz, J Chudoba, P Collins, M Colomer, R Contri, E Cortina, G Cosme, F Cossutti

Abstract:

The total and the differential cross-sections for the reaction e+e- → γγ(γ) have been measured with the DELPHI detector at LEP at centre-of-mass energies from 130 to 183 GeV for an integrated luminosity of 78.19 pb-1. The results agree with the QED predictions. The lower limits (obtained including previously published results at the Z0 energies) on the QED cutoff parameters are Λ+ > 253 GeV and Λ-> 225 GeV and the lower bound on the mass of an excited electron with an effective coupling constant λγ = 1 is 231 GeV/c2. All the limits are at the 95% confidence level. © 1998 Published by Elsevier Science B.V. All rights reserved.
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A study of the hadronic resonance structure in the decay τ → 3πντ

Physics Letters Section B Nuclear Elementary Particle and High Energy Physics 426:3-4 (1998) 411-427

Authors:

P Abreu, W Adam, T Adye, P Adzic, GD Alekseev, R Alemany, PP Allport, S Almehed, U Amaldi, S Amato, P Andersson, A Andreazza, P Antilogus, WD Apel, Y Arnoud, B Asman, JE Augustin, A Augustinus, P Baillon, P Bambade, F Barao, G Barbiellini, R Barbier, DY Bardin, G Barker, A Baroncelli, O Barring, MJ Bates, M Battaglia, M Baubillier, KH Becks, M Begalli, P Beilliere, Y Belokopytov, K Belous, AC Benvenuti, C Berat, M Berggren, D Bertini, D Bertrand, M Besancon, F Bianchi, M Bigi, MS Bilenky, MA Bizouard, D Bloch, M Bonesini, W Bonivento, 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, KD Brand, T Brenke, RA Brenner, R Brown, P Bruckman, JM Brunet, L Bugge, T Buran, T Burgsmueller, P Buschmann, S Cabrera, M Caccia, M Calvi, AJ Camacho Rozas, T Camporesi, V Canale, M Canepa, F Carena, L Carroll, C Caso, MV Castillo Gimenez, A Cattai, FR Cavallo, C Cerruti, V Chabaud, M Chapkin, P Charpentier, L Chaussard, P Checchia, GA Chelkov, M Chen, R Chierici, P Chliapnikov, P Chochula, V Chorowicz, J Chudoba, K Cieslik, P Collins

Abstract:

The hadronic structure of the decay of the τ lepton to three charged particles, τ → 3πντ, is studied using data collected by the DELPHI detector at LEP between 1992 and 1995. The invariant mass of the 3π system, m3π, is fitted using the models of Kühn and Santamaria, Isgur Morningstar and Reader, and Feindt. The 3π and π+π- mass spectra are compared with each model. Below m23π = 2.3 GeV2, all are in good qualitative agreement. Above m23π = 2.3 GeV2, anomalous behaviour is observed, consistent with the existence of a hitherto unseen decay mode of the τ through a radial excitation of the a1 meson. © 1998 Published by Elsevier Science B.V. All rights reserved.
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The physics performance of LHCb

NUCL INSTRUM METH A 408:1 (1998) 137-145

Authors:

N Harnew, LHCb Collaboration

Abstract:

The LHCb experiment is based on a single arm forward spectrometer optimized to study CP violation in the B system at the LHC. The experiment includes a dedicated trigger system, particle identification and a precise vertex determination; recent developments in these areas will be summarized. The detector will provide precise measurements of all angles of the unitarity triangle, the length of one of the sides (via B-s(0) - (B) over bar(s)(0) mixing) and the height of the triangle. The physics performance for selected channels will be reviewed. (C) 1998 Elsevier Science B.V. All rights reserved.
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First evidence for a charm radial excitation, D

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 426:1-2 (1998) 231-242

Authors:

P Abreu, W Adam, T Adye, P Adzic, I Ajinenko, GD Alekseev, R Alemany, PP Allport, S Almehed, U Amaldi, S Amato, P Andersson, A Andreazza, 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, O Barring, M Battaglia, M Baubillier, KH Becks, M Begalli, P Beilliere, Y Belokopytov, AC Benvenuti, C Berat, M Berggren, D Bertini, D Bertrand, M Besancon, F Bianchi, M Bigi, MS Bilenky, MA Bizouard, D Bloch, M Bonesini, W Bonivento, 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, KD Brand, T Brenke, RA Brenner, R Brown, P Bruckman, JM Brunet, L Bugge, T Buran, T Burgsmueller, P Buschmann, S Cabrera, M Caccia, M Calvi, AJ Camacho Rozas, T Camporesi, V Canale, M Canepa, F Carena, L Carroll, C Caso, MV Castillo Gimenez, A Cattai, FR Cavallo, C Cerruti, V Chabaud, P Charpentier, L Chaussard, P Checchia, GA Chelkov, M Chen, R Chierici, P Chliapnikov, P Chochula, V Chorowicz, J Chudoba, P Collins, M Colomer, R Contri, E Cortina

Abstract:

Using D *+ mesons exclusively reconstructed in the DELPHI detector at LEP, an excess of 66 ± 14(stat.) events is observed in the D *+π+ π- final state with a mass of 2637 ± 2(stat.) ± 6(syst.) MeV/c2 and a full width smaller than 15 MeV/c2 (95% C.L.). This signal is compatible with the expected decay of a radially excited D *′ (JP = 1-) meson. © 1998 Published by Elsevier Science B.V. All rights reserved.
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