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Photon pair production by e+e- annihilation and search for supersymmetric photinos at energies greater than 40 GeV

Zeitschrift Fur Physik C Particles and Fields 26:3 (1984) 337-342

Authors:

M Althoff, W Braunschweig, FJ Kirschfink, K Lübelsmeyer, HU Martyn, R Rosskamp, D Schmitz, H Siebke, W Wallraff, J Eisenmann, HM Fischer, H Hartmann, A Jocksch, G Knop, H Kolanoski, H Kück, V Mertens, R Wedemeyer, B Foster, A Eskreys, K Gather, H Hultschig, P Joos, U Kötz, H Kowalski, A Ladage, B Löhr, D Lüke, P Mättig, D Notz, RJ Nowak, J Pyrlik, M Rushton, W Schütte, D Trines, T Tymieniecka, G Wolf, G Yekutieli, C Xiao, R Fohrmann, E Hilger, T Kracht, HL Krasemann, P Leu, E Lohrmann, D Pandoulas, G Poelz, KU Pösnecker, BH Wiik, R Beuselinck, DM Binnie, PJ Dornan, DA Garbutt, C Jenkins, TD Jones, WG Jones, J McCardle, JK Sedgbeer, J Thomas, WAT Wan Abdullah, KW Bell, MG Bowler, P Bull, RJ Cashmore, PEL Clarke, P Dauncey, R Devenish, P Grossmann, CM Hawkes, SL Lloyd, DJ Mellor, C Youngman, GE Forden, JC Hart, J Harvey, DK Hasell, DH Saxon, F Barreiro, S Brandt, M Dittmar, M Holder, G Kreutz, B Neumann, E Duchovni, Y Eisenberg, U Karshon, G Mikenberg, R Mir, D Revel, E Ronat, A Shapira, M Winik, G Baranko, A Caldwell, M Cherney, JM Izen, M Mermikides, S Ritz, G Rudolph, D Strom

Abstract:

The cross section for the process e+e-→γγ has been measured for c.m. energies 39.5+>61 GeV and Λ+> GeV (95% confidence level) have been determined. A search for two photon final states with missing energy provided lower limits on the masses of the photino and selectron. © 1984 Springer-Verlag.
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Observation of the reaction γγ → ppπ+π-

Physics Letters B 142:1-2 (1984) 135-140

Authors:

M Althoff, W Braunschweig, FJ Kirschfink, K Lübelsmeyer, HU Martyn, J Rimkus, P Rosskamp, HG Sander, D Schmitz, H Siebke, W Wallraff, HM Fischer, H Hartmann, A Jocksch, G Knop, L Köpke, H Kolanoski, H Kück, V Mertens, R Wedemeyer, M Wollstadt, Y Eisenberg, A Eskreys, K Gather, H Hultschig, P Joos, U Kötz, H Kowalski, A Ladage, B Löhr, D Lüke, P Mättig, D Notz, RJ Nowak, J Pyrlik, M Rushton, W Schütte, D Trines, T Tymieniecka, G Wolf, C Xiao, R Fohrmann, E Hilger, T Kracht, HL Krasemann, P Leu, E Lohrmann, D Pandoulas, G Poelz, KU Pösnecker, BH Wiik, R Beuselinck, DM Binnie, AJ Campbell, PJ Dornan, B Foster, DA Garbutt, C Jenkins, TD Jones, WG Jones, J McCardle, JK Sedgbeer, J Thomas, WAT Wan Abdullah, KW Bell, MG Bowler, P Bull, RJ Cashmore, PEL Clarke, R Devenish, P Grossmann, CM Hawkes, SL Lloyd, GL Salmon, C Youngman, GE Forden, JC Hart, J Harvey, DK Hasell, J Proudfoot, DH Saxon, F Barreiro, M Dittmar, M Holder, G Kreutz, B Neumann, E Duchovni, U Karshon, G Mikenberg, R Mir, D Revel, E Ronat, A Shapira, G Yekutieli, G Baranko, T Barklow, A Caldwell, M Cherney, JM Izen, M Mermikides

Abstract:

Production of the ppπ+π- final state by two-photon scattering was observed. The cross section for γγ→ppπ+π- was determined assuming phase space production. No evidence was found for the production or formation of resonances. Upper limits are given for Λ and Δ pair production, for production of ppρ{variant}0 and for the two-photon excitation of cc bound states. © 1984.
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Determination of the τ lifetime in high energy e+e- annihilations

Physics Letters B 141:3-4 (1984) 264-270

Authors:

M Althof, W Braunschweig, FJ Kirschfink, K Lübelsmeyer, HU Martyn, J Rimkus, P Rosskamp, HG Sander, D Schmitz, H Siebke, W Wallraff, HM Fischer, H Hartmann, A Jocksch, G Knop, L Köpke, H Kolanoski, H Kück, V Mertens, R Wedemeyer, M Wollstadt, Y Eisenberg, A Eskreys, K Gather, M Hildebrandt, H Hultschig, P Joos, U Kötz, H Kowalski, A Ladage, B Löhr, D Lüke, P Mättig, D Notz, RJ Nowak, J Pyrlik, M Rushton, W Schütte, D Trines, T Tymieniecka, G Wolf, C Xiao, R Fohrmann, E Hilger, T Kracht, HL Krasemann, P Leu, E Lohrmann, D Pandoulas, G Poelz, KU Pösnecker, BH Wiik, R Beuselinck, DM Binnie, AJ Campbell, P Dornan, B Foster, DA Garbutt, C Jenkins, TD Jones, WG Jones, J McCardle, JK Sedgbeer, J Thomas, WAT Wan Abdullah, KW Bell, MG Bowler, P Bull, RJ Cashmore, PEL Clarke, R Devenish, P Grossmann, CM Hawkes, SL Lloyd, GL Salmon, C Youngman, GE Forden, JC Hart, J Harvey, DK Hasell, J Proudfoot, DH Saxon, F Barreiro, S Brandt, M Dittmar, M Holder, G Kreutz, B Neumann, E Duchovni, U Karshon, G Mikenberg, R Mir, D Revel, E Ronat, A Shapira, G Yekutieli, G Baranko, T Barklow, A Caldwell, M Cherney

Abstract:

We have determined the τ lifetime in e+e- annihilations at an average centre of mass energy of 42.5 GeV, using a pressurized drift chamber close to the interaction point. We find the lifetime to be (3.18-0.75+0.59 ± 0.56) × 10-13 s. The charged weak τ coupling constant relative to that of the μ is found to be Gτ/Gμ = 0.94-0.09+0.12 ± 0.09, in good agreement lepton universality. © 1984.
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Upper limits on the production rate of the decuplet baryons Δ and Σ* in e+e- annihilation at 34.4 GeV

Zeitschrift Fur Physik C Particles and Fields 26:2 (1984) 181-190

Authors:

M Althoff, W Braunschweig, FJ Kirschfink, K Lübelsmeyer, HU Martyn, P Rosskamp, HG Sander, D Schmitz, H Siebke, W Wallraff, J Eisenmann, HM Fischer, H Hartmann, A Jocksch, G Knop, L Köpke, H Kolanoski, H Kück, V Mertens, R Wedemeyer, A Eskreys, K Gather, H Hultschig, P Joos, U Kötz, H Kowalski, A Ladage, B Löhr, D Lüke, P Mättig, KH Mess, D Notz, RJ Nowak, J Pyrlik, R Riethmüller, M Rushton, W Scütte, D Trines, T Tymieniecka, G Wolf, C Xiao, G Yekutieli, R Fohrmann, E Hilger, T Kracht, HL Krasemann, P Leu, E Lohrmann, D Pandoulas, G Poelz, KU Pösnecker, P Schmüser, BH Wiik, R Beuselinck, DM Binnie, AJ Campbell, PJ Dorman, B Foster, DA Garbutt, C Jenkins, TD Jones, WG Jones, J McCardle, JK Sedgbeer, J Thomas, WATW Abdullah, KW Bell, MG Bowler, P Bull, RJ Cashmore, PEL Clarke, R Devenish, P Grossmann, CM Hawkes, SL Lloyd, C Youngman, GE Forden, JC Hart, J Harvey, DK Hasell, DH Saxon, PL Woodworth, F Barreiro, S Brandt, M Dittmar, M Holder, G Kreutz, B Neumann, E Duchovni, Y Eisenberg, U Karshon, G Mikenberg, R Mir, D Revel, E Ronat, A Shapira, M Winik, G Baranko, A Caldwell, M Cherney

Abstract:

Samples of ∼1,900 identified protons and ∼500 Λ have been used to search for decuplet baryon production in e+e- annihilation at a c.m. energy of 34.4 GeV. The p π+ and Λ π± invariant mass spectra contain no Δ or Σ* signals. Upper limits, at 95% confidence level, are that less than 12% of all p and less than 26% of all Λ come from the decay of doubly charged Δ and singly charged Σ* states respectively. These limits correspond to production rates of <0.10 Δ++ and <0.09 Σ*± per event (inclusive of anti-particles). Production of the decuplet states Δ++ and Σ*± is suppressed by a factor ≳9 relative to octet baryons of the same strangeness. © 1984 Springer-Verlag.
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Evidence for local compensation of baryon number in e+e- annihilation

Physics Letters B 139:1-2 (1984) 126-132

Authors:

M Althoff, W Braunschweig, FJ Kirschfink, K Lübelsmeyer, HU Martyn, J Rimkus, P Rosskamp, HG Sander, D Schmitz, H Siebke, W Wallraff, HM Fischer, H Hartmann, A Jocksch, G Knop, L Köpke, H Kolanoski, H Kück, V Mertens, R Wedemeyer, M Wollstadt, Y Eisenberg, K Gather, H Hultschig, P Joos, U Kötz, H Kowalski, A Ladage, B Löhr, D Lüke, P Mättig, KH Mess, D Notz, RJ Nowak, J Pyrlik, R Riethmüller, M Rushton, W Schütte, D Trines, G Wolf, C Xiao, R Fohrmann, E Hilger, T Kracht, HL Krasemann, P Leu, E Lohrmann, D Pandoulas, G Poelz, KU Pösnecker, P Schmüser, BH Wiik, R Beuselinck, DM Binnie, AJ Campbell, PJ Dornan, B Foster, DA Garbutt, C Jenkins, TD Jones, WG Jones, J McCardle, JK Sedgbeer, J Thomas, WAT Wan Abdullah, KW Bell, MG Bowler, P Bull, RJ Cashmore, PEL Clarke, R Devenish, P Grossmann, CM Hawkes, SL Lloyd, GL Salmon, TR Wyatt, C Youngman, GE Forden, JC Hart, J Harvey, DK Hasell, J Proudfoot, DH Saxon, PL Woodworth, F Barreiro, M Dittmar, M Holder, G Kreutz, B Neumann, E Duchovni, U Karshon, G Mikenberg, R Mir, D Revel, E Ronat, A Shapira, G Yekutieli, G Baranko, T Barklow, A Caldwell

Abstract:

We have studied at CM energies of 14, 22 and 30-36.7 GeV e+e- annihilation events in which the hadronic final state contains both a proton and an antiproton in the momentum range 1.0 < p < GeV/c. We find that such pairs are produced predominantly in the same jet and conclude that baryon-antibaryon production is dominated by a mechanism involving local compensation of baryon number. © 1984.
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