Accelerator Neutrinos

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Search for pair production of light scalar top quarks in pp collisions at √s = 1.8 TeV

Physical Review Letters 93:1 (2004)

Authors:

VM Abazov, B Abbott, A Abdesselam, M Abolins, V Abramov, BS Acharya, DL Adams, M Adams, SN Ahmed, GD Alexeev, A Alton, GA Alves, Y Arnoud, C Avila, VV Babintsev, L Babukhadia, TC Bacon, A Baden, S Baffioni, B Baldin, PW Balm, S Banerjee, E Barberis, P Baringer, J Barreto, JF Bartlett, U Bassler, D Bauer, A Bean, F Beaudette, M Begel, A Belyaev, SB Beri, G Bernardi, I Bertram, A Besson, R Beuselinck, VA Bezzubov, PC Bhat, V Bhatnagar, M Bhattacharjee, G Blazey, F Blekman, S Blessing, A Boehnlein, NI Bojko, TA Bolton, F Borcherding, K Bos, T Bose, A Brandt, G Briskin, R Brock, G Brooijmans, A Bross, D Buchholz, M Buehler, V Buescher, VS Burtovoi, JM Butler, F Canelli, W Carvalho, D Casey, H Castilla-Valdez, D Chakraborty, KM Chan, SV Chekulaev, DK Cho, S Choi, S Chopra, D Claes, AR Clark, B Connolly, WE Cooper, D Coppage, S Crépé-Renaudin, MAC Cummings, D Cutts, H da Motta, GA Davis, K De, SJ de Jong, M Demarteau, R Demina, P Demine, D Denisov, SP Denisov, S Desai, HT Diehl, M Diesburg, S Doulas, LV Dudko, L Duflot, SR Dugad, A Duperrin, A Dyshkant, D Edmunds, J Ellison, JT Eltzroth, VD Elvira

Abstract:

The results of a search for direct pair production of scalar top quarks (t̃), the supersymmetric partners of the top quark were presented. Events containing two or more jets and missing transverse energy, the signature of light scalar top quark decays to charm quarks and neutralinos were investigated. 27 events were observed after the selection, while expecting 31.1±6.4 events from known standard model processes. The results were compared to next-to-leading-order production cross sections, and a significant region of t̃ and neutralino phase space was excluded.
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A three dimensional calculation of atmospheric neutrinos

Physical Review D 70 (2004) 023006 24pp

Authors:

GD Barr, S. A. M. Robbins, T. K. Gaisser, T. Stanev
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Focusing Solenoids for the Mice Cooling Channel

AIP Conference Proceedings AIP Publishing 710:1 (2004) 791-798

Authors:

MA Green, E Baynham, G Barr, W Lau, JH Rochford, S Yang
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A precision measurement of the mass of the top quark.

Nature 429:6992 (2004) 638-642

Authors:

VM Abazov, B Abbott, A Abdesselam, M Abolins, V Abramov, BS Acharya, DL Adams, M Adams, SN Ahmed, GD Alexeev, A Alton, GA Alves, Y Arnoud, C Avila, VV Babintsev, L Babukhadia, TC Bacon, A Baden, S Baffioni, B Baldin, PW Balm, S Banerjee, E Barberis, P Baringer, J Barreto, JF Bartlett, U Bassler, D Bauer, A Bean, F Beaudette, M Begel, A Belyaev, SB Beri, G Bernardi, I Bertram, A Besson, R Beuselinck, VA Bezzubov, PC Bhat, V Bhatnagar, M Bhattacharjee, G Blazey, F Blekman, S Blessing, A Boehnlein, NI Bojko, TA Bolton, F Borcherding, K Bos, T Bose, A Brandt, G Briskin, R Brock, G Brooijmans, A Bross, D Buchholz, M Buehler, V Buescher, VS Burtovoi, JM Butler, F Canelli, W Carvalho, D Casey, H Castilla-Valdez, D Chakraborty, KM Chan, SV Chekulaev, DK Cho, S Choi, S Chopra, D Claes, AR Clark, B Connolly, WE Cooper, D Coppage, S Crépé-Renaudin, MAC Cummings, D Cutts, H Da Motta, GA Davis, K De, SJ De Jong, M Demarteau, R Demina, P Demine, D Denisov, SP Denisov, S Desai, HT Diehl, M Diesburg, S Doulas, LV Dudko, L Duflot, SR Dugad, A Duperrin, A Dyshkant, D Edmunds, J Ellison, JT Eltzroth, VD Elvira, R Engelmann, S Eno, G Eppley, P Ermolov, OV Eroshin, J Estrada, H Evans, VN Evdokimov, T Ferbel, F Filthaut, HE Fisk, M Fortner, H Fox, S Fu, S Fuess, E Gallas, AN Galyaev, M Gao, V Gavrilov, RJ Genik, K Genser, CE Gerber, Y Gershtein, G Ginther, B Gómez, PI Goncharov, K Gounder, A Goussiou, PD Grannis, H Greenlee, ZD Greenwood, S Grinstein, L Groer, S Grünendahl, MW Grünewald, SN Gurzhiev, G Gutierrez, P Gutierrez, NJ Hadley, H Haggerty, S Hagopian, V Hagopian, RE Hall, C Han, S Hansen, JM Hauptman, C Hebert, D Hedin, JM Heinmiller, AP Heinson, U Heintz, MD Hildreth, R Hirosky, JD Hobbs, B Hoeneisen, J Huang, Y Huang, I Iashvili, R Illingworth, AS Ito, M Jaffré, S Jain, R Jesik, K Johns, M Johnson, A Jonckheere, H Jöstlein, A Juste, W Kahl, S Kahn, E Kajfasz, AM Kalinin, D Karmanov, D Karmgard, R Kehoe, S Kesisoglou, A Khanov, A Kharchilava, B Klima, JM Kohli, AV Kostritskiy, J Kotcher, B Kothari, AV Kozelov, EA Kozlovsky, J Krane, MR Krishnaswamy, P Krivkova, S Krzywdzinski, M Kubantsev, S Kuleshov, Y Kulik, S Kunori, A Kupco, VE Kuznetsov, G Landsberg, WM Lee, A Leflat, F Lehner, C Leonidopoulos, J Li, QZ Li, JGR Lima, D Lincoln, SL Linn, J Linnemann, R Lipton, A Lucotte, L Lueking, C Lundstedt, C Luo, AKA Maciel, RJ Madaras, VL Malyshev, V Manankov, HS Mao, T Marshall, MI Martin, SEK Mattingly, AA Mayorov, R McCarthy, T McMahon, HL Melanson, A Melnitchouk, A Merkin, KW Merritt, C Miao, H Miettinen, D Mihalcea, N Mokhov, NK Mondal, HE Montgomery, RW Moore, YD Mutaf, E Nagy, M Narain, VS Narasimham, NA Naumann, HA Neal, JP Negret, S Nelson, A Nomerotski, T Nunnemann, D O'Neil, V Oguri, N Oshima, P Padley, K Papageorgiou, N Parashar, R Partridge, N Parua, A Patwa, O Peters, P Pétroff, R Piegaia, BG Pope, HB Prosper, S Protopopescu, MB Przybycien, J Qian, S Rajagopalan, PA Rapidis, NW Reay, S Reucroft, M Ridel, M Rijssenbeek, F Rizatdinova, T Rockwell, C Royon, P Rubinov, R Ruchti, BM Sabirov, G Sajot, A Santoro, L Sawyer, RD Schamberger, H Schellman, A Schwartzman, E Shabalina, RK Shivpuri, D Shpakov, M Shupe, RA Sidwell, V Simak, V Sirotenko, P Slattery, RP Smith, GR Snow, J Snow, S Snyder, J Solomon, Y Song, V Sorín, M Sosebee, N Sotnikova, K Soustruznik, M Souza, NR Stanton, G Steinbrück, D Stoker, V Stolin, A Stone, DA Stoyanova, MA Strang, M Strauss, M Strovink, L Stutte, A Sznajder, M Talby, W Taylor, S Tentindo-Repond, TG Trippe, AS Turcot, PM Tuts, R Van Kooten, V Vaniev, N Varelas, F Villeneuve-Seguier, AA Volkov, AP Vorobiev, HD Wahl, Z-M Wang, J Warchol, G Watts, M Wayne, H Weerts, A White, D Whiteson, DA Wijngaarden, S Willis, SJ Wimpenny, J Womersley, DR Wood, Q Xu, R Yamada, T Yasuda, YA Yatsunenko, K Yip, J Yu, M Zanabria, X Zhang, B Zhou, Z Zhou, M Zielinski, D Zieminska, A Zieminski, V Zutshi, EG Zverev, A Zylberstejn, DØ Collaboration

Abstract:

The standard model of particle physics contains parameters--such as particle masses--whose origins are still unknown and which cannot be predicted, but whose values are constrained through their interactions. In particular, the masses of the top quark (M(t)) and W boson (M(W)) constrain the mass of the long-hypothesized, but thus far not observed, Higgs boson. A precise measurement of M(t) can therefore indicate where to look for the Higgs, and indeed whether the hypothesis of a standard model Higgs is consistent with experimental data. As top quarks are produced in pairs and decay in only about 10(-24) s into various final states, reconstructing their masses from their decay products is very challenging. Here we report a technique that extracts more information from each top-quark event and yields a greatly improved precision (of +/- 5.3 GeV/c2) when compared to previous measurements. When our new result is combined with our published measurement in a complementary decay mode and with the only other measurements available, the new world average for M(t) becomes 178.0 +/- 4.3 GeV/c2. As a result, the most likely Higgs mass increases from the experimentally excluded value of 96 to 117 GeV/c2, which is beyond current experimental sensitivity. The upper limit on the Higgs mass at the 95% confidence level is raised from 219 to 251 GeV/c2.
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Measurement of the Ξ0 → Λγ decay asymmetry and branching fraction

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 584:3-4 (2004) 251-259

Authors:

A Lai, D Marras, A Bevan, RS Dosanjh, TJ Gershon, B Hay, GE Kalmus, C Lazzeroni, DJ Munday, E Olaiya, MA Parker, TO White, SA Wotton, G Barr, G Bocquet, A Ceccucci, T Cuhadar-Dönszelmann, D Cundy, G D'Agostini, N Doble, V Falaleev, L Gatignon, A Gonidec, B Gorini, G Govi, P Grafström, W Kubischta, A Lacourt, A Norton, S Palestini, B Panzer-Steindel, H Taureg, M Velasco, H Wahl, C Cheshkov, A Gaponenko, P Hristov, V Kekelidze, D Madigojine, N Molokanova, Y Potrebenikov, G Tatishvili, A Tkatchev, A Zinchenko, I Knowles, V Martin, R Sacco, A Walker, M Contalbrigo, P Dalpiaz, J Duclos, PL Frabetti, A Gianoli, M Martini, F Petrucci, M Savrié, A Bizzeti, M Calvetti, G Collazuol, G Graziani, E Iacopini, M Lenti, F Martelli, M Veltri, HG Becker, K Eppard, M Eppard, H Fox, A Kalter, K Kleinknecht, U Koch, L Köpke, P Lopes da Silva, P Marouelli, I Pellmann, A Peters, B Renk, SA Schmidt, V Schönharting, Y Schué, R Wanke, A Winhart, M Wittgen, JC Chollet, L Fayard, L Iconomidou-Fayard, J Ocariz, G Unal, I Wingerter-Seez, G Anzivino, P Cenci, E Imbergamo, P Lubrano, A Mestvirishvili, A Nappi, M Pepe, M Piccini, L Bertanza, R Carosi, R Casali

Abstract:

In data taken with the NA48 experiment at the CERN SPS in 1999, 730 candidates of the weak radiative hyperon decay Ξ0→Λγ have been found with an estimated background of 58±8 events. From these events the Ξ0→Λγ decay asymmetry has been determined to α(Ξ0→Λγ)=-0.78±0.18stat±0.06 syst, which is the first evidence of a decay asymmetry in Ξ 0→Λγ. The branching fraction of the decay has been measured to be Br(Ξ0→Λγ)=(1.16±0.05 stat±0.06syst)×10-3. © 2004 Elsevier B.V. All rights reserved.
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