Accelerator Neutrinos

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Observation of the top quark

Physical Review Letters 74:14 (1995) 2632-2637

Authors:

S Abachi, B Abbott, M Abolins, BS Acharya, I Adam, DL Adams, M Adams, S Ahn, H Aihara, J Alitti, G Alvarez, GA Alves, E Amidi, N Amos, EW Anderson, SH Aronson, R Astur, RE Avery, A Baden, V Balamurali, J Balderston, B Baldin, J Bantly, JF Bartlett, K Bazizi, J Bendich, SB Beri, I Bertram, VA Bezzubov, PC Bhat, V Bhatnagar, M Bhattacharjee, A Bischoff, N Biswas, G Blazey, S Blessing, A Boehnlein, NI Bojko, F Borcherding, J Borders, C Boswell, A Brandt, R Brock, A Bross, D Buchholz, VS Burtovoi, JM Butler, D Casey, H Castilla-Valdez, D Chakraborty, SM Chang, SV Chekulaev, LP Chen, W Chen, L Chevalier, S Chopra, BC Choudhary, JH Christenson, M Chung, D Claes, AR Clark, WG Cobau, J Cochran, WE Cooper, C Cretsinger, D Cullen-Vidal, M Cummings, D Cutts, OI Dahl, K De, M Demarteau, R Demina, K Denisenko, N Denisenko, D Denisov, SP Denisov, W Dharmaratna, HT Diehl, M Diesburg, G Di Loreto, R Dixon, P Draper, J Drinkard, Y Ducros, SR Dugad, S Durston-Johnson, D Edmunds, AO Efimov, J Ellison, VD Elvira, R Engelmann, S Eno, G Eppley, P Ermolov, OV Eroshin, VN Evdokimov, S Fahey, T Fahland, M Fatyga, MK Fatyga

Abstract:

The D0 Collaboration reports on a search for the standard model top quark in pp̄ collisions at s=1.8TeV at the Fermilab Tevatron with an integrated luminosity of approximately 50 pb-1. We have searched for tt̄ production in the dilepton and single-lepton decay channels with and without tagging of b-quark jets. We observed 17 events with an expected background of 3.8±0.6 events. The probability for an upward fluctuation of the background to produce the observed signal is 2×10-6 (equivalent to 4.6 standard deviations). The kinematic properties of the excess events are consistent with top quark decay. We conclude that we have observed the top quark and measured its mass to be 199-21+19 (stat) ±22 (syst) GeV/c2 and its production cross section to be 6.4±2.2 pb. © 1995 The American Physical Society.
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Search for W boson pair production in pp collisions at s = 1.8 TeV

Physical Review Letters 75:6 (1995) 1023-1027

Authors:

S Abachi, B Abbott, M Abolins, BS Acharya, I Adam, DL Adams, M Adams, S Ahn, H Aihara, J Alitti, G Alvarez, GA Alves, E Amidi, N Amos, EW Anderson, SH Aronson, R Astur, RE Avery, A Baden, V Balamurali, J Balderston, B Baldin, J Bantly, JF Bartlett, K Bazizi, J Bendich, SB Beri, I Bertram, VA Bezzubov, PC Bhat, V Bhatnagar, M Bhattacharjee, A Bischoff, N Biswas, G Blazey, S Blessing, A Boehnlein, NI Bojko, F Borcherding, J Borders, C Boswell, A Brandt, R Brock, A Bross, D Buchholz, VS Burtovoi, JM Butler, D Casey, H Castilla-Valdez, D Chakraborty, SM Chang, SV Chekulaev, LP Chen, W Chen, L Chevalier, S Chopra, BC Choudhary, JH Christenson, M Chung, D Claes, AR Clark, WG Cobau, J Cochran, WE Cooper, C Cretsinger, D Cullen-Vidal, M Cummings, D Cutts, OI Dahl, K De, M Demarteau, R Demina, K Denisenko, N Denisenko, D Denisov, SP Denisov, W Dharmaratna, HT Diehl, M Diesburg, G Di Loreto, R Dixon, P Draper, J Drinkard, Y Ducros, SR Dugad, S Durston-Johnson, D Edmunds, AO Efimov, J Ellison, VD Elvira, R Engelmann, S Eno, G Eppley, P Ermolov, OV Eroshin, VN Evdokimov, S Fahey, T Fahland, M Fatyga, MK Fatyga

Abstract:

The results of a search for W boson pair production in pp» collisions at s=1.8 TeV with subsequent decay to dilepton (e,ee, and) channels are presented. One event is observed with an expected background of 0.56 0.13 events with an integrated luminosity of approximately 14 pb-1. Assuming equal strengths for the WWZ and WW gauge boson coupling parameters and, limits on the CP-conserving anomalous coupling constants are -2.6< <2.8 and -2.1< <2.1 at the 95% confidence level. © 1995 The American Physical Society.
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Search for high mass top quark production in pp̄ collisions at s= 1.8 teV

Physical Review Letters 74:13 (1995) 2422-2426

Authors:

S Abachi, B Abbott, M Abolins, BS Acharya, I Adam, DL Adams, M Adams, S Ahn, H Aihara, G Alvarez, GA Alves, E Amidi, N Amos, EW Anderson, SH Aronson, R Astur, RE Avery, A Baden, V Balamurali, J Balderston, B Baldin, J Bantly, JF Bartlett, K Bazizi, T Behnke, J Bendich, SB Beri, I Bertram, VA Bezzubov, PC Bhat, V Bhatnagar, M Bhattacharjee, A Bischoff, N Biswas, G Blazey, S Blessing, A Boehnlein, NI Bojko, F Borcherding, J Borders, C Boswell, A Brandt, R Brock, A Bross, D Buchholz, VS Burtovoi, JM Butler, O Callot, D Casey, H Castilla-Valdez, D Chakraborty, SM Chang, SV Chekulaev, LP Chen, W Chen, L Chevalier, S Chopra, BC Choudhary, JH Christenson, M Chung, D Claes, AR Clark, WG Cobau, J Cochran, WE Cooper, C Cretsinger, D Cullen-Vidal, M Cummings, JP Cussonneau, D Cutts, OI Dahl, K De, M Demarteau, R Demina, K Denisenko, N Denisenko, D Denisov, SP Denisov, W Dharmaratna, HT Diehl, M Diesburg, R Dixon, P Draper, J Drinkard, Y Ducros, S Durston-Johnson, D Eartly, D Edmunds, AO Efimov, J Ellison, VD Elvira, R Engelmann, S Eno, G Eppley, P Ermolov, OV Eroshin, VN Evdokimov, S Fahey, T Fahland, M Fatyga

Abstract:

We present new results on the search for the top quark in pp̄ collisions at s=1.8 TeV with an integrated luminosity of 13.5±1.6 pb-1. We have considered tt̄ production in the standard model using electron and muon dilepton decay channels (tt̄→eμ + jets, ee + jets, and μμ + jets) and single-lepton decay channels (tt̄→e + jets and μ + jets) with and without tagging of b quark jets. From all channels we have nine events with an expected background of 3.8±0.9. If we assume that the excess is due to tt̄ production, and assume a top mass of 180 GeV/ c2, we obtain a cross section of 8.2±5.1 pb. © 1995 The American Physical Society.
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Search for squarks and gluinos in pp collisions at s=1.8 TeV

Physical Review Letters 75:4 (1995) 618-623

Authors:

S Abachi, B Abbott, M Abolins, BS Acharya, I Adam, DL Adams, M Adams, S Ahn, H Aihara, J Alitti, G Lvarez, GA Alves, E Amidi, N Amos, EW Anderson, SH Aronson, R Astur, RE Avery, A Baden, V Balamurali, J Balderston, B Baldin, J Bantly, JF Bartlett, K Bazizi, J Bendich, SB Beri, I Bertram, VA Bezzubov, PC Bhat, V Bhatnagar, M Bhattacharjee, A Bischoff, N Biswas, G Blazey, S Blessing, A Boehnlein, NI Bojko, F Borcherding, J Borders, C Boswell, A Brandt, R Brock, A Bross, D Buchholz, VS Burtovoi, JM Butler, D Casey, H Castilla-Valdez, D Chakraborty, SM Chang, SV Chekulaev, LP Chen, W Chen, L Chevalier, S Chopra, BC Choudhary, JH Christenson, M Chung, D Claes, AR Clark, WG Cobau, J Cochran, WE Cooper, C Cretsinger, D Cullen-Vidal, M Cummings, D Cutts, OI Dahl, K De, M Demarteau, R Demina, K Denisenko, N Denisenko, D Denisov, SP Denisov, W Dharmaratna, HT Diehl, M Diesburg, G Di Loreto, R Dixon, P Draper, J Drinkard, Y Ducros, SR Dugad, S Durston-Johnson, D Edmunds, AO Efimov, J Ellison, VD Elvira, R Engelmann, S Eno, G Eppley, P Ermolov, OV Eroshin, VN Evdokimov, S Fahey, T Fahland, M Fatyga, MK Fatyga

Abstract:

We present a search for events consistent with the production and decay of the squarks and gluinos of the minimal supersymmetric standard model (MSSM) in the D0 detector at the Fermilab Tevatron pp collider. We examined data for events containing large missing transverse energy and three or more jets. We observed no excess of events above the expected yield from standard model processes. For a choice of MSSM parameter values, we set a lower limit at the 95% confidence level on the mass of the gluino of 144 GeV /c2 for all squark masses and a lower limit of 212 GeV /c2 for equal squark and gluino masses. © 1995 The American Physical Society.
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Second generation leptoquark search in pp̄ collisions at s=1.8 TeV

Physical Review Letters 75:20 (1995) 3618-3623

Authors:

S Abachi, B Abbott, M Abolins, BS Acharya, I Adam, DL Adams, M Adams, S Ahn, H Aihara, J Alitti, G Alvarez, GA Alves, E Amidi, N Amos, EW Anderson, SH Aronson, R Astur, RE Avery, A Baden, V Balamurali, J Balderston, B Baldin, J Bantly, JF Bartlett, K Bazizi, J Bendich, SB Beri, I Bertram, VA Bezzubov, PC Bhat, V Bhatnagar, M Bhattacharjee, A Bischoff, N Biswas, G Blazey, S Blessing, P Bloom, A Boehnlein, NI Bojko, F Borcherding, J Borders, C Boswell, A Brandt, R Brock, A Bross, D Buchholz, VS Burtovoi, JM Butler, D Casey, H Castilla-Valdez, D Chakraborty, SM Chang, SV Chekulaev, LP Chen, W Chen, L Chevalier, S Chopra, BC Choudhary, JH Christenson, M Chung, D Claes, AR Clark, WG Cobau, J Cochran, WE Cooper, C Cretsinger, D Cullen-Vidal, MAC Cummings, D Cutts, OI Dahl, K De, M Demarteau, R Demina, K Denisenko, D Denisov, SP Denisov, W Dharmaratna, HT Diehl, M Diesburg, G Di Loreto, R Dixon, P Draper, J Drinkard, Y Ducros, SR Dugad, S Durston-Johnson, D Edmunds, J Ellison, VD Elvira, R Engelmann, S Eno, G Eppley, P Ermolov, OV Eroshin, VN Evdokimov, S Fahey, T Fahland, M Fatyga, MK Fatyga, J Featherly

Abstract:

We report on a search for second generation scalar leptoquarks with the DO detector at the Fermilab Tevatron pp̄ collider at s=1.8 TeV. This search is based on 12.7 pb-1 of data. Second generation leptoquarks are assumed to be produced in pairs and to decay into a muon and quark with branching ratio β or into a neutrino and quark with branching ratio 1-β. We obtain cross section times branching ratio limits as a function of leptoquark mass and set lower limits on the leptoquark mass at the 95% confidence level. © 1995 The American Physical Society.
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