Search for first generation scalar leptoquark pairs in pp collisions at √ s = 1.8 TeV

Physical Review Letters 80:10 (1998) 2051-2056

Authors:

B Abbott, M Abolins, BS Acharya, I Adam, DL Adams, M Adams, S Ahn, H Aihara, GA Alves, N Amos, EW Anderson, R Astur, MM Baarmand, A Baden, V Balamurali, J Balderston, B Baldin, S Banerjee, J Bantly, E Barberis, JF Bartlett, K Bazizi, A Belyaev, SB Beri, I Bertram, VA Bezzubov, PC Bhat, V Bhatnagar, M Bhattacharjee, N Biswas, G Blazey, S Blessing, P Bloom, A Boehnlein, NI Bojko, F Borcherding, C Boswell, A Brandt, R Brock, A Bross, D Buchholz, VS Burtovoi, JM Butler, W Carvalho, D Casey, Z Casilum, H Castilla-Valdez, D Chakraborty, SM Chang, SV Chekulaev, LP Chen, W Chen, S Choi, S Chopra, BC Choudhary, JH Christenson, M Chung, D Claes, AR Clark, WG Cobau, J Cochran, L Coney, WE Cooper, C Cretsinger, D Cullen-Vidal, MAC Cummings, D Cutts, OI Dahl, K Davis, K De, K Del Signore, M Demarteau, D Denisov, SP Denisov, HT Diehl, M Diesburg, G Di Loreto, P Draper, Y Ducros, LV Dudko, SR Dugad, D Edmunds, J Ellison, VD Elvira, R Engelmann, S Eno, G Eppley, P Ermolov, OV Eroshin, VN Evdokimov, T Fahland, MK Fatyga, S Feher, D Fein, T Ferbel, G Finocchiaro, HE Fisk, Y Fisyak, E Flattum, GE Forden

Abstract:

We have searched for first generation scalar leptoquark (LQ) pairs in the ev + jets channel using pp collider data (∫L dt ≈ 115pb-1) collected by the D0 experiment at the Fermilab Tevatron during 1992-1996. The analysis yields no candidate events. We combine the results with those from the ee + jets vv + jets channels to obtain 95% confidence level (C.L.) upper limits on the LQ pair production cross section as a function of mass and of β, the branching fraction to a charged lepton. Comparing with the next-to-leading order theory, we set 95% C.L. lower limits on the LQ mass of 225, 204, and 79 GeV/c2 for β = 1, 1/2, and 0, respectively. © 1998 The American Physical Society.

Search for flavor-changing neutral current decays of the top quark in pp collisions at √s = 1.8 TeV

Physical Review Letters 80:12 (1998) 2525-2530

Authors:

F Abe, H Akimoto, A Akopian, MG Albrow, SR Amendolia, D Amidei, J Antos, S Aota, G Apollinari, T Asakawa, W Ashmanskas, M Atac, F Azfar, P Azzi-Bacchetta, N Bacchetta, W Badgett, S Bagdasarov, MW Bailey, J Bao, P de Barbaro, A Barbaro-Galtieri, VE Barnes, BA Barnett, M Barone, E Barzi, G Bauer, T Baumann, F Bedeschi, S Behrends, S Belforte, G Bellettini, J Bellinger, D Benjamin, J Benlloch, J Bensinger, D Benton, A Beretvas, JP Berge, J Berryhill, S Bertolucci, S Bettelli, B Bevensee, A Bhatti, K Biery, M Binkley, D Bisello, RE Blair, C Blocker, A Bodek, W Bokhari, V Bolognesi, G Bolla, D Bortoletto, J Boudreau, L Breccia, C Bromberg, N Bruner, E Buckley-Geer, HS Budd, K Burkett, G Busetto, A Byon-Wagner, KL Byrum, J Cammerata, C Campagnari, M Campbell, A Caner, W Carithers, D Carlsmith, A Castro, D Cauz, Y Cen, F Cervelli, PS Chang, PT Chang, HY Chao, J Chapman, MT Cheng, M Chertok, G Chiarelli, T Chikamatsu, CN Chiou, L Christofek, S Cihangir, AG Clark, M Cobal, E Cocca, M Contreras, J Conway, J Cooper, M Cordelli, C Couyoumtzelis, RL Coxe, D Crane, D Cronin-Hennessy, R Culbertson, T Daniels, F De Jongh, S Delchamps, S Dell’agnello

Abstract:

We search for the flavor-changing neutral current decays of the top quark t → λ and t → qZ (here represents the c and u quarks) in pp collisions at √s = 1.8 TeV. We use a dataset (∫ L dt˜ 110pb-1) collected during the 1992-1995 run of the Collider Detector at Fermilab. We set 95% confidence level limits on the branching fractions B(t → qλ) < 3.2% and B(t → qZ) < 33%, consistent with the standard model. © 1998 The American Physical Society.

Search for heavy pointlike dirac monopoles

Physical Review Letters 81:3 (1998) 524-529

Authors:

B Abbott, M Abolins, BS Acharya, I Adam, DL Adams, M Adams, S Ahn, H Aihara, GA Alves, N Amos, EW Anderson, R Astur, MM Baarmand, L Babukhadia, A Baden, V Balamurali, J Balderston, B Baldin, S Banerjee, J Bantly, E Barberis, JF Bartlett, A Belyaev, SB Beri, I Bertram, VA Bezzubov, PC Bhat, V Bhatnagar, M Bhattacharjee, N Biswas, G Blazey, S Blessing, P Bloom, A Boehnlein, NI Bojko, F Borcherding, C Boswell, A Brandt, R Brock, A Bross, D Buchholz, VS Burtovoi, JM Butler, W Carvalho, D Casey, Z Casilum, H Castilla-Valdez, D Chakraborty, SM Chang, SV Chekulaev, LP Chen, W Chen, S Choi, S Chopra, BC Choudhary, JH Christenson, M Chung, D Claes, AR Clark, WG Cobau, J Cochran, L Coney, WE Cooper, C Cretsinger, D Cullen-Vidal, MAC Cummings, D Cutts, OI Dahl, K Davis, K De, K Del-Signore, M Demarteau, D Denisov, SP Denisov, HT Diehl, M Diesburg, G Di Loreto, P Draper, Y Ducros, LV Dudko, SR Dugad, D Edmunds, J Ellison, VD Elvira, R Engelmann, S Eno, G Eppley, P Ermolov, OV Eroshin, VN Evdokimov, T Fahland, MK Fatyga, S Feher, D Fein, T Ferbel, G Finocchiaro, HE Fisk, Y Fisyak, E Flattum, GE Forden

Abstract:

We have searched for central production of a pair of photons with high transverse energies in pp̄ collisions at √s=1.8 TeV using 70pb-1 of data collected with the D0 detector at the Fermilab Tevatron in 1994-1996. If they exist virtual heavy pointlike Dirac monopoles could rescatter pairs of nearly real photons into this final state via a box diagram. We observe no excess of events above background and set lower 95% C.L. limits of 610 870 or 1580 GeV/c2 on the mass of a spin 0 1/2 or 1 Dirac monopole. © 1998 The American Physical Society.

Search for top squark pair production in the dielectron channel

Physical Review D - Particles, Fields, Gravitation and Cosmology 57:1 (1998) 589-593

Authors:

S Abachi, B Abbott, M Abolins, BS Acharya, I Adam, DL Adams, M Adams, S Ahn, H Aihara, G Álvarez, GA Alves, E Amidi, N Amos, EW Anderson, SH Aronson, R Astur, MM Baarmand, A Baden, V Balamurali, J Balderston, B Baldin, S Banerjee, J Bantly, JF Bartlett, K Bazizi, A Belyaev, 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, W Carvalho, D Casey, H Castilla-Valdez, D Chakraborty, SM Chang, SV Chekulaev, LP Chen, W Chen, S Choi, 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, K Del Signore, M Demarteau, D Denisov, SP Denisov, HT Diehl, M Diesburg, G Di Loreto, P Draper, J Drinkard, Y Ducros, LV Dudko, SR Dugad, 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, S Feher

Abstract:

This report describes the first search for top squark pair production in the channel (Formula presented)+jets+(Formula presented) using (Formula presented) pb(Formula presented) of data collected using the DØ detector. A 95% confidence level upper limit on (Formula presented) is presented. The limit is above the theoretical expectation for (Formula presented) for this process, but does show the sensitivity of the current DØ data set to a particular topology for new physics. © 1998 The American Physical Society.

Study of semileptonic decays of [Formula presented] mesons to charmed baryons

Physical Review D Particles Fields Gravitation and Cosmology 57:11 (1998) 6604-6608

Authors:

G Bonvicini, D Cinabro, R Greene, LP Perera, GJ Zhou, M Chadha, S Chan, G Eigen, JS Miller, C O’Grady, M Schmidtler, J Urheim, AJ Weinstein, F Würthwein, DW Bliss, G Masek, HP Paar, S Prell, V Sharma, DM Asner, J Gronberg, TS Hill, DJ Lange, RJ Morrison, HN Nelson, TK Nelson, D Roberts, A Ryd, R Balest, BH Behrens, WT Ford, H Park, J Roy, JG Smith, JP Alexander, R Baker, C Bebek, BE Berger, K Berkelman, K Bloom, V Boisvert, DG Cassel, DS Crowcroft, M Dickson, S von Dombrowski, PS Drell, KM Ecklund, R Ehrlich, AD Foland, P Gaidarev, L Gibbons, B Gittelman, SW Gray, DL Hartill, BK Heltsley, PI Hopman, J Kandaswamy, PC Kim, DL Kreinick, T Lee, Y Liu, NB Mistry, CR Ng, E Nordberg, M Ogg, JR Patterson, D Peterson, D Riley, A Soffer, B Valant-Spaight, C Ward, M Athanas, P Avery, CD Jones, M Lohner, S Patton, C Prescott, J Yelton, J Zheng, G Brandenburg, RA Briere, A Ershov, YS Gao, DYJ Kim, R Wilson, H Yamamoto, TE Browder, Y Li, JL Rodriguez, T Bergfeld, BI Eisenstein, J Ernst, GE Gladding, GD Gollin, RM Hans, E Johnson, I Karliner, MA Marsh, M Palmer, M Selen

Abstract:

Using data collected by the CLEO II detector at a center-of-mass energy on or near the (Formula presented) resonance, we have determined the 90% confidence level upper limit (Formula presented) for electrons with momentum above (Formula presented) We have also obtained the limit (Formula presented) at the 90% confidence level and measured the ratio (Formula presented). © 1998 The American Physical Society.