Phys. Rev. Lett.
78,
3818–3823
(1997)
Search for a Fourth Generation Charge -1/3 Quark via Flavor Changing Neutral Current Decay
S. Abachi et al. (DØ Collaboration)
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S. Abachi14, B. Abbott28, M. Abolins25, B. S. Acharya43, I. Adam12, D. L. Adams37, M. Adams17, S. Ahn14, H. Aihara22, G. A. Alves10, E. Amidi29, N. Amos24, E. W. Anderson19, R. Astur42, M. M. Baarmand42, A. Baden23, V. Balamurali32, J. Balderston16, B. Baldin14, S. Banerjee43, J. Bantly5, J. F. Bartlett14, K. Bazizi39, A. Belyaev26, S. B. Beri34, I. Bertram31, V. A. Bezzubov35, P. C. Bhat14, V. Bhatnagar34, M. Bhattacharjee13, N. Biswas32, G. Blazey30, S. Blessing15, P. Bloom7, A. Boehnlein14, N. I. Bojko35, F. Borcherding14, J. Borders39, C. Boswell9, A. Brandt14, R. Brock25, A. Bross14, D. Buchholz31, V. S. Burtovoi35, J. M. Butler3, W. Carvalho10, D. Casey39, H. Castilla-Valdez11, D. Chakraborty42, S.-M. Chang29, S. V. Chekulaev35, L.-P. Chen22, W. Chen42, S. Choi41, S. Chopra24, B. C. Choudhary9, J. H. Christenson14, M. Chung17, D. Claes27, A. R. Clark22, W. G. Cobau23, J. Cochran9, W. E. Cooper14, C. Cretsinger39, D. Cullen-Vidal5, M. A. C. Cummings16, D. Cutts5, O. I. Dahl22, K. De44, K. Del Signore24, M. Demarteau14, D. Denisov14, S. P. Denisov35, H. T. Diehl14, M. Diesburg14, G. Di Loreto25, P. Draper44, J. Drinkard8, Y. Ducros40, L. V. Dudko26, S. R. Dugad43, D. Edmunds25, J. Ellison9, V. D. Elvira42, R. Engelmann42, S. Eno23, G. Eppley37, P. Ermolov26, O. V. Eroshin35, V. N. Evdokimov35, T. Fahland8, M. Fatyga4, M. K. Fatyga39, J. Featherly4, S. Feher14, D. Fein2, T. Ferbel39, G. Finocchiaro42, H. E. Fisk14, Y. Fisyak7, E. Flattum25, G. E. Forden2, M. Fortner30, K. C. Frame25, S. Fuess14, E. Gallas44, A. N. Galyaev35, P. Gartung9, T. L. Geld25, R. J. Genik II25, K. Genser14, C. E. Gerber14, B. Gibbard4, S. Glenn7, B. Gobbi31, M. Goforth15, A. Goldschmidt22, B. Gómez1, G. Gomez23, P. I. Goncharov35, J. L. González Solís11, H. Gordon4, L. T. Goss45, A. Goussiou42, N. Graf4, P. D. Grannis42, D. R. Green14, J. Green30, H. Greenlee14, G. Grim7, N. Grossman14, P. Grudberg22, S. Grünendahl39, G. Guglielmo33, J. A. Guida2, J. M. Guida5, A. Gupta43, S. N. Gurzhiev35, P. Gutierrez33, Y. E. Gutnikov35, N. J. Hadley23, H. Haggerty14, S. Hagopian15, V. Hagopian15, K. S. Hahn39, R. E. Hall8, S. Hansen14, J. M. Hauptman19, D. Hedin30, A. P. Heinson9, U. Heintz14, R. Hernández-Montoya11, T. Heuring15, R. Hirosky15, J. D. Hobbs14, B. Hoeneisen1, J. S. Hoftun5, F. Hsieh24, Ting Hu42, Tong Hu18, T. Huehn9, A. S. Ito14, E. James2, J. Jaques32, S. A. Jerger25, R. Jesik18, J. Z.-Y. Jiang42, T. Joffe-Minor31, K. Johns2, M. Johnson14, A. Jonckheere14, M. Jones16, H. Jöstlein14, S. Y. Jun31, C. K. Jung42, S. Kahn4, G. Kalbfleisch33, J. S. Kang20, R. Kehoe32, M. L. Kelly32, C. L. Kim20, S. K. Kim41, A. Klatchko15, B. Klima14, C. Klopfenstein7, V. I. Klyukhin35, V. I. Kochetkov35, J. M. Kohli34, D. Koltick36, A. V. Kostritskiy35, J. Kotcher4, A. V. Kotwal12, J. Kourlas28, A. V. Kozelov35, E. A. Kozlovski35, J. Krane27, M. R. Krishnaswamy43, S. Krzywdzinski14, S. Kunori23, S. Lami42, H. Lan14, R. Lander7, F. Landry25, G. Landsberg14, B. Lauer19, A. Leflat26, H. Li42, J. Li44, Q. Z. Li-Demarteau14, J. G. R. Lima38, D. Lincoln24, S. L. Linn15, J. Linnemann25, R. Lipton14, Q. Liu14, Y. C. Liu31, F. Lobkowicz39, S. C. Loken22, S. Lökös42, L. Lueking14, A. L. Lyon23, A. K. A. Maciel10, R. J. Madaras22, R. Madden15, L. Magaña-Mendoza11, S. Mani7, H. S. Mao14, R. Markeloff30, L. Markosky2, T. Marshall18, M. I. Martin14, B. May31, A. A. Mayorov35, R. McCarthy42, J. McDonald15, T. McKibben17, J. McKinley25, T. McMahon33, H. L. Melanson14, M. Merkin26, K. W. Merritt14, H. Miettinen37, A. Mincer28, J. M. de Miranda10, C. S. Mishra14, N. Mokhov14, N. K. Mondal43, H. E. Montgomery14, P. Mooney1, H. da Motta10, C. Murphy17, F. Nang2, M. Narain14, V. S. Narasimham43, A. Narayanan2, H. A. Neal24, J. P. Negret1, P. Nemethy28, D. Nes̆ić5, M. Nicola10, D. Norman45, L. Oesch24, V. Oguri38, E. Oltman22, N. Oshima14, D. Owen25, P. Padley37, M. Pang19, A. Para14, Y. M. Park21, R. Partridge5, N. Parua43, M. Paterno39, J. Perkins44, M. Peters16, H. Piekarz15, Y. Pischalnikov36, V. M. Podstavkov35, B. G. Pope25, H. B. Prosper15, S. Protopopescu4, D. Pus̆eljić22, J. Qian24, P. Z. Quintas14, R. Raja14, S. Rajagopalan4, O. Ramirez17, P. A. Rapidis14, L. Rasmussen42, S. Reucroft29, M. Rijssenbeek42, T. Rockwell25, N. A. Roe22, P. Rubinov31, R. Ruchti32, J. Rutherfoord2, A. Sánchez-Hernández11, A. Santoro10, L. Sawyer44, R. D. Schamberger42, H. Schellman31, J. Sculli28, E. Shabalina26, C. Shaffer15, H. C. Shankar43, R. K. Shivpuri13, M. Shupe2, H. Singh9, J. B. Singh34, P. Singh30, V. Sirotenko30, W. Smart14, A. Smith2, R. P. Smith14, R. Snihur31, G. R. Snow27, J. Snow33, S. Snyder4, J. Solomon17, P. M. Sood34, M. Sosebee44, N. Sotnikova26, M. Souza10, A. L. Spadafora22, R. W. Stephens44, M. L. Stevenson22, D. Stewart24, D. A. Stoianova35, D. Stoker8, M. Strauss33, K. Streets28, M. Strovink22, A. Sznajder10, P. Tamburello23, J. Tarazi8, M. Tartaglia14, T. L. T. Thomas31, J. Thompson23, T. G. Trippe22, P. M. Tuts12, N. Varelas25, E. W. Varnes22, D. Vititoe2, A. A. Volkov35, A. P. Vorobiev35, H. D. Wahl15, G. Wang15, J. Warchol32, G. Watts5, M. Wayne32, H. Weerts25, A. White44, J. T. White45, J. A. Wightman19, S. Willis30, S. J. Wimpenny9, J. V. D. Wirjawan45, J. Womersley14, E. Won39, D. R. Wood29, H. Xu5, R. Yamada14, P. Yamin4, C. Yanagisawa42, J. Yang28, T. Yasuda29, P. Yepes37, C. Yoshikawa16, S. Youssef15, J. Yu14, Y. Yu41, Q. Zhu28, Z. H. Zhu39, D. Zieminska18, A. Zieminski18, E. G. Zverev26, and A. Zylberstejn40 (DØ Collaboration)
1Universidad de los Andes, Bogotá, Colombia
2University of Arizona, Tucson, Arizona 85721
3Boston University, Boston, Massachusetts 02215
4Brookhaven National Laboratory, Upton, New York 11973
5Brown University, Providence, Rhode Island 02912
6Universidad de Buenos Aires, Buenos Aires, Argentina
7University of California, Davis, California 95616
8University of California, Irvine, California 92717
9University of California, Riverside, California 92521
10LAFEX, Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro, Brazil
11CINVESTAV, Mexico City, Mexico
12Columbia University, New York, New York 10027
13Delhi University, Delhi, India 110007
14Fermi National Accelerator Laboratory, Batavia, Illinois 60510
15Florida State University, Tallahassee, Florida 32306
16University of Hawaii, Honolulu, Hawaii 96822
17University of Illinois at Chicago, Chicago, Illinois 60607
18Indiana University, Bloomington, Indiana 47405
19Iowa State University, Ames, Iowa 50011
20Korea University, Seoul, Korea
21Kyungsung University, Pusan, Korea
22Lawrence Berkeley Laboratory and University of California, Berkeley, California 94720
23University of Maryland, College Park, Maryland 20742
24University of Michigan, Ann Arbor, Michigan 48109
25Michigan State University, East Lansing, Michigan 48824
26Moscow State University, Moscow, Russia
27University of Nebraska, Lincoln, Nebraska 68588
28New York University, New York, New York 10003
29Northeastern University, Boston, Massachusetts 02115
30Northern Illinois University, DeKalb, Illinois 60115
31Northwestern University, Evanston, Illinois 60208
32University of Notre Dame, Notre Dame, Indiana 46556
33University of Oklahoma, Norman, Oklahoma 73019
34University of Panjab, Chandigarh 16-00-14, India
35Institute for High Energy Physics, 142-284 Protvino, Russia
36Purdue University, West Lafayette, Indiana 47907
37Rice University, Houston, Texas 77005
38Universidade Estadual do Rio de Janeiro, Brazil
39University of Rochester, Rochester, New York 14627
40CEA, DAPNIA/Service de Physique des Particules, CE-SACLAY, France
41Seoul National University, Seoul, Korea
42State University of New York, Stony Brook, New York 11794
43Tata Institute of Fundamental Research, Colaba, Bombay 400005, India
44University of Texas, Arlington, Texas 76019
45Texas A&M University, College Station, Texas 77843
Received 26 November 1996; published in the issue dated 19 May 1997
We report on a search for pair production of a fourth generation charge -1/3 quark ( b′) in pp̅ collisions at √s = 1.8 TeV by the DØ experiment at the Fermilab Tevatron using an integrated luminosity of 93 pb-1. Both b′ quarks are assumed to decay via flavor changing neutral currents (FCNC). The search uses the signatures γ+3 jets +μ-tag and 2γ+2 jets. We see no significant excess of events over the expected background. We place an upper limit on the production cross section times branching fraction that is well below theoretical expectations for a b′ decaying exclusively via FCNC for b′ masses up to mZ+mb.
© 1997 The American Physical Society
URL:
http://link.aps.org/doi/10.1103/PhysRevLett.78.3818
DOI:
10.1103/PhysRevLett.78.3818
PACS:
13.85.Rm, 13.40.Hq, 14.65.-q
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