CDF Collaboration222With visitors from aUniversity of Massachusetts Amherst,
Amherst, Massachusetts 01003, bIstituto Nazionale di Fisica Nucleare, Sezione
di Cagliari, 09042 Monserrato (Cagliari), Italy, cUniversity of California
Irvine, Irvine, CA 92697, dUniversity of California Santa Barbara, Santa
Barbara, CA 93106 eUniversity of California Santa Cruz, Santa Cruz, CA 95064,
fCERN,CH-1211 Geneva, Switzerland, gCornell University, Ithaca, NY 14853,
hUniversity of Cyprus, Nicosia CY-1678, Cyprus, iUniversity College Dublin,
Dublin 4, Ireland, jUniversity of Fukui, Fukui City, Fukui Prefecture, Japan
910-0017, kUniversidad Iberoamericana, Mexico D.F., Mexico, lIowa State
University, Ames, IA 50011, mUniversity of Iowa, Iowa City, IA 52242, nKinki
University, Higashi-Osaka City, Japan 577-8502, oKansas State University,
Manhattan, KS 66506, pUniversity of Manchester, Manchester M13 9PL, England,
qQueen Mary, University of London, London, E1 4NS, England, rMuons, Inc.,
Batavia, IL 60510, sNagasaki Institute of Applied Science, Nagasaki, Japan,
tNational Research Nuclear University, Moscow, Russia, uUniversity of Notre
Dame, Notre Dame, IN 46556, vUniversidad de Oviedo, E-33007 Oviedo, Spain,
wTexas Tech University, Lubbock, TX 79609, xUniversidad Tecnica Federico Santa
Maria, 110v Valparaiso, Chile, yYarmouk University, Irbid 211-63, Jordan, ggOn
leave from J. Stefan Institute, Ljubljana, Slovenia,

# First Search for Multijet Resonances in $\sqrt{s}=1.96$ TeV $p\bar{p}$
Collisions

T. Aaltonen  Division of High Energy Physics, Department of Physics,
University of Helsinki and Helsinki Institute of Physics, FIN-00014, Helsinki,
Finland  B. Álvarez Gonzálezv Instituto de Fisica de Cantabria, CSIC-
University of Cantabria, 39005 Santander, Spain  S. Amerio  Istituto Nazionale
di Fisica Nucleare, Sezione di Padova-Trento, aaUniversity of Padova, I-35131
Padova, Italy  D. Amidei  University of Michigan, Ann Arbor, Michigan 48109,
USA  A. Anastassov  Northwestern University, Evanston, Illinois 60208, USA  A.
Annovi  Laboratori Nazionali di Frascati, Istituto Nazionale di Fisica
Nucleare, I-00044 Frascati, Italy  J. Antos  Comenius University, 842 48
Bratislava, Slovakia; Institute of Experimental Physics, 040 01 Kosice,
Slovakia  G. Apollinari  Fermi National Accelerator Laboratory, Batavia,
Illinois 60510, USA  J.A. Appel  Fermi National Accelerator Laboratory,
Batavia, Illinois 60510, USA  A. Apresyan  Purdue University, West Lafayette,
Indiana 47907, USA  T. Arisawa  Waseda University, Tokyo 169, Japan  A.
Artikov  Joint Institute for Nuclear Research, RU-141980 Dubna, Russia  J.
Asaadi  Texas A&M University, College Station, Texas 77843, USA  W. Ashmanskas
Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA  B.
Auerbach  Yale University, New Haven, Connecticut 06520, USA  A. Aurisano
Texas A&M University, College Station, Texas 77843, USA  F. Azfar  University
of Oxford, Oxford OX1 3RH, United Kingdom  W. Badgett  Fermi National
Accelerator Laboratory, Batavia, Illinois 60510, USA  A. Barbaro-Galtieri
Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, California
94720, USA  V.E. Barnes  Purdue University, West Lafayette, Indiana 47907, USA
B.A. Barnett  The Johns Hopkins University, Baltimore, Maryland 21218, USA  P.
Barriacc Istituto Nazionale di Fisica Nucleare Pisa, bbUniversity of Pisa,
ccUniversity of Siena and ddScuola Normale Superiore, I-56127 Pisa, Italy  P.
Bartos  Comenius University, 842 48 Bratislava, Slovakia; Institute of
Experimental Physics, 040 01 Kosice, Slovakia  M. Bauceaa Istituto Nazionale
di Fisica Nucleare, Sezione di Padova-Trento, aaUniversity of Padova, I-35131
Padova, Italy  G. Bauer  Massachusetts Institute of Technology, Cambridge,
Massachusetts 02139, USA  F. Bedeschi  Istituto Nazionale di Fisica Nucleare
Pisa, bbUniversity of Pisa, ccUniversity of Siena and ddScuola Normale
Superiore, I-56127 Pisa, Italy  D. Beecher  University College London, London
WC1E 6BT, United Kingdom  S. Behari  The Johns Hopkins University, Baltimore,
Maryland 21218, USA  G. Bellettinibb Istituto Nazionale di Fisica Nucleare
Pisa, bbUniversity of Pisa, ccUniversity of Siena and ddScuola Normale
Superiore, I-56127 Pisa, Italy  J. Bellinger  University of Wisconsin,
Madison, Wisconsin 53706, USA  D. Benjamin  Duke University, Durham, North
Carolina 27708, USA  A. Beretvas  Fermi National Accelerator Laboratory,
Batavia, Illinois 60510, USA  A. Bhatti  The Rockefeller University, New York,
New York 10065, USA  M. Binkley111Deceased Fermi National Accelerator
Laboratory, Batavia, Illinois 60510, USA  D. Biselloaa Istituto Nazionale di
Fisica Nucleare, Sezione di Padova-Trento, aaUniversity of Padova, I-35131
Padova, Italy  I. Bizjakgg University College London, London WC1E 6BT, United
Kingdom  K.R. Bland  Baylor University, Waco, Texas 76798, USA  B. Blumenfeld
The Johns Hopkins University, Baltimore, Maryland 21218, USA  A. Bocci  Duke
University, Durham, North Carolina 27708, USA  A. Bodek  University of
Rochester, Rochester, New York 14627, USA  D. Bortoletto  Purdue University,
West Lafayette, Indiana 47907, USA  J. Boudreau  University of Pittsburgh,
Pittsburgh, Pennsylvania 15260, USA  A. Boveia  Enrico Fermi Institute,
University of Chicago, Chicago, Illinois 60637, USA  B. Braua Fermi National
Accelerator Laboratory, Batavia, Illinois 60510, USA  L. Brigliadoriz Istituto
Nazionale di Fisica Nucleare Bologna, zUniversity of Bologna, I-40127 Bologna,
Italy  A. Brisuda  Comenius University, 842 48 Bratislava, Slovakia; Institute
of Experimental Physics, 040 01 Kosice, Slovakia  C. Bromberg  Michigan State
University, East Lansing, Michigan 48824, USA  E. Brucken  Division of High
Energy Physics, Department of Physics, University of Helsinki and Helsinki
Institute of Physics, FIN-00014, Helsinki, Finland  M. Bucciantoniobb Istituto
Nazionale di Fisica Nucleare Pisa, bbUniversity of Pisa, ccUniversity of Siena
and ddScuola Normale Superiore, I-56127 Pisa, Italy  J. Budagov  Joint
Institute for Nuclear Research, RU-141980 Dubna, Russia  H.S. Budd  University
of Rochester, Rochester, New York 14627, USA  S. Budd  University of Illinois,
Urbana, Illinois 61801, USA  K. Burkett  Fermi National Accelerator
Laboratory, Batavia, Illinois 60510, USA  G. Busettoaa Istituto Nazionale di
Fisica Nucleare, Sezione di Padova-Trento, aaUniversity of Padova, I-35131
Padova, Italy  P. Bussey  Glasgow University, Glasgow G12 8QQ, United Kingdom
A. Buzatu  Institute of Particle Physics: McGill University, Montréal, Québec,
Canada H3A 2T8; Simon Fraser University, Burnaby, British Columbia, Canada V5A
1S6; University of Toronto, Toronto, Ontario, Canada M5S 1A7; and TRIUMF,
Vancouver, British Columbia, Canada V6T 2A3  C. Calancha  Centro de
Investigaciones Energeticas Medioambientales y Tecnologicas, E-28040 Madrid,
Spain  S. Camarda  Institut de Fisica d’Altes Energies, ICREA, Universitat
Autonoma de Barcelona, E-08193, Bellaterra (Barcelona), Spain  M. Campanelli
Michigan State University, East Lansing, Michigan 48824, USA  M. Campbell
University of Michigan, Ann Arbor, Michigan 48109, USA  F. Canelli12 Fermi
National Accelerator Laboratory, Batavia, Illinois 60510, USA  A. Canepa
University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA  B. Carls
University of Illinois, Urbana, Illinois 61801, USA  D. Carlsmith  University
of Wisconsin, Madison, Wisconsin 53706, USA  R. Carosi  Istituto Nazionale di
Fisica Nucleare Pisa, bbUniversity of Pisa, ccUniversity of Siena and ddScuola
Normale Superiore, I-56127 Pisa, Italy  S. Carrillok University of Florida,
Gainesville, Florida 32611, USA  S. Carron  Fermi National Accelerator
Laboratory, Batavia, Illinois 60510, USA  B. Casal  Instituto de Fisica de
Cantabria, CSIC-University of Cantabria, 39005 Santander, Spain  M. Casarsa
Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA  A.
Castroz Istituto Nazionale di Fisica Nucleare Bologna, zUniversity of Bologna,
I-40127 Bologna, Italy  P. Catastini  Fermi National Accelerator Laboratory,
Batavia, Illinois 60510, USA  D. Cauz  Istituto Nazionale di Fisica Nucleare
Trieste/Udine, I-34100 Trieste, ffUniversity of Trieste/Udine, I-33100 Udine,
Italy  V. Cavalierecc Istituto Nazionale di Fisica Nucleare Pisa, bbUniversity
of Pisa, ccUniversity of Siena and ddScuola Normale Superiore, I-56127 Pisa,
Italy  M. Cavalli-Sforza  Institut de Fisica d’Altes Energies, ICREA,
Universitat Autonoma de Barcelona, E-08193, Bellaterra (Barcelona), Spain  A.
Cerrif Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley,
California 94720, USA  L. Cerritoq University College London, London WC1E 6BT,
United Kingdom  Y.C. Chen  Institute of Physics, Academia Sinica, Taipei,
Taiwan 11529, Republic of China  M. Chertok  University of California, Davis,
Davis, California 95616, USA  G. Chiarelli  Istituto Nazionale di Fisica
Nucleare Pisa, bbUniversity of Pisa, ccUniversity of Siena and ddScuola
Normale Superiore, I-56127 Pisa, Italy  G. Chlachidze  Fermi National
Accelerator Laboratory, Batavia, Illinois 60510, USA  F. Chlebana  Fermi
National Accelerator Laboratory, Batavia, Illinois 60510, USA  K. Cho  Center
for High Energy Physics: Kyungpook National University, Daegu 702-701, Korea;
Seoul National University, Seoul 151-742, Korea; Sungkyunkwan University,
Suwon 440-746, Korea; Korea Institute of Science and Technology Information,
Daejeon 305-806, Korea; Chonnam National University, Gwangju 500-757, Korea;
Chonbuk National University, Jeonju 561-756, Korea  D. Chokheli  Joint
Institute for Nuclear Research, RU-141980 Dubna, Russia  J.P. Chou  Harvard
University, Cambridge, Massachusetts 02138, USA  W.H. Chung  University of
Wisconsin, Madison, Wisconsin 53706, USA  Y.S. Chung  University of Rochester,
Rochester, New York 14627, USA  C.I. Ciobanu  LPNHE, Universite Pierre et
Marie Curie/IN2P3-CNRS, UMR7585, Paris, F-75252 France  M.A. Cioccicc Istituto
Nazionale di Fisica Nucleare Pisa, bbUniversity of Pisa, ccUniversity of Siena
and ddScuola Normale Superiore, I-56127 Pisa, Italy  A. Clark  University of
Geneva, CH-1211 Geneva 4, Switzerland  G. Compostellaaa Istituto Nazionale di
Fisica Nucleare, Sezione di Padova-Trento, aaUniversity of Padova, I-35131
Padova, Italy  M.E. Convery  Fermi National Accelerator Laboratory, Batavia,
Illinois 60510, USA  J. Conway  University of California, Davis, Davis,
California 95616, USA  M.Corbo  LPNHE, Universite Pierre et Marie
Curie/IN2P3-CNRS, UMR7585, Paris, F-75252 France  M. Cordelli  Laboratori
Nazionali di Frascati, Istituto Nazionale di Fisica Nucleare, I-00044
Frascati, Italy  C.A. Cox  University of California, Davis, Davis, California
95616, USA  D.J. Cox  University of California, Davis, Davis, California
95616, USA  F. Cresciolibb Istituto Nazionale di Fisica Nucleare Pisa,
bbUniversity of Pisa, ccUniversity of Siena and ddScuola Normale Superiore,
I-56127 Pisa, Italy  C. Cuenca Almenar  Yale University, New Haven,
Connecticut 06520, USA  J. Cuevasv Instituto de Fisica de Cantabria, CSIC-
University of Cantabria, 39005 Santander, Spain  R. Culbertson  Fermi National
Accelerator Laboratory, Batavia, Illinois 60510, USA  D. Dagenhart  Fermi
National Accelerator Laboratory, Batavia, Illinois 60510, USA  N. d’Ascenzot
LPNHE, Universite Pierre et Marie Curie/IN2P3-CNRS, UMR7585, Paris, F-75252
France  M. Datta  Fermi National Accelerator Laboratory, Batavia, Illinois
60510, USA  P. de Barbaro  University of Rochester, Rochester, New York 14627,
USA  S. De Cecco  Istituto Nazionale di Fisica Nucleare, Sezione di Roma 1,
eeSapienza Università di Roma, I-00185 Roma, Italy  G. De Lorenzo  Institut de
Fisica d’Altes Energies, ICREA, Universitat Autonoma de Barcelona, E-08193,
Bellaterra (Barcelona), Spain  M. Dell’Orsobb Istituto Nazionale di Fisica
Nucleare Pisa, bbUniversity of Pisa, ccUniversity of Siena and ddScuola
Normale Superiore, I-56127 Pisa, Italy  C. Deluca  Institut de Fisica d’Altes
Energies, ICREA, Universitat Autonoma de Barcelona, E-08193, Bellaterra
(Barcelona), Spain  L. Demortier  The Rockefeller University, New York, New
York 10065, USA  J. Dengc Duke University, Durham, North Carolina 27708, USA
M. Deninno  Istituto Nazionale di Fisica Nucleare Bologna, zUniversity of
Bologna, I-40127 Bologna, Italy  F. Devoto  Division of High Energy Physics,
Department of Physics, University of Helsinki and Helsinki Institute of
Physics, FIN-00014, Helsinki, Finland  M. d’Erricoaa Istituto Nazionale di
Fisica Nucleare, Sezione di Padova-Trento, aaUniversity of Padova, I-35131
Padova, Italy  A. Di Cantobb Istituto Nazionale di Fisica Nucleare Pisa,
bbUniversity of Pisa, ccUniversity of Siena and ddScuola Normale Superiore,
I-56127 Pisa, Italy  B. Di Ruzza  Istituto Nazionale di Fisica Nucleare Pisa,
bbUniversity of Pisa, ccUniversity of Siena and ddScuola Normale Superiore,
I-56127 Pisa, Italy  J.R. Dittmann  Baylor University, Waco, Texas 76798, USA
M. D’Onofrio  University of Liverpool, Liverpool L69 7ZE, United Kingdom  S.
Donatibb Istituto Nazionale di Fisica Nucleare Pisa, bbUniversity of Pisa,
ccUniversity of Siena and ddScuola Normale Superiore, I-56127 Pisa, Italy  P.
Dong  Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA  M.
Dorigo  Istituto Nazionale di Fisica Nucleare Trieste/Udine, I-34100 Trieste,
ffUniversity of Trieste/Udine, I-33100 Udine, Italy  T. Dorigo  Istituto
Nazionale di Fisica Nucleare, Sezione di Padova-Trento, aaUniversity of
Padova, I-35131 Padova, Italy  K. Ebina  Waseda University, Tokyo 169, Japan
A. Elagin  Texas A&M University, College Station, Texas 77843, USA  A. Eppig
University of Michigan, Ann Arbor, Michigan 48109, USA  R. Erbacher
University of California, Davis, Davis, California 95616, USA  D. Errede
University of Illinois, Urbana, Illinois 61801, USA  S. Errede  University of
Illinois, Urbana, Illinois 61801, USA  N. Ershaidaty LPNHE, Universite Pierre
et Marie Curie/IN2P3-CNRS, UMR7585, Paris, F-75252 France  R. Eusebi  Texas
A&M University, College Station, Texas 77843, USA  H.C. Fang  Ernest Orlando
Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA  S.
Farrington  University of Oxford, Oxford OX1 3RH, United Kingdom  M. Feindt
Institut für Experimentelle Kernphysik, Karlsruhe Institute of Technology,
D-76131 Karlsruhe, Germany  J.P. Fernandez  Centro de Investigaciones
Energeticas Medioambientales y Tecnologicas, E-28040 Madrid, Spain  C.
Ferrazzadd Istituto Nazionale di Fisica Nucleare Pisa, bbUniversity of Pisa,
ccUniversity of Siena and ddScuola Normale Superiore, I-56127 Pisa, Italy  R.
Field  University of Florida, Gainesville, Florida 32611, USA  G. Flanaganr
Purdue University, West Lafayette, Indiana 47907, USA  R. Forrest  University
of California, Davis, Davis, California 95616, USA  M.J. Frank  Baylor
University, Waco, Texas 76798, USA  M. Franklin  Harvard University,
Cambridge, Massachusetts 02138, USA  J.C. Freeman  Fermi National Accelerator
Laboratory, Batavia, Illinois 60510, USA  Y. Funakoshi  Waseda University,
Tokyo 169, Japan  I. Furic  University of Florida, Gainesville, Florida 32611,
USA  M. Gallinaro  The Rockefeller University, New York, New York 10065, USA
J. Galyardt  Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
J.E. Garcia  University of Geneva, CH-1211 Geneva 4, Switzerland  A.F.
Garfinkel  Purdue University, West Lafayette, Indiana 47907, USA  P. Garosicc
Istituto Nazionale di Fisica Nucleare Pisa, bbUniversity of Pisa, ccUniversity
of Siena and ddScuola Normale Superiore, I-56127 Pisa, Italy  H. Gerberich
University of Illinois, Urbana, Illinois 61801, USA  E. Gerchtein  Fermi
National Accelerator Laboratory, Batavia, Illinois 60510, USA  S. Giaguee
Istituto Nazionale di Fisica Nucleare, Sezione di Roma 1, eeSapienza
Università di Roma, I-00185 Roma, Italy  V. Giakoumopoulou  University of
Athens, 157 71 Athens, Greece  P. Giannetti  Istituto Nazionale di Fisica
Nucleare Pisa, bbUniversity of Pisa, ccUniversity of Siena and ddScuola
Normale Superiore, I-56127 Pisa, Italy  K. Gibson  University of Pittsburgh,
Pittsburgh, Pennsylvania 15260, USA  C.M. Ginsburg  Fermi National Accelerator
Laboratory, Batavia, Illinois 60510, USA  N. Giokaris  University of Athens,
157 71 Athens, Greece  P. Giromini  Laboratori Nazionali di Frascati, Istituto
Nazionale di Fisica Nucleare, I-00044 Frascati, Italy  M. Giunta  Istituto
Nazionale di Fisica Nucleare Pisa, bbUniversity of Pisa, ccUniversity of Siena
and ddScuola Normale Superiore, I-56127 Pisa, Italy  G. Giurgiu  The Johns
Hopkins University, Baltimore, Maryland 21218, USA  V. Glagolev  Joint
Institute for Nuclear Research, RU-141980 Dubna, Russia  D. Glenzinski  Fermi
National Accelerator Laboratory, Batavia, Illinois 60510, USA  M. Gold
University of New Mexico, Albuquerque, New Mexico 87131, USA  D. Goldin  Texas
A&M University, College Station, Texas 77843, USA  N. Goldschmidt  University
of Florida, Gainesville, Florida 32611, USA  A. Golossanov  Fermi National
Accelerator Laboratory, Batavia, Illinois 60510, USA  G. Gomez  Instituto de
Fisica de Cantabria, CSIC-University of Cantabria, 39005 Santander, Spain  G.
Gomez-Ceballos  Massachusetts Institute of Technology, Cambridge,
Massachusetts 02139, USA  M. Goncharov  Massachusetts Institute of Technology,
Cambridge, Massachusetts 02139, USA  O. González  Centro de Investigaciones
Energeticas Medioambientales y Tecnologicas, E-28040 Madrid, Spain  I. Gorelov
University of New Mexico, Albuquerque, New Mexico 87131, USA  A.T. Goshaw
Duke University, Durham, North Carolina 27708, USA  K. Goulianos  The
Rockefeller University, New York, New York 10065, USA  A. Gresele  Istituto
Nazionale di Fisica Nucleare, Sezione di Padova-Trento, aaUniversity of
Padova, I-35131 Padova, Italy  S. Grinstein  Institut de Fisica d’Altes
Energies, ICREA, Universitat Autonoma de Barcelona, E-08193, Bellaterra
(Barcelona), Spain  C. Grosso-Pilcher  Enrico Fermi Institute, University of
Chicago, Chicago, Illinois 60637, USA  R.C. Group  University of Virginia,
Charlottesville, VA 22906, USA  J. Guimaraes da Costa  Harvard University,
Cambridge, Massachusetts 02138, USA  Z. Gunay-Unalan  Michigan State
University, East Lansing, Michigan 48824, USA  C. Haber  Ernest Orlando
Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA  S.R.
Hahn  Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA  E.
Halkiadakis  Rutgers University, Piscataway, New Jersey 08855, USA  A.
Hamaguchi  Osaka City University, Osaka 588, Japan  J.Y. Han  University of
Rochester, Rochester, New York 14627, USA  F. Happacher  Laboratori Nazionali
di Frascati, Istituto Nazionale di Fisica Nucleare, I-00044 Frascati, Italy
K. Hara  University of Tsukuba, Tsukuba, Ibaraki 305, Japan  D. Hare  Rutgers
University, Piscataway, New Jersey 08855, USA  M. Hare  Tufts University,
Medford, Massachusetts 02155, USA  R.F. Harr  Wayne State University, Detroit,
Michigan 48201, USA  K. Hatakeyama  Baylor University, Waco, Texas 76798, USA
C. Hays  University of Oxford, Oxford OX1 3RH, United Kingdom  M. Heck
Institut für Experimentelle Kernphysik, Karlsruhe Institute of Technology,
D-76131 Karlsruhe, Germany  J. Heinrich  University of Pennsylvania,
Philadelphia, Pennsylvania 19104, USA  M. Herndon  University of Wisconsin,
Madison, Wisconsin 53706, USA  S. Hewamanage  Baylor University, Waco, Texas
76798, USA  D. Hidas  Rutgers University, Piscataway, New Jersey 08855, USA
A. Hocker  Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA
W. Hopkinsg Fermi National Accelerator Laboratory, Batavia, Illinois 60510,
USA  D. Horn  Institut für Experimentelle Kernphysik, Karlsruhe Institute of
Technology, D-76131 Karlsruhe, Germany  S. Hou  Institute of Physics, Academia
Sinica, Taipei, Taiwan 11529, Republic of China  R.E. Hughes  The Ohio State
University, Columbus, Ohio 43210, USA  M. Hurwitz  Enrico Fermi Institute,
University of Chicago, Chicago, Illinois 60637, USA  U. Husemann  Yale
University, New Haven, Connecticut 06520, USA  N. Hussain  Institute of
Particle Physics: McGill University, Montréal, Québec, Canada H3A 2T8; Simon
Fraser University, Burnaby, British Columbia, Canada V5A 1S6; University of
Toronto, Toronto, Ontario, Canada M5S 1A7; and TRIUMF, Vancouver, British
Columbia, Canada V6T 2A3  M. Hussein  Michigan State University, East Lansing,
Michigan 48824, USA  J. Huston  Michigan State University, East Lansing,
Michigan 48824, USA  G. Introzzi  Istituto Nazionale di Fisica Nucleare Pisa,
bbUniversity of Pisa, ccUniversity of Siena and ddScuola Normale Superiore,
I-56127 Pisa, Italy  M. Ioriee Istituto Nazionale di Fisica Nucleare, Sezione
di Roma 1, eeSapienza Università di Roma, I-00185 Roma, Italy  A. Ivanovo
University of California, Davis, Davis, California 95616, USA  G. Jain
Rutgers University, Piscataway, New Jersey 08855, USA  E. James  Fermi
National Accelerator Laboratory, Batavia, Illinois 60510, USA  D. Jang
Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA  B. Jayatilaka
Duke University, Durham, North Carolina 27708, USA  E.J. Jeon  Center for High
Energy Physics: Kyungpook National University, Daegu 702-701, Korea; Seoul
National University, Seoul 151-742, Korea; Sungkyunkwan University, Suwon
440-746, Korea; Korea Institute of Science and Technology Information, Daejeon
305-806, Korea; Chonnam National University, Gwangju 500-757, Korea; Chonbuk
National University, Jeonju 561-756, Korea  M.K. Jha  Istituto Nazionale di
Fisica Nucleare Bologna, zUniversity of Bologna, I-40127 Bologna, Italy  S.
Jindariani  Fermi National Accelerator Laboratory, Batavia, Illinois 60510,
USA  W. Johnson  University of California, Davis, Davis, California 95616, USA
M. Jones  Purdue University, West Lafayette, Indiana 47907, USA  K.K. Joo
Center for High Energy Physics: Kyungpook National University, Daegu 702-701,
Korea; Seoul National University, Seoul 151-742, Korea; Sungkyunkwan
University, Suwon 440-746, Korea; Korea Institute of Science and Technology
Information, Daejeon 305-806, Korea; Chonnam National University, Gwangju
500-757, Korea; Chonbuk National University, Jeonju 561-756, Korea  S.Y. Jun
Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA  T.R. Junk
Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA  T. Kamon
Texas A&M University, College Station, Texas 77843, USA  P.E. Karchin  Wayne
State University, Detroit, Michigan 48201, USA  Y. Katon Osaka City
University, Osaka 588, Japan  W. Ketchum  Enrico Fermi Institute, University
of Chicago, Chicago, Illinois 60637, USA  J. Keung  University of
Pennsylvania, Philadelphia, Pennsylvania 19104, USA  V. Khotilovich  Texas A&M
University, College Station, Texas 77843, USA  B. Kilminster  Fermi National
Accelerator Laboratory, Batavia, Illinois 60510, USA  D.H. Kim  Center for
High Energy Physics: Kyungpook National University, Daegu 702-701, Korea;
Seoul National University, Seoul 151-742, Korea; Sungkyunkwan University,
Suwon 440-746, Korea; Korea Institute of Science and Technology Information,
Daejeon 305-806, Korea; Chonnam National University, Gwangju 500-757, Korea;
Chonbuk National University, Jeonju 561-756, Korea  H.S. Kim  Center for High
Energy Physics: Kyungpook National University, Daegu 702-701, Korea; Seoul
National University, Seoul 151-742, Korea; Sungkyunkwan University, Suwon
440-746, Korea; Korea Institute of Science and Technology Information, Daejeon
305-806, Korea; Chonnam National University, Gwangju 500-757, Korea; Chonbuk
National University, Jeonju 561-756, Korea  H.W. Kim  Center for High Energy
Physics: Kyungpook National University, Daegu 702-701, Korea; Seoul National
University, Seoul 151-742, Korea; Sungkyunkwan University, Suwon 440-746,
Korea; Korea Institute of Science and Technology Information, Daejeon 305-806,
Korea; Chonnam National University, Gwangju 500-757, Korea; Chonbuk National
University, Jeonju 561-756, Korea  J.E. Kim  Center for High Energy Physics:
Kyungpook National University, Daegu 702-701, Korea; Seoul National
University, Seoul 151-742, Korea; Sungkyunkwan University, Suwon 440-746,
Korea; Korea Institute of Science and Technology Information, Daejeon 305-806,
Korea; Chonnam National University, Gwangju 500-757, Korea; Chonbuk National
University, Jeonju 561-756, Korea  M.J. Kim  Laboratori Nazionali di Frascati,
Istituto Nazionale di Fisica Nucleare, I-00044 Frascati, Italy  S.B. Kim
Center for High Energy Physics: Kyungpook National University, Daegu 702-701,
Korea; Seoul National University, Seoul 151-742, Korea; Sungkyunkwan
University, Suwon 440-746, Korea; Korea Institute of Science and Technology
Information, Daejeon 305-806, Korea; Chonnam National University, Gwangju
500-757, Korea; Chonbuk National University, Jeonju 561-756, Korea  S.H. Kim
University of Tsukuba, Tsukuba, Ibaraki 305, Japan  Y.K. Kim  Enrico Fermi
Institute, University of Chicago, Chicago, Illinois 60637, USA  N. Kimura
Waseda University, Tokyo 169, Japan  M. Kirby  Fermi National Accelerator
Laboratory, Batavia, Illinois 60510, USA  S. Klimenko  University of Florida,
Gainesville, Florida 32611, USA  K. Kondo  Waseda University, Tokyo 169, Japan
D.J. Kong  Center for High Energy Physics: Kyungpook National University,
Daegu 702-701, Korea; Seoul National University, Seoul 151-742, Korea;
Sungkyunkwan University, Suwon 440-746, Korea; Korea Institute of Science and
Technology Information, Daejeon 305-806, Korea; Chonnam National University,
Gwangju 500-757, Korea; Chonbuk National University, Jeonju 561-756, Korea  J.
Konigsberg  University of Florida, Gainesville, Florida 32611, USA  A.V.
Kotwal  Duke University, Durham, North Carolina 27708, USA  M. Kreps  Institut
für Experimentelle Kernphysik, Karlsruhe Institute of Technology, D-76131
Karlsruhe, Germany  J. Kroll  University of Pennsylvania, Philadelphia,
Pennsylvania 19104, USA  D. Krop  Enrico Fermi Institute, University of
Chicago, Chicago, Illinois 60637, USA  N. Krumnackl Baylor University, Waco,
Texas 76798, USA  M. Kruse  Duke University, Durham, North Carolina 27708, USA
V. Krutelyovd Texas A&M University, College Station, Texas 77843, USA  T. Kuhr
Institut für Experimentelle Kernphysik, Karlsruhe Institute of Technology,
D-76131 Karlsruhe, Germany  M. Kurata  University of Tsukuba, Tsukuba, Ibaraki
305, Japan  S. Kwang  Enrico Fermi Institute, University of Chicago, Chicago,
Illinois 60637, USA  A.T. Laasanen  Purdue University, West Lafayette, Indiana
47907, USA  S. Lami  Istituto Nazionale di Fisica Nucleare Pisa, bbUniversity
of Pisa, ccUniversity of Siena and ddScuola Normale Superiore, I-56127 Pisa,
Italy  S. Lammel  Fermi National Accelerator Laboratory, Batavia, Illinois
60510, USA  M. Lancaster  University College London, London WC1E 6BT, United
Kingdom  R.L. Lander  University of California, Davis, Davis, California
95616, USA  K. Lannonu The Ohio State University, Columbus, Ohio 43210, USA
A. Lath  Rutgers University, Piscataway, New Jersey 08855, USA  G. Latinocc
Istituto Nazionale di Fisica Nucleare Pisa, bbUniversity of Pisa, ccUniversity
of Siena and ddScuola Normale Superiore, I-56127 Pisa, Italy  I. Lazzizzera
Istituto Nazionale di Fisica Nucleare, Sezione di Padova-Trento, aaUniversity
of Padova, I-35131 Padova, Italy  T. LeCompte  Argonne National Laboratory,
Argonne, Illinois 60439, USA  E. Lee  Texas A&M University, College Station,
Texas 77843, USA  H.S. Lee  Enrico Fermi Institute, University of Chicago,
Chicago, Illinois 60637, USA  J.S. Lee  Center for High Energy Physics:
Kyungpook National University, Daegu 702-701, Korea; Seoul National
University, Seoul 151-742, Korea; Sungkyunkwan University, Suwon 440-746,
Korea; Korea Institute of Science and Technology Information, Daejeon 305-806,
Korea; Chonnam National University, Gwangju 500-757, Korea; Chonbuk National
University, Jeonju 561-756, Korea  S.W. Leew Texas A&M University, College
Station, Texas 77843, USA  S. Leobb Istituto Nazionale di Fisica Nucleare
Pisa, bbUniversity of Pisa, ccUniversity of Siena and ddScuola Normale
Superiore, I-56127 Pisa, Italy  S. Leone  Istituto Nazionale di Fisica
Nucleare Pisa, bbUniversity of Pisa, ccUniversity of Siena and ddScuola
Normale Superiore, I-56127 Pisa, Italy  J.D. Lewis  Fermi National Accelerator
Laboratory, Batavia, Illinois 60510, USA  C.-J. Lin  Ernest Orlando Lawrence
Berkeley National Laboratory, Berkeley, California 94720, USA  J. Linacre
University of Oxford, Oxford OX1 3RH, United Kingdom  M. Lindgren  Fermi
National Accelerator Laboratory, Batavia, Illinois 60510, USA  E. Lipeles
University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA  A. Lister
University of Geneva, CH-1211 Geneva 4, Switzerland  D.O. Litvintsev  Fermi
National Accelerator Laboratory, Batavia, Illinois 60510, USA  C. Liu
University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA  Q. Liu  Purdue
University, West Lafayette, Indiana 47907, USA  T. Liu  Fermi National
Accelerator Laboratory, Batavia, Illinois 60510, USA  S. Lockwitz  Yale
University, New Haven, Connecticut 06520, USA  N.S. Lockyer  University of
Pennsylvania, Philadelphia, Pennsylvania 19104, USA  A. Loginov  Yale
University, New Haven, Connecticut 06520, USA  H.K. Lou  Rutgers University,
Piscataway, New Jersey 08855, USA  D. Lucchesiaa Istituto Nazionale di Fisica
Nucleare, Sezione di Padova-Trento, aaUniversity of Padova, I-35131 Padova,
Italy  J. Lueck  Institut für Experimentelle Kernphysik, Karlsruhe Institute
of Technology, D-76131 Karlsruhe, Germany  P. Lujan  Ernest Orlando Lawrence
Berkeley National Laboratory, Berkeley, California 94720, USA  P. Lukens
Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA  G. Lungu
The Rockefeller University, New York, New York 10065, USA  J. Lys  Ernest
Orlando Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
R. Lysak  Comenius University, 842 48 Bratislava, Slovakia; Institute of
Experimental Physics, 040 01 Kosice, Slovakia  R. Madrak  Fermi National
Accelerator Laboratory, Batavia, Illinois 60510, USA  K. Maeshima  Fermi
National Accelerator Laboratory, Batavia, Illinois 60510, USA  K. Makhoul
Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA  P.
Maksimovic  The Johns Hopkins University, Baltimore, Maryland 21218, USA  S.
Malik  The Rockefeller University, New York, New York 10065, USA  G. Mancab
University of Liverpool, Liverpool L69 7ZE, United Kingdom  A. Manousakis-
Katsikakis  University of Athens, 157 71 Athens, Greece  F. Margaroli  Purdue
University, West Lafayette, Indiana 47907, USA  C. Marino  Institut für
Experimentelle Kernphysik, Karlsruhe Institute of Technology, D-76131
Karlsruhe, Germany  M. Martínez  Institut de Fisica d’Altes Energies, ICREA,
Universitat Autonoma de Barcelona, E-08193, Bellaterra (Barcelona), Spain  R.
Martínez-Ballarín  Centro de Investigaciones Energeticas Medioambientales y
Tecnologicas, E-28040 Madrid, Spain  P. Mastrandrea  Istituto Nazionale di
Fisica Nucleare, Sezione di Roma 1, eeSapienza Università di Roma, I-00185
Roma, Italy  M. Mathis  The Johns Hopkins University, Baltimore, Maryland
21218, USA  M.E. Mattson  Wayne State University, Detroit, Michigan 48201, USA
P. Mazzanti  Istituto Nazionale di Fisica Nucleare Bologna, zUniversity of
Bologna, I-40127 Bologna, Italy  K.S. McFarland  University of Rochester,
Rochester, New York 14627, USA  P. McIntyre  Texas A&M University, College
Station, Texas 77843, USA  R. McNultyi University of Liverpool, Liverpool L69
7ZE, United Kingdom  A. Mehta  University of Liverpool, Liverpool L69 7ZE,
United Kingdom  P. Mehtala  Division of High Energy Physics, Department of
Physics, University of Helsinki and Helsinki Institute of Physics, FIN-00014,
Helsinki, Finland  A. Menzione  Istituto Nazionale di Fisica Nucleare Pisa,
bbUniversity of Pisa, ccUniversity of Siena and ddScuola Normale Superiore,
I-56127 Pisa, Italy  C. Mesropian  The Rockefeller University, New York, New
York 10065, USA  T. Miao  Fermi National Accelerator Laboratory, Batavia,
Illinois 60510, USA  D. Mietlicki  University of Michigan, Ann Arbor, Michigan
48109, USA  A. Mitra  Institute of Physics, Academia Sinica, Taipei, Taiwan
11529, Republic of China  H. Miyake  University of Tsukuba, Tsukuba, Ibaraki
305, Japan  S. Moed  Harvard University, Cambridge, Massachusetts 02138, USA
N. Moggi  Istituto Nazionale di Fisica Nucleare Bologna, zUniversity of
Bologna, I-40127 Bologna, Italy  M.N. Mondragonk Fermi National Accelerator
Laboratory, Batavia, Illinois 60510, USA  C.S. Moon  Center for High Energy
Physics: Kyungpook National University, Daegu 702-701, Korea; Seoul National
University, Seoul 151-742, Korea; Sungkyunkwan University, Suwon 440-746,
Korea; Korea Institute of Science and Technology Information, Daejeon 305-806,
Korea; Chonnam National University, Gwangju 500-757, Korea; Chonbuk National
University, Jeonju 561-756, Korea  R. Moore  Fermi National Accelerator
Laboratory, Batavia, Illinois 60510, USA  M.J. Morello  Fermi National
Accelerator Laboratory, Batavia, Illinois 60510, USA  J. Morlock  Institut für
Experimentelle Kernphysik, Karlsruhe Institute of Technology, D-76131
Karlsruhe, Germany  P. Movilla Fernandez  Fermi National Accelerator
Laboratory, Batavia, Illinois 60510, USA  A. Mukherjee  Fermi National
Accelerator Laboratory, Batavia, Illinois 60510, USA  Th. Muller  Institut für
Experimentelle Kernphysik, Karlsruhe Institute of Technology, D-76131
Karlsruhe, Germany  P. Murat  Fermi National Accelerator Laboratory, Batavia,
Illinois 60510, USA  M. Mussiniz Istituto Nazionale di Fisica Nucleare
Bologna, zUniversity of Bologna, I-40127 Bologna, Italy  J. Nachtmanm Fermi
National Accelerator Laboratory, Batavia, Illinois 60510, USA  Y. Nagai
University of Tsukuba, Tsukuba, Ibaraki 305, Japan  J. Naganoma  Waseda
University, Tokyo 169, Japan  I. Nakano  Okayama University, Okayama 700-8530,
Japan  A. Napier  Tufts University, Medford, Massachusetts 02155, USA  J. Nett
Texas A&M University, College Station, Texas 77843, USA  C. Neu  University of
Virginia, Charlottesville, VA 22906, USA  M.S. Neubauer  University of
Illinois, Urbana, Illinois 61801, USA  J. Nielsene Ernest Orlando Lawrence
Berkeley National Laboratory, Berkeley, California 94720, USA  L. Nodulman
Argonne National Laboratory, Argonne, Illinois 60439, USA  O. Norniella
University of Illinois, Urbana, Illinois 61801, USA  E. Nurse  University
College London, London WC1E 6BT, United Kingdom  L. Oakes  University of
Oxford, Oxford OX1 3RH, United Kingdom  S.H. Oh  Duke University, Durham,
North Carolina 27708, USA  Y.D. Oh  Center for High Energy Physics: Kyungpook
National University, Daegu 702-701, Korea; Seoul National University, Seoul
151-742, Korea; Sungkyunkwan University, Suwon 440-746, Korea; Korea Institute
of Science and Technology Information, Daejeon 305-806, Korea; Chonnam
National University, Gwangju 500-757, Korea; Chonbuk National University,
Jeonju 561-756, Korea  I. Oksuzian  University of Virginia, Charlottesville,
VA 22906, USA  T. Okusawa  Osaka City University, Osaka 588, Japan  R. Orava
Division of High Energy Physics, Department of Physics, University of Helsinki
and Helsinki Institute of Physics, FIN-00014, Helsinki, Finland  L. Ortolan
Institut de Fisica d’Altes Energies, ICREA, Universitat Autonoma de Barcelona,
E-08193, Bellaterra (Barcelona), Spain  S. Pagan Grisoaa Istituto Nazionale di
Fisica Nucleare, Sezione di Padova-Trento, aaUniversity of Padova, I-35131
Padova, Italy  C. Pagliarone  Istituto Nazionale di Fisica Nucleare
Trieste/Udine, I-34100 Trieste, ffUniversity of Trieste/Udine, I-33100 Udine,
Italy  E. Palenciaf Instituto de Fisica de Cantabria, CSIC-University of
Cantabria, 39005 Santander, Spain  V. Papadimitriou  Fermi National
Accelerator Laboratory, Batavia, Illinois 60510, USA  A.A. Paramonov  Argonne
National Laboratory, Argonne, Illinois 60439, USA  J. Patrick  Fermi National
Accelerator Laboratory, Batavia, Illinois 60510, USA  G. Paulettaff Istituto
Nazionale di Fisica Nucleare Trieste/Udine, I-34100 Trieste, ffUniversity of
Trieste/Udine, I-33100 Udine, Italy  M. Paulini  Carnegie Mellon University,
Pittsburgh, Pennsylvania 15213, USA  C. Paus  Massachusetts Institute of
Technology, Cambridge, Massachusetts 02139, USA  D.E. Pellett  University of
California, Davis, Davis, California 95616, USA  A. Penzo  Istituto Nazionale
di Fisica Nucleare Trieste/Udine, I-34100 Trieste, ffUniversity of
Trieste/Udine, I-33100 Udine, Italy  T.J. Phillips  Duke University, Durham,
North Carolina 27708, USA  G. Piacentino  Istituto Nazionale di Fisica
Nucleare Pisa, bbUniversity of Pisa, ccUniversity of Siena and ddScuola
Normale Superiore, I-56127 Pisa, Italy  E. Pianori  University of
Pennsylvania, Philadelphia, Pennsylvania 19104, USA  J. Pilot  The Ohio State
University, Columbus, Ohio 43210, USA  K. Pitts  University of Illinois,
Urbana, Illinois 61801, USA  C. Plager  University of California, Los Angeles,
Los Angeles, California 90024, USA  L. Pondrom  University of Wisconsin,
Madison, Wisconsin 53706, USA  K. Potamianos  Purdue University, West
Lafayette, Indiana 47907, USA  O. Poukhov††footnotemark:  Joint Institute for
Nuclear Research, RU-141980 Dubna, Russia  F. Prokoshinx Joint Institute for
Nuclear Research, RU-141980 Dubna, Russia  A. Pronko  Fermi National
Accelerator Laboratory, Batavia, Illinois 60510, USA  F. Ptohosh Laboratori
Nazionali di Frascati, Istituto Nazionale di Fisica Nucleare, I-00044
Frascati, Italy  E. Pueschel  Carnegie Mellon University, Pittsburgh,
Pennsylvania 15213, USA  G. Punzibb Istituto Nazionale di Fisica Nucleare
Pisa, bbUniversity of Pisa, ccUniversity of Siena and ddScuola Normale
Superiore, I-56127 Pisa, Italy  J. Pursley  University of Wisconsin, Madison,
Wisconsin 53706, USA  A. Rahaman  University of Pittsburgh, Pittsburgh,
Pennsylvania 15260, USA  V. Ramakrishnan  University of Wisconsin, Madison,
Wisconsin 53706, USA  N. Ranjan  Purdue University, West Lafayette, Indiana
47907, USA  I. Redondo  Centro de Investigaciones Energeticas Medioambientales
y Tecnologicas, E-28040 Madrid, Spain  P. Renton  University of Oxford, Oxford
OX1 3RH, United Kingdom  M. Rescigno  Istituto Nazionale di Fisica Nucleare,
Sezione di Roma 1, eeSapienza Università di Roma, I-00185 Roma, Italy  F.
Rimondiz Istituto Nazionale di Fisica Nucleare Bologna, zUniversity of
Bologna, I-40127 Bologna, Italy  L. Ristori45 Fermi National Accelerator
Laboratory, Batavia, Illinois 60510, USA  A. Robson  Glasgow University,
Glasgow G12 8QQ, United Kingdom  T. Rodrigo  Instituto de Fisica de Cantabria,
CSIC-University of Cantabria, 39005 Santander, Spain  T. Rodriguez  University
of Pennsylvania, Philadelphia, Pennsylvania 19104, USA  E. Rogers  University
of Illinois, Urbana, Illinois 61801, USA  S. Rolli  Tufts University, Medford,
Massachusetts 02155, USA  R. Roser  Fermi National Accelerator Laboratory,
Batavia, Illinois 60510, USA  M. Rossi  Istituto Nazionale di Fisica Nucleare
Trieste/Udine, I-34100 Trieste, ffUniversity of Trieste/Udine, I-33100 Udine,
Italy  F. Rubbo  Fermi National Accelerator Laboratory, Batavia, Illinois
60510, USA  F. Ruffinicc Istituto Nazionale di Fisica Nucleare Pisa,
bbUniversity of Pisa, ccUniversity of Siena and ddScuola Normale Superiore,
I-56127 Pisa, Italy  A. Ruiz  Instituto de Fisica de Cantabria, CSIC-
University of Cantabria, 39005 Santander, Spain  J. Russ  Carnegie Mellon
University, Pittsburgh, Pennsylvania 15213, USA  V. Rusu  Fermi National
Accelerator Laboratory, Batavia, Illinois 60510, USA  A. Safonov  Texas A&M
University, College Station, Texas 77843, USA  W.K. Sakumoto  University of
Rochester, Rochester, New York 14627, USA  Y. Sakurai  Waseda University,
Tokyo 169, Japan  L. Santiff Istituto Nazionale di Fisica Nucleare
Trieste/Udine, I-34100 Trieste, ffUniversity of Trieste/Udine, I-33100 Udine,
Italy  L. Sartori  Istituto Nazionale di Fisica Nucleare Pisa, bbUniversity of
Pisa, ccUniversity of Siena and ddScuola Normale Superiore, I-56127 Pisa,
Italy  K. Sato  University of Tsukuba, Tsukuba, Ibaraki 305, Japan  V.
Savelievt LPNHE, Universite Pierre et Marie Curie/IN2P3-CNRS, UMR7585, Paris,
F-75252 France  A. Savoy-Navarro  LPNHE, Universite Pierre et Marie
Curie/IN2P3-CNRS, UMR7585, Paris, F-75252 France  P. Schlabach  Fermi National
Accelerator Laboratory, Batavia, Illinois 60510, USA  A. Schmidt  Institut für
Experimentelle Kernphysik, Karlsruhe Institute of Technology, D-76131
Karlsruhe, Germany  E.E. Schmidt  Fermi National Accelerator Laboratory,
Batavia, Illinois 60510, USA  M.P. Schmidt††footnotemark:  Yale University,
New Haven, Connecticut 06520, USA  M. Schmitt  Northwestern University,
Evanston, Illinois 60208, USA  T. Schwarz  University of California, Davis,
Davis, California 95616, USA  L. Scodellaro  Instituto de Fisica de Cantabria,
CSIC-University of Cantabria, 39005 Santander, Spain  A. Scribanocc Istituto
Nazionale di Fisica Nucleare Pisa, bbUniversity of Pisa, ccUniversity of Siena
and ddScuola Normale Superiore, I-56127 Pisa, Italy  F. Scuri  Istituto
Nazionale di Fisica Nucleare Pisa, bbUniversity of Pisa, ccUniversity of Siena
and ddScuola Normale Superiore, I-56127 Pisa, Italy  A. Sedov  Purdue
University, West Lafayette, Indiana 47907, USA  S. Seidel  University of New
Mexico, Albuquerque, New Mexico 87131, USA  C. Seitz  Rutgers University,
Piscataway, New Jersey 08855, USA  Y. Seiya  Osaka City University, Osaka 588,
Japan  A. Semenov  Joint Institute for Nuclear Research, RU-141980 Dubna,
Russia  F. Sforzabb Istituto Nazionale di Fisica Nucleare Pisa, bbUniversity
of Pisa, ccUniversity of Siena and ddScuola Normale Superiore, I-56127 Pisa,
Italy  A. Sfyrla  University of Illinois, Urbana, Illinois 61801, USA  S.Z.
Shalhout  University of California, Davis, Davis, California 95616, USA  T.
Shears  University of Liverpool, Liverpool L69 7ZE, United Kingdom  P.F.
Shepard  University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA  M.
Shimojimas University of Tsukuba, Tsukuba, Ibaraki 305, Japan  S. Shiraishi
Enrico Fermi Institute, University of Chicago, Chicago, Illinois 60637, USA
M. Shochet  Enrico Fermi Institute, University of Chicago, Chicago, Illinois
60637, USA  I. Shreyber  Institution for Theoretical and Experimental Physics,
ITEP, Moscow 117259, Russia  A. Simonenko  Joint Institute for Nuclear
Research, RU-141980 Dubna, Russia  P. Sinervo  Institute of Particle Physics:
McGill University, Montréal, Québec, Canada H3A 2T8; Simon Fraser University,
Burnaby, British Columbia, Canada V5A 1S6; University of Toronto, Toronto,
Ontario, Canada M5S 1A7; and TRIUMF, Vancouver, British Columbia, Canada V6T
2A3  A. Sissakian††footnotemark:  Joint Institute for Nuclear Research,
RU-141980 Dubna, Russia  K. Sliwa  Tufts University, Medford, Massachusetts
02155, USA  J.R. Smith  University of California, Davis, Davis, California
95616, USA  F.D. Snider  Fermi National Accelerator Laboratory, Batavia,
Illinois 60510, USA  A. Soha  Fermi National Accelerator Laboratory, Batavia,
Illinois 60510, USA  S. Somalwar  Rutgers University, Piscataway, New Jersey
08855, USA  V. Sorin  Institut de Fisica d’Altes Energies, ICREA, Universitat
Autonoma de Barcelona, E-08193, Bellaterra (Barcelona), Spain  P. Squillacioti
Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA  M.
Stancari  Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA
M. Stanitzki  Yale University, New Haven, Connecticut 06520, USA  R. St. Denis
Glasgow University, Glasgow G12 8QQ, United Kingdom  B. Stelzer  Institute of
Particle Physics: McGill University, Montréal, Québec, Canada H3A 2T8; Simon
Fraser University, Burnaby, British Columbia, Canada V5A 1S6; University of
Toronto, Toronto, Ontario, Canada M5S 1A7; and TRIUMF, Vancouver, British
Columbia, Canada V6T 2A3  O. Stelzer-Chilton  Institute of Particle Physics:
McGill University, Montréal, Québec, Canada H3A 2T8; Simon Fraser University,
Burnaby, British Columbia, Canada V5A 1S6; University of Toronto, Toronto,
Ontario, Canada M5S 1A7; and TRIUMF, Vancouver, British Columbia, Canada V6T
2A3  D. Stentz  Northwestern University, Evanston, Illinois 60208, USA  J.
Strologas  University of New Mexico, Albuquerque, New Mexico 87131, USA  G.L.
Strycker  University of Michigan, Ann Arbor, Michigan 48109, USA  Y. Sudo
University of Tsukuba, Tsukuba, Ibaraki 305, Japan  A. Sukhanov  University of
Florida, Gainesville, Florida 32611, USA  I. Suslov  Joint Institute for
Nuclear Research, RU-141980 Dubna, Russia  K. Takemasa  University of Tsukuba,
Tsukuba, Ibaraki 305, Japan  Y. Takeuchi  University of Tsukuba, Tsukuba,
Ibaraki 305, Japan  J. Tang  Enrico Fermi Institute, University of Chicago,
Chicago, Illinois 60637, USA  M. Tecchio  University of Michigan, Ann Arbor,
Michigan 48109, USA  P.K. Teng  Institute of Physics, Academia Sinica, Taipei,
Taiwan 11529, Republic of China  J. Thomg Fermi National Accelerator
Laboratory, Batavia, Illinois 60510, USA  S. Thomas  Rutgers University,
Piscataway, New Jersey 08855, USA  J. Thome  Carnegie Mellon University,
Pittsburgh, Pennsylvania 15213, USA  G.A. Thompson  University of Illinois,
Urbana, Illinois 61801, USA  E. Thomson  University of Pennsylvania,
Philadelphia, Pennsylvania 19104, USA  P. Ttito-Guzmán  Centro de
Investigaciones Energeticas Medioambientales y Tecnologicas, E-28040 Madrid,
Spain  S. Tkaczyk  Fermi National Accelerator Laboratory, Batavia, Illinois
60510, USA  D. Toback  Texas A&M University, College Station, Texas 77843, USA
S. Tokar  Comenius University, 842 48 Bratislava, Slovakia; Institute of
Experimental Physics, 040 01 Kosice, Slovakia  K. Tollefson  Michigan State
University, East Lansing, Michigan 48824, USA  T. Tomura  University of
Tsukuba, Tsukuba, Ibaraki 305, Japan  D. Tonelli  Fermi National Accelerator
Laboratory, Batavia, Illinois 60510, USA  S. Torre  Laboratori Nazionali di
Frascati, Istituto Nazionale di Fisica Nucleare, I-00044 Frascati, Italy  D.
Torretta  Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA
P. Totaroff Istituto Nazionale di Fisica Nucleare Trieste/Udine, I-34100
Trieste, ffUniversity of Trieste/Udine, I-33100 Udine, Italy  M. Trovatodd
Istituto Nazionale di Fisica Nucleare Pisa, bbUniversity of Pisa, ccUniversity
of Siena and ddScuola Normale Superiore, I-56127 Pisa, Italy  Y. Tu
University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA  F. Ukegawa
University of Tsukuba, Tsukuba, Ibaraki 305, Japan  S. Uozumi  Center for High
Energy Physics: Kyungpook National University, Daegu 702-701, Korea; Seoul
National University, Seoul 151-742, Korea; Sungkyunkwan University, Suwon
440-746, Korea; Korea Institute of Science and Technology Information, Daejeon
305-806, Korea; Chonnam National University, Gwangju 500-757, Korea; Chonbuk
National University, Jeonju 561-756, Korea  A. Varganov  University of
Michigan, Ann Arbor, Michigan 48109, USA  F. Vázquezk University of Florida,
Gainesville, Florida 32611, USA  G. Velev  Fermi National Accelerator
Laboratory, Batavia, Illinois 60510, USA  C. Vellidis  University of Athens,
157 71 Athens, Greece  M. Vidal  Centro de Investigaciones Energeticas
Medioambientales y Tecnologicas, E-28040 Madrid, Spain  I. Vila  Instituto de
Fisica de Cantabria, CSIC-University of Cantabria, 39005 Santander, Spain  R.
Vilar  Instituto de Fisica de Cantabria, CSIC-University of Cantabria, 39005
Santander, Spain  J. Vizán  Instituto de Fisica de Cantabria, CSIC-University
of Cantabria, 39005 Santander, Spain  M. Vogel  University of New Mexico,
Albuquerque, New Mexico 87131, USA  G. Volpibb Istituto Nazionale di Fisica
Nucleare Pisa, bbUniversity of Pisa, ccUniversity of Siena and ddScuola
Normale Superiore, I-56127 Pisa, Italy  P. Wagner  University of Pennsylvania,
Philadelphia, Pennsylvania 19104, USA  R.L. Wagner  Fermi National Accelerator
Laboratory, Batavia, Illinois 60510, USA  T. Wakisaka  Osaka City University,
Osaka 588, Japan  R. Wallny  University of California, Los Angeles, Los
Angeles, California 90024, USA  S.M. Wang  Institute of Physics, Academia
Sinica, Taipei, Taiwan 11529, Republic of China  A. Warburton  Institute of
Particle Physics: McGill University, Montréal, Québec, Canada H3A 2T8; Simon
Fraser University, Burnaby, British Columbia, Canada V5A 1S6; University of
Toronto, Toronto, Ontario, Canada M5S 1A7; and TRIUMF, Vancouver, British
Columbia, Canada V6T 2A3  D. Waters  University College London, London WC1E
6BT, United Kingdom  M. Weinberger  Texas A&M University, College Station,
Texas 77843, USA  W.C. Wester III  Fermi National Accelerator Laboratory,
Batavia, Illinois 60510, USA  B. Whitehouse  Tufts University, Medford,
Massachusetts 02155, USA  D. Whitesonc University of Pennsylvania,
Philadelphia, Pennsylvania 19104, USA  A.B. Wicklund  Argonne National
Laboratory, Argonne, Illinois 60439, USA  E. Wicklund  Fermi National
Accelerator Laboratory, Batavia, Illinois 60510, USA  S. Wilbur  Enrico Fermi
Institute, University of Chicago, Chicago, Illinois 60637, USA  F. Wick
Institut für Experimentelle Kernphysik, Karlsruhe Institute of Technology,
D-76131 Karlsruhe, Germany  H.H. Williams  University of Pennsylvania,
Philadelphia, Pennsylvania 19104, USA  J.S. Wilson  The Ohio State University,
Columbus, Ohio 43210, USA  P. Wilson  Fermi National Accelerator Laboratory,
Batavia, Illinois 60510, USA  B.L. Winer  The Ohio State University, Columbus,
Ohio 43210, USA  P. Wittichg Fermi National Accelerator Laboratory, Batavia,
Illinois 60510, USA  S. Wolbers  Fermi National Accelerator Laboratory,
Batavia, Illinois 60510, USA  H. Wolfe  The Ohio State University, Columbus,
Ohio 43210, USA  T. Wright  University of Michigan, Ann Arbor, Michigan 48109,
USA  X. Wu  University of Geneva, CH-1211 Geneva 4, Switzerland  Z. Wu  Baylor
University, Waco, Texas 76798, USA  K. Yamamoto  Osaka City University, Osaka
588, Japan  J. Yamaoka  Duke University, Durham, North Carolina 27708, USA  T.
Yang  Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA
U.K. Yangp Enrico Fermi Institute, University of Chicago, Chicago, Illinois
60637, USA  Y.C. Yang  Center for High Energy Physics: Kyungpook National
University, Daegu 702-701, Korea; Seoul National University, Seoul 151-742,
Korea; Sungkyunkwan University, Suwon 440-746, Korea; Korea Institute of
Science and Technology Information, Daejeon 305-806, Korea; Chonnam National
University, Gwangju 500-757, Korea; Chonbuk National University, Jeonju
561-756, Korea  W.-M. Yao  Ernest Orlando Lawrence Berkeley National
Laboratory, Berkeley, California 94720, USA  G.P. Yeh  Fermi National
Accelerator Laboratory, Batavia, Illinois 60510, USA  K. Yim Fermi National
Accelerator Laboratory, Batavia, Illinois 60510, USA  J. Yoh  Fermi National
Accelerator Laboratory, Batavia, Illinois 60510, USA  K. Yorita  Waseda
University, Tokyo 169, Japan  T. Yoshidaj Osaka City University, Osaka 588,
Japan  G.B. Yu  Duke University, Durham, North Carolina 27708, USA  I. Yu
Center for High Energy Physics: Kyungpook National University, Daegu 702-701,
Korea; Seoul National University, Seoul 151-742, Korea; Sungkyunkwan
University, Suwon 440-746, Korea; Korea Institute of Science and Technology
Information, Daejeon 305-806, Korea; Chonnam National University, Gwangju
500-757, Korea; Chonbuk National University, Jeonju 561-756, Korea  S.S. Yu
Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA  J.C. Yun
Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA  A.
Zanetti  Istituto Nazionale di Fisica Nucleare Trieste/Udine, I-34100 Trieste,
ffUniversity of Trieste/Udine, I-33100 Udine, Italy  Y. Zeng  Duke University,
Durham, North Carolina 27708, USA  S. Zucchelliz Istituto Nazionale di Fisica
Nucleare Bologna, zUniversity of Bologna, I-40127 Bologna, Italy

###### Abstract

We present the first model independent search for three-jet hadronic
resonances within multijet events in $\sqrt{s}=1.96$ TeV $p\bar{p}$ collisions
at the Fermilab Tevatron using the CDF II detector. Pair production of
supersymmetric gluinos and squarks with hadronic R-parity violating decays is
employed as an example of a new physics benchmark for this signature.
Selection criteria based on the kinematic properties of an ensemble of jet
combinations within each event help to extract signal from copious QCD
background. Our background estimates include all-hadronic $t\bar{t}$ decays
that have a signature similar to the signal. No significant excess outside the
top quark mass window is observed in data with an integrated luminosity of 3.2
fb-1. We place 95% confidence level limits on the production cross section
$\sigma(p\bar{p}\rightarrow
XX^{{}^{\prime}})\times\rm{BR}$($\widetilde{g}\widetilde{g}$$\rightarrow
3~{}{\rm jet}+3~{}{\rm jet})$ where
$X,X^{\prime}=\widetilde{g},~{}\widetilde{q}$, or $\widetilde{\bar{q}}$, with
$\widetilde{q}$, $\widetilde{\bar{q}}\rightarrow\widetilde{g}$ \+ jet, as a
function of gluino mass, in the range of 77 GeV/$c^{2}$ to 240 GeV/$c^{2}$.

###### pacs:

13.85.-t, 11.30.Pb

Most searches for new physics at high energy hadron colliders use signatures
that require leptons, photons, or missing transverse energy
(${\not\\!\\!E_{\rm T}}$) bib (a) in order to suppress backgrounds from QCD.
Final states with multijets and ${\not\\!\\!E_{\rm T}}$ have also been
explored Aaltonen et al. (2009a); Abazov et al. (2008).

In this letter, we present a first new physics search in an entirely hadronic
channel with no ${\not\\!\\!E_{\rm T}}$ signature using data collected with
the Collider Detector at Fermilab (CDF). This data set corresponds to an
integrated luminosity of 3.2 fb-1 of $p\bar{p}$ collisions at $\sqrt{s}=1.96$
TeV at the Tevatron collider. The search utilizes a novel approach Essig ;
Seitz : an ensemble of all possible jet triplets within an event consisting of
at least six jets is used to extract a signal from the multijet QCD
backgrounds. We model the possible new physics origin for this signature with
pair production of $SU(3)_{C}$ adjoint Majorana fermions each one decaying
into three quarks R. Chivukula, M. Golden, and E. Simmons (1991a, b). This
search is sensitive to models such as hadronic R-parity violating
supersymmetry (RPV SUSY) Essig  with a gluino, chargino, or neutralino
lightest superpartner, as well as the hadronic decay modes of pairs of top
quarks or fourth generation quarks and it complements existing di-jet
resonances searches at hadron colliders. Moreover, it does not require any
$b$-quark jet identification which is an important tool, often used for top
quark identification.

The CDF II detector is a multi-purpose particle detector consisting of
tracking and calorimeter systems Abulencia et al. (2007). The data were
collected using an online event selection that requires at least four
calorimeter jets Aaltonen et al. (2009b) with uncorrected transverse energy
$E_{T}>$ 15 GeV. A jet is formed by a cluster of calorimeter towers and
reconstructed with a cone algorithm using a fixed cone of $\Delta R=0.4$ Abe
et al. (1992), with $\Delta R=\sqrt{\Delta\eta^{2}+\Delta\phi^{2}}$ bib (a).
In the online selection an additional request is made for the sum of the
transverse energy of all clusters to be larger than 175 GeV. At the analysis
level, jet energies are corrected to account for effects such as non-
linearities in the detector response and multiple $p\bar{p}$ collisions in an
event Bhatti et al. (2006).

Events are selected with at least six jets with transverse momentum ($p_{T}$)
greater than 15 GeV/$c$ and $|\eta|<2.5$. The scalar sum of the most energetic
six jets’ $p_{T}$, $\sum p_{T}$, is required to be greater than 250 GeV/$c$
and events with $\mbox{${\not\\!\\!E_{\rm T}}$}>50$ GeV are removed. Multiple
interactions, resulting in the reconstruction of more than one primary vertex
in the same event, contribute to the multijet background. We require at least
one primary vertex and discard events with more than four primary vertices. To
further reduce this background, we require jets in an event to originate from
near the same point on the beamline. We associate tracks with each jet where
possible bib (b) by requiring $\Delta R$ between the track and the jet to be
less than 0.4. The mean $z$-coordinate of all tracks associated with each jet
($\bar{z_{j}}$ for the $j^{\rm th}$ jet), and the associated standard
deviation ($\delta(z_{j})$) are determined. Events with jets that have
$|\bar{z_{j}}|>60$ cm are discarded. We then evaluate the standard deviation
of the $\bar{z_{j}}$ of all jets in the event ($\delta(z_{\textrm{all}}$)) and
select events that have at least four jets with $\delta(z_{j})<4$ cm, and
$\delta(z_{\textrm{all}})<0.5$ cm, consistent with the resolution of tracks
associated with jets. Once the selection is applied, pileup effects are
significantly reduced. Since we select events with at least six jets, we
consider an ensemble of 20 (or more) possible jet triplets. We discard those
triplets that have more than one jet with no $z$ information. In addition, all
jets in the triplet must have $\delta(z_{j})<2.5$ cm, and originate from
within 10 cm of the primary vertex of the event.

The biggest challenge of this analysis is to reduce the large multijet QCD
background. To extract signal from this background, we apply the following
technique: for every accepted triplet we calculate the invariant mass,
$M_{jjj}$, and scalar sum $p_{T}$, $\sum_{jjj}p_{T}$. Triplets made of
uncorrelated jets tend to have $M_{jjj}c\approx\sum_{jjj}p_{T}$, while signal
triplets should have $M_{jjj}$ as close to the mass of the decaying particle
as allowed by jet energy resolution. We then select triplets with
$\sum_{jjj}p_{T}-M_{jjj}c>\Delta$, $\Delta$ being a diagonal offset as
illustrated in Fig. 1. The diagonal offset values are optimized for the best
signal over background ratio separately for each hadronic resonance mass in
this search. The optimized diagonal offset selection greatly reduces the QCD
background and the contribution from incorrect combinations of jets. We note
that for a small fraction of events it is possible for multiple triplets to
pass all selection criteria.

Figure 1: Distribution of $M_{jjj}$ versus $\sum_{jjj}p_{T}$ for a pair-
produced RPV gluino with invariant mass 190 GeV/c2 generated with pythia MC.
Triplets to the right of a diagonal offset
($\sum_{jjj}p_{T}-M_{jjj}c=\Delta$), indicated by the dashed line, are are
kept. The inset shows the $M_{jjj}$ distribution for the RPV signal MC and
with no QCD background after a diagonal offset of 195 GeV/$c$ along with a
Gaussian plus a Landau fit; the Landau shows the combinatorial contribution
within the signal jet ensemble. The QCD background distribution resembles that
of the combinatorial contribution, because they are both due to effectively
uncorrelated triplets.

The QCD background is estimated from a 5-jet data sample, which is
statistically independent of the signal sample of $\geq 6$ jets (for brevity
referred to as 6-jet). The 5-jet $M_{jjj}$ distribution is rescaled by the
ratio of the 6-jet to 5-jet population in each $\sum_{jjj}{p_{T}}$ bin. A
Landau function is chosen Essig  to fit the scaled 5-jet $M_{jjj}$
distribution. The Landau parameters extracted from the scaled 5-jet $M_{jjj}$
distribution vary by less than 2 GeV/$c^{2}$ from similar fits to the 6-jet
sample, indicating that the scaled 5-jet sample describes the background in
the 6-jet sample well. The contribution to the background from $t\bar{t}$ pair
production is estimated using the pythia Monte Carlo (MC) generator Sjöstrand
et al. (2001) followed by the CDF detector simulation bib (2003). These events
were generated assuming a top quark mass of 172.5 GeV/$c^{2}$ and production
cross section of 7.5 pb. To ensure a proper fit to the QCD background, the fit
is blinded to the mass region corresponding to the top quark, 153
GeV/$c^{2}$$<M_{jjj}<$189 GeV/$c^{2}$. Additionally, we find that truncating
the Landau fit for lower values of $\Delta$ gives an improved description of
the QCD background. The Landau parameters extracted from the fits vary
smoothly as functions of the diagonal offset value. We now have a firm
prediction for the QCD background and fix the parameters when we fit for
signal.

The signal is modeled using the pythia MC generator. The process
$p\bar{p}\rightarrow XX^{{}^{\prime}}$ where
$X,X^{\prime}=\widetilde{g},~{}\widetilde{q}$, or $\widetilde{\bar{q}}$ is
simulated at several gluino mass values, ranging from 74 GeV/$c^{2}$ to 245
GeV/$c^{2}$ with hadronic $uds$ RPV SUSY decays turned on, allowing gluino
decays to three light jets. Two scenarios of squark masses are considered
($0.5$ TeV/$c^{2}$ $<m_{\widetilde{q}}<0.7$ TeV/$c^{2}$,
$m_{\widetilde{q}}=m_{\widetilde{g}}+10$ GeV/$c^{2}$) and were found to give
equivalent acceptances.

The acceptance of the trigger, reconstruction, and selection requirements for
signal events is determined by fitting the pair produced RPV gluino MC with a
Landau plus Gaussian function, corresponding to the combinatorial contribution
and signal peak respectively. An example is shown in the inset of Fig. 1. The
Gaussian is integrated in a $\pm 1\sigma$ range to extract the number of
signal triplets. This procedure is repeated for various diagonal offset values
and the optimal offset for each hadronic resonance mass is determined. The
acceptance, calculated for these optimal offset values, is $5\times 10^{-5}$,
constant within 20% across all gluino mass points.

The expected sensitivity of this analysis in the absence of signal is
determined with a set of background-only experiments (pseudoexperiments). A
pseudoexperiment is constructed with the background modeled by a Landau
function whose parameters are chosen randomly from within the range allowed by
the background shape fits, with the expected amount of $t\bar{t}$ added. Each
pseudoexperiment is fit with the Landau background shape parameters fixed, and
a signal Gaussian whose position is determined by the mass point being fit,
and whose amplitude and width are allowed to vary within a range determined by
the expected signal shape. The number of signal triplets allowed by each
pseudoexperiment is extracted by integrating the Gaussian in the same way as
in the acceptance calculation.

Two broad categories of systematic uncertainties are accounted for in
extracting a cross section: uncertainties in the shape of the $M_{jjj}$
distribution and uncertainties in the acceptance of the signal. Shape
uncertainties, determined from background and signal fits, are incorporated in
the pseudoexperiments themselves. Acceptance uncertainties arise from modeling
the signal Monte Carlo and include effects of initial and final state
radiation Abulencia et al. (2006) (20%), parton distribution functions (PDFs)
from CTEQ Pumplin et al. (2002) (10%), jet energy scale Bhatti et al. (2006)
(31%) and luminosity Acosta et al. (2002) (6%) uncertainties. The overall
acceptance uncertainty due to these sources is 38%.

We search for a hadronic resonance in the data for an invariant mass ($m$) 77
– 240 GeV/$c^{2}$ in 9 GeV/$c^{2}$ steps, consistent with jet energy
resolution. For each mass, jet triplets are selected by the optimal diagonal
offset value. The data $M_{jjj}$ distribution is fit in exactly the same way
as the pseudoexperiments. Figure 2 shows the $M_{jjj}$ distribution for $m$ =
112 GeV/$c^{2}$ and 175 GeV/$c^{2}$. The latter fit shows a noticeable excess
consistent in mass with the hadronic decay of the top quark. The Gaussian
component of the fit integrated from 165 GeV/$c^{2}$ to 185 GeV/$c^{2}$,
corresponding to a $\pm 1\sigma$ window around the Gaussian peak, gives $11\pm
5$ triplets. The number of expected QCD background triplets in the same mass
window from the Landau function is $8\pm 1$. The $t\bar{t}$ contribution to
background is evaluated using pythia. It is cross-checked with higher order
$t\bar{t}$ MC generators alpgen Mangano et al. (2003) and mc@nlo Frixione and
Webber (2002), samples that varied the amount of initial and final state
radiation, as well as samples that varied the PDFs within their uncertainties.
These studies lead us to expect between 0.5 and 1.1 triplets from $t\bar{t}$
production in the aforementioned mass range. We note that $\sim$10% of the
triplets in the top mass window originate from two or more combinations in a
jet ensemble of a given event, consistent with the pythia $t\bar{t}$
simulation. We evaluate the significance of the excess using the
pseudoexperiment method described above, which includes systematic
uncertainties on signal acceptance as well as the shape of the $M_{jjj}$
distribution. The observed excess is 2 standard deviations (2$\sigma$) above
the prediction. Additional cross-checks, such as requiring one of the jets to
have originated from a $b$-quark, suggest that the excess is consistent with
coming from top quarks.

Figure 2: $M_{jjj}$ distributions in 3.2 fb-1 data fitted to a Landau
(parameters are extracted from fits to the scaled 5-jet $M_{jjj}$
distribution) plus a Gaussian at (a) 112 GeV/$c^{2}$ (optimal diagonal offset
value 155 GeV/$c$) and (b) 175 GeV/$c^{2}$ (optimal diagonal offset value of
190 GeV/$c$). The fit function in panel (b) includes a Gaussian fixed at
$m=175$ GeV/$c^{2}$.

We do not observe a significant deviation from standard model backgrounds
anywhere in the data. A Bayesian approach is used to place 95% confidence
level limits on $\sigma(p\bar{p}\rightarrow
XX^{{}^{\prime}})\times\rm{BR}$($\widetilde{g}\widetilde{g}$$\rightarrow
3~{}{\rm jet}+3~{}{\rm jet})$ where
$X,X^{\prime}=\widetilde{g},~{}\widetilde{q}$, or $\widetilde{\bar{q}}$, with
$\widetilde{q}$, $\widetilde{\bar{q}}\rightarrow\widetilde{g}$ \+ jet, versus
gluino mass, shown in Fig. 3. The largest excess observed is the one
previously noted located near the top quark mass. We find that our background
estimate has a 2.3% probability of producing such a deviation. Comparisons to
the theoretical cross section for $\sigma(p\bar{p}\rightarrow
XX^{{}^{\prime}})\times\rm{BR}$($\widetilde{g}\widetilde{g}$$\rightarrow
3~{}\rm{jet}+3~{}\rm{jet})$ from pythia corrected by a next-to-leading-order
(NLO) $k$-factor calculated using prospino W. Beenakker, R. Hoepker, and M.
Spira  are shown in the dashed and dash-dot lines for two different squark
mass scenarios. For a decoupled squark mass ($0.5$ TeV/$c^{2}$
$<m_{\widetilde{q}}<0.7$ TeV/$c^{2}$) we exclude gluinos below a mass of 144
GeV/$c^{2}$ (dashed line). In the case of a squark mass which is nearly
degenerate with the gluino mass ($m_{\widetilde{q}}=m_{\widetilde{g}}+10$
GeV/$c^{2}$) we exclude gluinos below 155 GeV/$c^{2}$ (dash-dot line).

We have performed a first search for three-jet hadronic resonances in a six or
more jet final state using a data sample with an integrated luminosity of 3.2
fb-1 collected by the CDF II detector. A novel technique is introduced that
exploits kinematic features within an ensemble of jet combinations that allows
us to extract signal from the QCD background. We observe no significant excess
in the data in an invariant mass range from 77 GeV/$c^{2}$ to 240 GeV/$c^{2}$
and place 95% confidence level limits on the production cross section
$\sigma(p\bar{p}\rightarrow
XX^{{}^{\prime}})\times\rm{BR}$($\widetilde{g}\widetilde{g}$$\rightarrow
3~{}{\rm jet}+3~{}{\rm jet})$ where
$X,X^{\prime}=\widetilde{g},~{}\widetilde{q}$, or $\widetilde{\bar{q}}$, with
$\widetilde{q}$, $\widetilde{\bar{q}}\rightarrow\widetilde{g}$ \+ jet, versus
gluino mass. The results are presented as limits on RPV gluinos decaying to
three jets, but are more widely applicable to any new particle with a three-
jet decay mode. Two different squark mass scenarios have been considered:
decoupled squarks and squarks nearly degenerate in mass with the gluino. We
can exclude gluinos below 144 GeV/$c^{2}$ and 155 GeV/$c^{2}$ respectively.

Figure 3: The observed (points) and expected (solid black line) 95% confidence
level limits on the production cross section $\sigma(p\bar{p}\rightarrow
XX^{{}^{\prime}})\times\rm{BR}$($\widetilde{g}\widetilde{g}\rightarrow
3~{}{\rm jet}+3~{}{\rm jet}$) where
$X,X^{\prime}=\widetilde{g},~{}\widetilde{q}$, or $\widetilde{\bar{q}}$,
including systematic uncertainties. The shaded bands represent the total
uncertainty on the limit. Also shown is the model cross section from pythia
corrected by an NLO $k$-factor (dash-dot line for $0.5$ TeV/$c^{2}$
$<m_{\widetilde{q}}<0.7$ TeV/$c^{2}$, dashed line for
$m_{\widetilde{q}}=m_{\widetilde{g}}+10$ GeV/$c^{2}$).

###### Acknowledgements.

We thank R. Essig, S. Mrenna, M. Park, and Y. Zhao for assistance with this
analysis. We also thank the Fermilab staff and the technical staffs of the
participating institutions for their vital contributions. This work was
supported by the U.S. Department of Energy and National Science Foundation;
the Italian Istituto Nazionale di Fisica Nucleare; the Ministry of Education,
Culture, Sports, Science and Technology of Japan; the Natural Sciences and
Engineering Research Council of Canada; the National Science Council of the
Republic of China; the Swiss National Science Foundation; the A.P. Sloan
Foundation; the Bundesministerium für Bildung und Forschung, Germany; the
Korean World Class University Program, the National Research Foundation of
Korea; the Science and Technology Facilities Council and the Royal Society,
UK; the Institut National de Physique Nucleaire et Physique des
Particules/CNRS; the Russian Foundation for Basic Research; the Ministerio de
Ciencia e Innovación, and Programa Consolider-Ingenio 2010, Spain; the Slovak
R&D Agency; and the Academy of Finland.

## References

  * bib (a) CDF uses a ($z$, $\phi$, $\theta$) coordinate system with the $z$-axis in the direction of the proton beam; $\phi$ and $\theta$ are the azimuthal and polar angle respectively. The pseudorapidity is defined as $\eta=-\ln(\tan{\theta\over 2})$, and the transverse momentum and energy as $p_{\rm T}=p\sin\theta$ and $E_{\rm T}=E\sin\theta$, respectively. Missing transverse energy ($\mbox{${\not\\!\\!E_{\rm T}}$}=|\mbox{${\not\\!\\!\vec{E}_{\rm T}}$}|$) is defined as $\mbox{${\not\\!\\!\vec{E}_{\rm T}}$}=-\sum_{i}E_{\rm T}^{i}{\bf{\hat{n}_{i}}}$ where ${\bf{\hat{n}_{i}}}$ is a unit vector in the transverse plane that points from the beam-line to the $i^{th}$ calorimeter tower.
  * Aaltonen et al. (2009a) T. Aaltonen et al. (CDF Collaboration), Phys. Rev. Lett. 102, 121801 (2009a).
  * Abazov et al. (2008) V. M. Abazov et al. (D0 Collaboration), Phys. Lett. B 660, 449 (2008).
  * (4) R. Essig, Ph.D. thesis, Rutgers University, 2008\.
  * (5) C. Seitz, Masters thesis, Rutgers University, 2011, FERMILAB-MASTERS-2011-01.
  * R. Chivukula, M. Golden, and E. Simmons (1991a) R. Chivukula, M. Golden, and E. Simmons, Phys. Lett. B257, 403 (1991a).
  * R. Chivukula, M. Golden, and E. Simmons (1991b) R. Chivukula, M. Golden, and E. Simmons, Nucl. Phys. B363, 83 (1991b).
  * Abulencia et al. (2007) A. Abulencia et al. (CDF Collaboration), J. Phys. G: Nucl. Part. Phys. 34, 245 (2007).
  * Aaltonen et al. (2009b) T. Aaltonen et al. (CDF Collaboration), Phys. Rev. Lett. 103, 221801 (2009b).
  * Abe et al. (1992) F. Abe et al. (CDF Collaboration), Phys. Rev. D 45, 1448 (1992).
  * Bhatti et al. (2006) A. Bhatti et al., Nucl. Instrum. Methods A 566, 375 (2006).
  * bib (b) Note that tracking efficiency drops significantly beyond $|\eta|>1.0$. Jets at large $|\eta|$ do not have associated tracks and have only limited $z$ information.
  * Sjöstrand et al. (2001) T. Sjöstrand et al., Comp. Phys. Comm. 135, 238 (2001).
  * bib (2003) Nucl. Instrum. Methods A 506, 250 (2003).
  * Abulencia et al. (2006) A. Abulencia et al. (CDF Collaboration), Phys. Rev. D 73, 032003 (2006).
  * Pumplin et al. (2002) J. Pumplin et al., Nucl. Instrum. Methods A 447, 1 (2002).
  * Acosta et al. (2002) D. Acosta et al., Nucl. Instrum. Methods A 494, 57 (2002).
  * Mangano et al. (2003) M. L. Mangano et al., J. High Energy Phys. 07 , 001 (2003).
  * Frixione and Webber (2002) S. Frixione and B. Webber, J. High Energy Phys. 06 , 029 (2002).
  * (20) W. Beenakker, R. Hoepker, and M. Spira, “PROSPINO: A Program for the Production of Supersymmetric Particles In Next-to-leading Order QCD,” arXiv:hep-ph/9611232.