Measurement of the Top-Quark Mass in All-Hadronic Decays in <em>pp</em> Collisions at CDF II

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Reference

Measurement of the Top-Quark Mass in All-Hadronic Decays in pp Collisions at CDF II

CDF Collaboration

CAMPANELLI, Mario (Collab.), et al.

Abstract

We present a measurement of the top-quark mass Mtop in the all-hadronic decay channel tt→W+bW−b→q1q2bq3q4b. The analysis is performed using 310  pb−1 of s√=1.96  TeV pp collisions collected with the CDF II detector using a multijet trigger. The mass measurement is based on an event-by-event likelihood which depends on both the sample purity and the value of the top-quark mass, using 90 possible jet-to-parton assignments in the six-jet final state.

The joint likelihood of 290 selected events yields a value of Mtop=177.1±4.9(stat)±4.7(syst)   GeV/c2.

CDF Collaboration, CAMPANELLI, Mario (Collab.), et al . Measurement of the Top-Quark Mass in All-Hadronic Decays in pp Collisions at CDF II. Physical Review Letters , 2007, vol. 98, no.

14, p. 142001

DOI : 10.1103/PhysRevLett.98.142001

Available at:

http://archive-ouverte.unige.ch/unige:38408

Disclaimer: layout of this document may differ from the published version.

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Measurement of the Top-Quark Mass in All-Hadronic Decays in p p Collisions at CDF II

T. Aaltonen,²³A. Abulencia,²⁴J. Adelman,¹³T. Affolder,¹⁰T. Akimoto,⁵⁶M. G. Albrow,¹⁷D. Ambrose,¹⁷S. Amerio,⁴⁴ D. Amidei,³⁵A. Anastassov,⁵³K. Anikeev,¹⁷A. Annovi,¹⁹J. Antos,¹⁴M. Aoki,⁵⁶G. Apollinari,¹⁷J.-F. Arguin,³⁴ T. Arisawa,⁵⁸A. Artikov,¹⁵W. Ashmanskas,¹⁷A. Attal,⁸F. Azfar,⁴³P. Azzi-Bacchetta,⁴⁴P. Azzurri,⁴⁷N. Bacchetta,⁴⁴ W. Badgett,¹⁷A. Barbaro-Galtieri,²⁹V. E. Barnes,⁴⁹B. A. Barnett,²⁵S. Baroiant,⁷V. Bartsch,³¹G. Bauer,³³F. Bedeschi,⁴⁷

S. Behari,²⁵S. Belforte,⁵⁵G. Bellettini,⁴⁷J. Bellinger,⁶⁰A. Belloni,³³D. Benjamin,¹⁶A. Beretvas,¹⁷J. Beringer,²⁹ T. Berry,³⁰A. Bhatti,⁵¹M. Binkley,¹⁷D. Bisello,⁴⁴R. E. Blair,²C. Blocker,⁶B. Blumenfeld,²⁵A. Bocci,¹⁶A. Bodek,⁵⁰

V. Boisvert,⁵⁰G. Bolla,⁴⁹A. Bolshov,³³D. Bortoletto,⁴⁹J. Boudreau,⁴⁸A. Boveia,¹⁰B. Brau,¹⁰L. Brigliadori,⁵ C. Bromberg,³⁶E. Brubaker,¹³J. Budagov,¹⁵H. S. Budd,⁵⁰S. Budd,²⁴S. Budroni,⁴⁷K. Burkett,¹⁷G. Busetto,⁴⁴ P. Bussey,²¹K. L. Byrum,²S. Cabrera,^16,pM. Campanelli,²⁰M. Campbell,³⁵F. Canelli,¹⁷A. Canepa,⁴⁹S. Carillo,^18,j

D. Carlsmith,⁶⁰R. Carosi,⁴⁷M. Casarsa,⁵⁵A. Castro,⁵P. Catastini,⁴⁷D. Cauz,⁵⁵M. Cavalli-Sforza,³A. Cerri,²⁹ L. Cerrito,^43,nS. H. Chang,²⁸Y. C. Chen,¹M. Chertok,⁷G. Chiarelli,⁴⁷G. Chlachidze,¹⁵F. Chlebana,¹⁷I. Cho,²⁸K. Cho,²⁸ D. Chokheli,¹⁵J. P. Chou,²²G. Choudalakis,³³S. H. Chuang,⁶⁰K. Chung,¹²W. H. Chung,⁶⁰Y. S. Chung,⁵⁰M. Ciljak,⁴⁷

C. I. Ciobanu,²⁴M. A. Ciocci,⁴⁷A. Clark,²⁰D. Clark,⁶M. Coca,¹⁶G. Compostella,⁴⁴M. E. Convery,⁵¹J. Conway,⁷ B. Cooper,³⁶K. Copic,³⁵M. Cordelli,¹⁹G. Cortiana,⁴⁴F. Crescioli,⁴⁷C. Cuenca Almenar,⁷J. Cuevas,^11,mR. Culbertson,¹⁷

J. C. Cully,³⁵D. Cyr,⁶⁰S. DaRonco,⁴⁴M. Datta,¹⁷S. D’Auria,²¹T. Davies,²¹M. D’Onofrio,³D. Dagenhart,⁶ P. de Barbaro,⁵⁰S. De Cecco,⁵²A. Deisher,²⁹G. De Lentdecker,^50,dM. Dell’Orso,⁴⁷F. Delli Paoli,⁴⁴L. Demortier,⁵¹ J. Deng,¹⁶M. Deninno,⁵D. De Pedis,⁵²P. F. Derwent,¹⁷G. P. Di Giovanni,⁴⁵C. Dionisi,⁵²B. Di Ruzza,⁵⁵J. R. Dittmann,⁴ P. DiTuro,⁵³C. Do¨rr,²⁶S. Donati,⁴⁷M. Donega,²⁰P. Dong,⁸J. Donini,⁴⁴T. Dorigo,⁴⁴S. Dube,⁵³J. Efron,⁴⁰R. Erbacher,⁷

D. Errede,²⁴S. Errede,²⁴R. Eusebi,¹⁷H. C. Fang,²⁹S. Farrington,³⁰I. Fedorko,⁴⁷W. T. Fedorko,¹³R. G. Feild,⁶¹ M. Feindt,²⁶J. P. Fernandez,³²R. Field,¹⁸G. Flanagan,⁴⁹A. Foland,²²S. Forrester,⁷G. W. Foster,¹⁷M. Franklin,²² J. C. Freeman,²⁹I. Furic,¹³M. Gallinaro,⁵¹J. Galyardt,¹²J. E. Garcia,⁴⁷F. Garberson,¹⁰A. F. Garfinkel,⁴⁹C. Gay,⁶¹

H. Gerberich,²⁴D. Gerdes,³⁵S. Giagu,⁵²P. Giannetti,⁴⁷A. Gibson,²⁹K. Gibson,⁴⁸J. L. Gimmell,⁵⁰C. Ginsburg,¹⁷ N. Giokaris,^15,bM. Giordani,⁵⁵P. Giromini,¹⁹M. Giunta,⁴⁷G. Giurgiu,¹²V. Glagolev,¹⁵D. Glenzinski,¹⁷M. Gold,³⁸ N. Goldschmidt,¹⁸J. Goldstein,^43,cA. Golossanov,¹⁷G. Gomez,¹¹G. Gomez-Ceballos,¹¹M. Goncharov,⁵⁴O. Gonza´lez,³²

I. Gorelov,³⁸A. T. Goshaw,¹⁶K. Goulianos,⁵¹A. Gresele,⁴⁴M. Griffiths,³⁰S. Grinstein,²²C. Grosso-Pilcher,¹³ R. C. Group,¹⁸U. Grundler,²⁴J. Guimaraes da Costa,²²Z. Gunay-Unalan,³⁶C. Haber,²⁹K. Hahn,³³S. R. Hahn,¹⁷ E. Halkiadakis,⁵³A. Hamilton,³⁴B.-Y. Han,⁵⁰J. Y. Han,⁵⁰R. Handler,⁶⁰F. Happacher,¹⁹K. Hara,⁵⁶M. Hare,⁵⁷S. Harper,⁴³

R. F. Harr,⁵⁹R. M. Harris,¹⁷M. Hartz,⁴⁸K. Hatakeyama,⁵¹J. Hauser,⁸A. Heijboer,⁴⁶B. Heinemann,³⁰J. Heinrich,⁴⁶ C. Henderson,³³M. Herndon,⁶⁰J. Heuser,²⁶D. Hidas,¹⁶C. S. Hill,^10,cD. Hirschbuehl,²⁶A. Hocker,¹⁷A. Holloway,²² S. Hou,¹M. Houlden,³⁰S.-C. Hsu,⁹B. T. Huffman,⁴³R. E. Hughes,⁴⁰U. Husemann,⁶¹J. Huston,³⁶J. Incandela,¹⁰

G. Introzzi,⁴⁷M. Iori,⁵²Y. Ishizawa,⁵⁶A. Ivanov,⁷B. Iyutin,³³E. James,¹⁷D. Jang,⁵³B. Jayatilaka,³⁵D. Jeans,⁵² H. Jensen,¹⁷E. J. Jeon,²⁸S. Jindariani,¹⁸M. Jones,⁴⁹K. K. Joo,²⁸S. Y. Jun,¹²J. E. Jung,²⁸T. R. Junk,²⁴T. Kamon,⁵⁴

P. E. Karchin,⁵⁹Y. Kato,⁴²Y. Kemp,²⁶R. Kephart,¹⁷U. Kerzel,²⁶V. Khotilovich,⁵⁴B. Kilminster,⁴⁰D. H. Kim,²⁸ H. S. Kim,²⁸J. E. Kim,²⁸M. J. Kim,¹²S. B. Kim,²⁸S. H. Kim,⁵⁶Y. K. Kim,¹³N. Kimura,⁵⁶L. Kirsch,⁶S. Klimenko,¹⁸

M. Klute,³³B. Knuteson,³³B. R. Ko,¹⁶K. Kondo,⁵⁸D. J. Kong,²⁸J. Konigsberg,¹⁸A. Korytov,¹⁸A. V. Kotwal,¹⁶ A. Kovalev,⁴⁶A. C. Kraan,⁴⁶J. Kraus,²⁴I. Kravchenko,³³M. Kreps,²⁶J. Kroll,⁴⁶N. Krumnack,⁴M. Kruse,¹⁶ V. Krutelyov,¹⁰T. Kubo,⁵⁶S. E. Kuhlmann,²T. Kuhr,²⁶Y. Kusakabe,⁵⁸S. Kwang,¹³A. T. Laasanen,⁴⁹S. Lai,³⁴S. Lami,⁴⁷ S. Lammel,¹⁷M. Lancaster,³¹R. L. Lander,⁷K. Lannon,⁴⁰A. Lath,⁵³G. Latino,⁴⁷I. Lazzizzera,⁴⁴T. LeCompte,²J. Lee,⁵⁰ J. Lee,²⁸Y. J. Lee,²⁸S. W. Lee,^54,oR. Lefe`vre,³N. Leonardo,³³S. Leone,⁴⁷S. Levy,¹³J. D. Lewis,¹⁷C. Lin,⁶¹C. S. Lin,¹⁷

M. Lindgren,¹⁷E. Lipeles,⁹A. Lister,⁷D. O. Litvintsev,¹⁷T. Liu,¹⁷N. S. Lockyer,⁴⁶A. Loginov,⁶¹M. Loreti,⁴⁴ P. Loverre,⁵²R.-S. Lu,¹D. Lucchesi,⁴⁴P. Lujan,²⁹P. Lukens,¹⁷G. Lungu,¹⁸L. Lyons,⁴³J. Lys,²⁹R. Lysak,¹⁴E. Lytken,⁴⁹

P. Mack,²⁶D. MacQueen,³⁴R. Madrak,¹⁷K. Maeshima,¹⁷K. Makhoul,³³T. Maki,²³P. Maksimovic,²⁵S. Malde,⁴³ G. Manca,³⁰F. Margaroli,⁵R. Marginean,¹⁷C. Marino,²⁶C. P. Marino,²⁴A. Martin,⁶¹M. Martin,²¹V. Martin,^21,h M. Martı´nez,³T. Maruyama,⁵⁶P. Mastrandrea,⁵²T. Masubuchi,⁵⁶H. Matsunaga,⁵⁶M. E. Mattson,⁵⁹R. Mazini,³⁴

P. Mazzanti,⁵K. S. McFarland,⁵⁰P. McIntyre,⁵⁴R. McNulty,^30,gA. Mehta,³⁰P. Mehtala,²³S. Menzemer,^11,i A. Menzione,⁴⁷P. Merkel,⁴⁹C. Mesropian,⁵¹A. Messina,³⁶T. Miao,¹⁷N. Miladinovic,⁶J. Miles,³³R. Miller,³⁶C. Mills,¹⁰ M. Milnik,²⁶A. Mitra,¹G. Mitselmakher,¹⁸A. Miyamoto,²⁷S. Moed,²⁰N. Moggi,⁵B. Mohr,⁸R. Moore,¹⁷M. Morello,⁴⁷ P. Movilla Fernandez,²⁹J. Mu¨lmensta¨dt,²⁹A. Mukherjee,¹⁷Th. Muller,²⁶R. Mumford,²⁵P. Murat,¹⁷J. Nachtman,¹⁷

A. Nagano, J. Naganoma, I. Nakano, A. Napier, V. Necula, C. Neu, M. S. Neubauer, J. Nielsen, T. Nigmanov,⁴⁸L. Nodulman,²O. Norniella,³E. Nurse,³¹S. H. Oh,¹⁶Y. D. Oh,²⁸I. Oksuzian,¹⁸T. Okusawa,⁴² R. Oldeman,³⁰R. Orava,²³K. Osterberg,²³C. Pagliarone,⁴⁷E. Palencia,¹¹V. Papadimitriou,¹⁷A. A. Paramonov,¹³ B. Parks,⁴⁰S. Pashapour,³⁴J. Patrick,¹⁷G. Pauletta,⁵⁵M. Paulini,¹²C. Paus,³³D. E. Pellett,⁷A. Penzo,⁵⁵T. J. Phillips,¹⁶

G. Piacentino,⁴⁷J. Piedra,⁴⁵L. Pinera,¹⁸K. Pitts,²⁴C. Plager,⁸L. Pondrom,⁶⁰X. Portell,³O. Poukhov,¹⁵N. Pounder,⁴³ F. Prakoshyn,¹⁵A. Pronko,¹⁷J. Proudfoot,²F. Ptohos,^19,fG. Punzi,⁴⁷J. Pursley,²⁵J. Rademacker,^43,cA. Rahaman,⁴⁸

N. Ranjan,⁴⁹S. Rappoccio,²²B. Reisert,¹⁷V. Rekovic,³⁸P. Renton,⁴³M. Rescigno,⁵²S. Richter,²⁶F. Rimondi,⁵ L. Ristori,⁴⁷A. Robson,²¹T. Rodrigo,¹¹E. Rogers,²⁴S. Rolli,⁵⁷R. Roser,¹⁷M. Rossi,⁵⁵R. Rossin,¹⁸A. Ruiz,¹¹J. Russ,¹²

V. Rusu,¹³H. Saarikko,²³S. Sabik,³⁴A. Safonov,⁵⁴W. K. Sakumoto,⁵⁰G. Salamanna,⁵²O. Salto´,³D. Saltzberg,⁸ C. Sa´nchez,³L. Santi,⁵⁵S. Sarkar,⁵²L. Sartori,⁴⁷K. Sato,¹⁷P. Savard,³⁴A. Savoy-Navarro,⁴⁵T. Scheidle,²⁶P. Schlabach,¹⁷

E. E. Schmidt,¹⁷M. P. Schmidt,⁶¹M. Schmitt,³⁹T. Schwarz,⁷L. Scodellaro,¹¹A. L. Scott,¹⁰A. Scribano,⁴⁷F. Scuri,⁴⁷ A. Sedov,⁴⁹S. Seidel,³⁸Y. Seiya,⁴²A. Semenov,¹⁵L. Sexton-Kennedy,¹⁷A. Sfyrla,²⁰M. D. Shapiro,²⁹T. Shears,³⁰

P. F. Shepard,⁴⁸D. Sherman,²²M. Shimojima,^56,lM. Shochet,¹³Y. Shon,⁶⁰I. Shreyber,³⁷A. Sidoti,⁴⁷P. Sinervo,³⁴ A. Sisakyan,¹⁵J. Sjolin,⁴³A. J. Slaughter,¹⁷J. Slaunwhite,⁴⁰K. Sliwa,⁵⁷J. R. Smith,⁷F. D. Snider,¹⁷R. Snihur,³⁴ M. Soderberg,³⁵A. Soha,⁷S. Somalwar,⁵³V. Sorin,³⁶J. Spalding,¹⁷F. Spinella,⁴⁷T. Spreitzer,³⁴P. Squillacioti,⁴⁷ M. Stanitzki,⁶¹A. Staveris-Polykalas,⁴⁷R. St. Denis,²¹B. Stelzer,⁸O. Stelzer-Chilton,⁴³D. Stentz,³⁹J. Strologas,³⁸ D. Stuart,¹⁰J. S. Suh,²⁸A. Sukhanov,¹⁸H. Sun,⁵⁷T. Suzuki,⁵⁶A. Taffard,²⁴R. Takashima,⁴¹Y. Takeuchi,⁵⁶K. Takikawa,⁵⁶

M. Tanaka,²R. Tanaka,⁴¹M. Tecchio,³⁵P. K. Teng,¹K. Terashi,⁵¹J. Thom,^17,eA. S. Thompson,²¹E. Thomson,⁴⁶ P. Tipton,⁶¹V. Tiwari,¹²S. Tkaczyk,¹⁷D. Toback,⁵⁴S. Tokar,¹⁴K. Tollefson,³⁶T. Tomura,⁵⁶D. Tonelli,⁴⁷S. Torre,¹⁹

D. Torretta,¹⁷S. Tourneur,⁴⁵W. Trischuk,³⁴R. Tsuchiya,⁵⁸S. Tsuno,⁴¹N. Turini,⁴⁷F. Ukegawa,⁵⁶T. Unverhau,²¹ S. Uozumi,⁵⁶D. Usynin,⁴⁶S. Vallecorsa,²⁰N. van Remortel,²³A. Varganov,³⁵E. Vataga,³⁸F. Va´zquez,^18,jG. Velev,¹⁷ G. Veramendi,²⁴V. Veszpremi,⁴⁹R. Vidal,¹⁷I. Vila,¹¹R. Vilar,¹¹T. Vine,³¹I. Vollrath,³⁴I. Volobouev,^29,oG. Volpi,⁴⁷

F. Wu¨rthwein,⁹P. Wagner,⁵⁴R. G. Wagner,²R. L. Wagner,¹⁷J. Wagner,²⁶W. Wagner,²⁶R. Wallny,⁸S. M. Wang,¹ A. Warburton,³⁴S. Waschke,²¹D. Waters,³¹W. C. Wester III,¹⁷B. Whitehouse,⁵⁷D. Whiteson,⁴⁶A. B. Wicklund,² E. Wicklund,¹⁷G. Williams,³⁴H. H. Williams,⁴⁶P. Wilson,¹⁷B. L. Winer,⁴⁰P. Wittich,^17,eS. Wolbers,¹⁷C. Wolfe,¹³

T. Wright,³⁵X. Wu,²⁰S. M. Wynne,³⁰A. Yagil,¹⁷K. Yamamoto,⁴²J. Yamaoka,⁵³T. Yamashita,⁴¹C. Yang,⁶¹ U. K. Yang,^13,kY. C. Yang,²⁸W. M. Yao,²⁹G. P. Yeh,¹⁷J. Yoh,¹⁷K. Yorita,¹³T. Yoshida,⁴²G. B. Yu,⁵⁰I. Yu,²⁸S. S. Yu,¹⁷

J. C. Yun,¹⁷L. Zanello,⁵²A. Zanetti,⁵⁵I. Zaw,²²X. Zhang,²⁴J. Zhou,⁵³and S. Zucchelli⁵ (CDF Collaboration)^a

1Institute of Physics, Academia Sinica, Taipei, Taiwan 11529, Republic of China

2Argonne National Laboratory, Argonne, Illinois 60439, USA

3Institut de Fisica d’Altes Energies, Universitat Autonoma de Barcelona, E-08193, Bellaterra (Barcelona), Spain

4Baylor University, Waco, Texas 76798, USA

5Istituto Nazionale di Fisica Nucleare, University of Bologna, I-40127 Bologna, Italy

6Brandeis University, Waltham, Massachusetts 02254, USA

7University of California, Davis, Davis, California 95616, USA

8University of California, Los Angeles, Los Angeles, California 90024, USA

9University of California, San Diego, La Jolla, California 92093, USA

10University of California, Santa Barbara, Santa Barbara, California 93106, USA

11Instituto de Fisica de Cantabria, CSIC-University of Cantabria, 39005 Santander, Spain

12Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA

13Enrico Fermi Institute, University of Chicago, Chicago, Illinois 60637, USA

14Comenius University, 842 48 Bratislava, Slovakia; Institute of Experimental Physics, 040 01 Kosice, Slovakia

15Joint Institute for Nuclear Research, RU-141980 Dubna, Russia

16Duke University, Durham, North Carolina 27708

17Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA

18University of Florida, Gainesville, Florida 32611, USA

19Laboratori Nazionali di Frascati, Istituto Nazionale di Fisica Nucleare, I-00044 Frascati, Italy

20University of Geneva, CH-1211 Geneva 4, Switzerland

21Glasgow University, Glasgow G12 8QQ, United Kingdom

22Harvard University, Cambridge, Massachusetts 02138, USA

23Division of High Energy Physics, Department of Physics, University of Helsinki and Helsinki Institute of Physics, FIN-00014, Helsinki, Finland

142001-2

24University of Illinois, Urbana, Illinois 61801, USA

25The Johns Hopkins University, Baltimore, Maryland 21218, USA

26Institut fu¨r Experimentelle Kernphysik, Universita¨t Karlsruhe, 76128 Karlsruhe, Germany

27High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305, Japan

28Center for High Energy Physics: Kyungpook National University, Taegu 702-701, Korea;

Seoul National University, Seoul 151-742, Korea;

and SungKyunKwan University, Suwon 440-746, Korea

29Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA

30University of Liverpool, Liverpool L69 7ZE, United Kingdom

31University College London, London WC1E 6BT, United Kingdom

32Centro de Investigaciones Energeticas Medioambientales y Tecnologicas, E-28040 Madrid, Spain

33Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA

34Institute of Particle Physics: McGill University, Montre´al, Canada H3A 2T8;

and University of Toronto, Toronto, Canada M5S 1A7

35University of Michigan, Ann Arbor, Michigan 48109, USA

36Michigan State University, East Lansing, Michigan 48824, USA

37Institution for Theoretical and Experimental Physics, ITEP, Moscow 117259, Russia

38University of New Mexico, Albuquerque, New Mexico 87131, USA

39Northwestern University, Evanston, Illinois 60208, USA

40The Ohio State University, Columbus, Ohio 43210, USA

41Okayama University, Okayama 700-8530, Japan

42Osaka City University, Osaka 588, Japan

43University of Oxford, Oxford OX1 3RH, United Kingdom

44University of Padova, Istituto Nazionale di Fisica Nucleare, Sezione di Padova-Trento, I-35131 Padova, Italy

45LPNHE, Universite Pierre et Marie Curie/IN2P3-CNRS, UMR7585, Paris, F-75252 France

46University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA

47Istituto Nazionale di Fisica Nucleare Pisa, Universities of Pisa, Siena and Scuola Normale Superiore, I-56127 Pisa, Italy

48University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA

49Purdue University, West Lafayette, Indiana 47907, USA

50University of Rochester, Rochester, New York 14627, USA

51The Rockefeller University, New York, New York 10021, USA

52Istituto Nazionale di Fisica Nucleare, Sezione di Roma 1, University of Rome ‘‘La Sapienza,’’ I-00185 Roma, Italy

53Rutgers University, Piscataway, New Jersey 08855, USA

54Texas A&M University, College Station, Texas 77843, USA

55Istituto Nazionale di Fisica Nucleare, University of Trieste/ Udine, Italy

56University of Tsukuba, Tsukuba, Ibaraki 305, Japan

57Tufts University, Medford, Massachusetts 02155, USA

58Waseda University, Tokyo 169, Japan

59Wayne State University, Detroit, Michigan 48201, USA

60University of Wisconsin, Madison, Wisconsin 53706, USA

61Yale University, New Haven, Connecticut 06520, USA (Received 12 December 2006; published 3 April 2007)

We present a measurement of the top-quark mass M_top in the all-hadronic decay channel tt! WbWb!q₁q₂bq₃q₄b. The analysis is performed using 310 pb¹ of

ps

1:96 TeVpp collisions collected with the CDF II detector using a multijet trigger. The mass measurement is based on an event- by-event likelihood which depends on both the sample purity and the value of the top-quark mass, using 90 possible jet-to-parton assignments in the six-jet final state. The joint likelihood of 290 selected events yields a value ofMtop177:14:9stat 4:7systGeV=c².

DOI:10.1103/PhysRevLett.98.142001 PACS numbers: 14.65.Ha, 12.15.Ff

The mass of the top quark, M_top, is an important free parameter of the standard model (SM) and is of the order of the electroweak symmetry breaking scale. Since virtual top quarks are involved in higher-order electroweak processes, by measuring the top-quark mass, one can constrain the mass of the SM Higgs boson [1] and particles predicted in extensions of the SM [2]. At the Tevatron, tt pairs are produced by QCD processes and decay according to the

CKM matrix [3] with a branching ratio of almost 100%

into aWboson and abquark. The final state of the event is then defined by the decay of theW bosons. All-hadronictt events, where both of theWbosons decay into quarks, have a multijet final state and no missing energy due to neutri- nos. The top-quark mass measurement in this decay chan- nel is motivated by the large branching fraction (44%) and the complete reconstruction of both top and antitop

quarks, relying only on hadronic jets. It is the first top- quark mass measurement in this channel using Tevatron Run II data, and serves as a consistency check of the measurements in the two other tt decay modes [4–6].

The major experimental challenge is the presence of a large amount of multijet background events from QCD processes, which dominatesttproduction by 3 orders of magnitude, even after applying a trigger dedicated to events with a multijet final state.

In this Letter, we present the measurement of the top- quark mass in the all-hadronic decay channel using a sample of tt decays corresponding to 310 pb¹ of proton-antiproton collisions at ps

1:96 TeV, collected using the Collider Detector at Fermilab II (CDF II) detector between February 2002, and August 2004. We measure the mass using the ideogram method, which was used in the DELPHI experiment at LEP for theW boson mass mea- surement [7]. The method is based on an event-by-event likelihood that reconstructs the top and antitop quarks using all 90 assignments of jets to quarks fromW boson decays andbquarks (jet combinations) from thettdecay.

Considering all jet combinations enhances the amount of top-quark mass information we can extract from each event.

The sample purity, P, defined as the fraction of all- hadronic ttevents contained in the selected data sample, is a free parameter of the likelihood together with the value ofM_top. The reason for measuring bothM_topandP simul- taneously is that the cross sections of the QCD back- grounds are not well known. Even though the back- ground processes do not contain any top-quark mass infor- mation, the sensitivity of the likelihood on M_top does depend on the total amount of QCD background events.

This is reflected both in the statistical variance ofM_topand in corrections applied toM_topwhich take into account the presence of background events.

The CDF II detector [8] is a general-purpose charged and neutral particle detector designed to study pp colli- sions at the Fermilab Tevatron. It consists of an eight-layer silicon microstrip detector array and a cylindrical drift chamber contained inside a 1.4-T solenoid magnet, sur- rounded by electromagnetic and hadronic sampling calo- rimeters with a geometrical acceptance up to a pseudo- rapidity ofjj 3:6[9]. Muon chambers are located out- side the calorimeters, allowing the reconstruction of track segments for penetrating particles.

The data set used for this measurement is selected with a multijet trigger that relies solely on calorimetry. This trig- ger requires at least four calorimeter clusters with a trans- verse energy E_T >15 GeV and the scalar sum of the transverse jet energies to exceed 125 GeV. To improve the signal-to-background ratio, we impose offline kine- matic requirements based on the scalar sum of the trans- verse jet energies and event shape observables. A full description of the trigger and kinematic selection is given

in an earlier publication [10]. For the final top-quark mass measurement, we consider only events with exactly six jets, each with transverse energyE_T>15 GeVand pseu- dorapidityjj 2. Jets are identified as clusters of energy deposits in the calorimeter segments (towers) which fall

within a cone radius of R

²²

p 0:4 [9].

The jet energies are calibrated, based on both instrumental calibration and analysis of data control samples [11]. We apply additional jet-parton energy corrections, specific tott events, which are parameterized independently forb-quark jets and light-flavor jets [12].

In order to further reduce the QCD background, we apply b-quark identification to each event passing the kinematic selection. At least one jet must have a recon- structed displaced vertex (b-tag), consistent with a long- lived bottom hadron [13]. This displaced vertex informa- tion is not used to reduce the number of jet combinations in the event likelihood. Instead, we derive a weight factor using the CDF jet probability algorithm [14] which takes into account the probability that a jet originates from ab quark, as explained below. The final data sample contains 290 events. Assuming a theoretical cross section of 6.1 pb [15] for a top-quark mass of 178 GeV=c² [16], the ex- pected signal-to-background ratio is about one-to-five.

By applying energy and momentum conservation, we fit the momenta of the jets and the two top-quark masses, m^1;2_i , and determine their estimated uncertainties,^1;2_i us- ing a²minimization. This kinematic fit is applied to each of the 90 jet combinations, i, where we constrain the masses of the two W bosons to a world average value of m_W 80:4 GeV=c² [3] within their natural widths. In order to achieve a better background reduction, the two reconstructed top-quark masses,m^1;2_i , are not constrained to be equal. We measure M_top using an event likelihood where we weigh each combination i with a factor w_i, expressing the compatibility with both the ttdecay kine- matics and the presence of twob-quark jets together with four light-flavor jets. The weight factorw_iis calculated as

w_iexp

1 2²_i Y²

j1

p^b_jY⁶

j3

p^q_j; (1) where the exponential term, calculated using the ²value of the kinematic fit, is a measure of the compatibility of jet combination i with the kinematics of a decaying ttpair.

The second factor gives the probability of two of the jets to originate from ab(orb) quark and four others to originate from light quarks (including cquarks), where we assume quarks with indices 3– 6 to be light quarks originating from the W bosons. The probabilityp^bor_j ^q for a jetjto origi- nate from a bquark (or light-flavor quark,q) is obtained using the CDF jet probability algorithm [14]. This calcu- lates the probabilityP_jfor a given jetjto originate from the primary vertex, based on the impact parameter infor- mation from the tracks belonging to that jet. The P_j dis- 142001-4

tribution forb-quark jets (or light-flavor jets) is described by a probability density function,fborqjP_jin order to obtain

p^bor_j ^q fborqjP_j

fbjP_j fqjP_j: (2) The event likelihood consists of two terms. The si- gnal likelihood term corresponds to the convolution of two Breit-Wigner distributions, F_BWm⁰_jjM_top, with two Gaussians, Gm⁰_jjm^j_i; ^j_i, describing the experimental resolutions, ^1;2_i , for each of the two reconstructed top- quark masses,m^1;2_i :

L^sig_i M_top Y

j1;2

Z Gm⁰_jjm^j_i; ^j_iF_BWm⁰_jjM_topdm⁰_j:

(3) The M_top-independent background likelihood term, L^bg_i , corresponds to the two-dimensional posteriori probability density function (histogram) ofm^1;2_i obtained fromALPGEN

[17] Monte Carlo (MC) multijet QCD background. All MC events are passed through the CDF detector simulation and are subjected to the same event selection criteria as the data.

The likelihood for a given event nis derived by sum- ming the signal and background event likelihoods for each jet combinationiand is calculated as a function of the top- quark mass,M_top, and the sample purity,P:

LⁿM_top;P X⁹⁰

i1

w_iP L^sig_i M_top 1PL^bg_i : (4) We obtain a one-dimensional likelihood curve as a function ofM_topby maximizing the two-dimensional joint likelihood with respect to the sample purity,P, for each value ofM_top. The maximum of the total likelihood of the 290 selected data events corresponds to a sample purity value ofP 0:210:07stat, which is compatible with a signal-to-background ratio of about one-to-five expected from SMttproduction.

The value ofM_topextracted from the joint likelihood fit is biased due to the presence of wrong jet combinations, background events, and assignment of jets that arise from initial- (ISR) and final-state gluon radiation (FSR).

Therefore, we correct the measurement of M_top using a linear parameterization of the correlation between the gen- erated top-quark mass value and the mass estimatorM_topin the range between 160 GeV=c² and 190 GeV=c², as shown in Fig. 1. Each mass point is obtained from pseu- doexperiments with MC samples containing a mixture of 290 Poisson-fluctuated signal plus background events. We use HERWIG [18] to generate the tt signal events and

ALPGENto model the QCD background. The tag rate matrix used in [10] models the false identification of b-quarks.

The correction depends on the sample purity used to con- struct the pseudoexperiments as illustrated by the shaded band which corresponds to the one-sigma statistical uncer- tainty on the sample purity measured from data.

Accordingly, we assign a systematic uncertainty due to this purity uncertainty. Using the same pseudoexperiments, we verify that the measured sample purity is independent of the generator top-quark mass value and that the statis- tical uncertainty on M_top covers 68% of the sample mea- surements. We correct the statistical uncertainty from the likelihood curve using the width of the pull distribution M_topm_gen=_Mtop, where m_gen is the generated top- quark mass,M_topthe measured top-quark mass, and_Mtop its statistical uncertainty obtained in the pseudoexperi- ments. The correction factor, 1.17, is independent of the value ofM_top.

The maximum of the one-dimensional top mass like- lihood, after correction with the parameterization shown in Fig. 1, corresponds to the value M_top177:1 4:9stat GeV=c². Figure 2 shows the corresponding likelihood.

The uncertainty on the jet energy scale (JES) which varies between approximately 3% and 8% of the measured jet energy, depending on the and p_T of the jet [11], dominates the systematic uncertainties on our measure- ment ofM_top. We determine its effect using pseudoexperi- ments in which the JES is increased (decreased) with 1 standard deviation. We symmetrize the uncertainty by taking half of the difference in M_top between the positive and negative variation of the JES, resulting in M_top 4:3 GeV=c². The corrections to M_top, shown in Fig. 1, depend both on the background fraction and shape. The

2] Generated mass - 175 [GeV/c

-15 -10 -5 0 5 10 15

]2Fitted mass - 175 [GeV/c

-15 -10 -5 0 5 10

15 pseudo-experiments linear parameterization background fraction uncertainty unbiased measurement

FIG. 1 (color online). The correlation between the measured value of M_top and the generated top-quark mass obtained with pseudoexperiments usingttsignal events generated withHERWIG

and an admixture of QCD background generated with ALPGEN. The solid line represents the linear parameterization used to correct M_top. The shaded band shows the effect of a one-sigma variation of the sample purity, P 0:210:07stat. The dashed line corresponds to 100% correlation and zero offset.

uncertainty due to the background fraction, varied within the uncertainties of the measured sample purity, is M_top 1:1 GeV=c² for the measured value of M_top. The relative fractions of the light-flavor QCD background and QCD background containingbquarks is not precisely known. We estimate their ratio (light-flavor/b) to be 2.8 1:0by performing a binned maximum likelihood fit of the MC expectation to the data based on the jet probability weight distribution in Eq. (1). This result is consistent with a value of 2.7 obtained using the respective QCD cross sections given by theALPGENevent generator, taking the individual selection efficiencies into account. A systematic uncertainty due to the background composition results in M_top 0:8 GeV=c² by varying the background flavor composition between only light-flavor QCD background events and only QCD background containingbquarks. In accordance with [5], we vary two PYTHIA [19] parton shower parameters, _QCD, and the ISR/FSR transverse momentum scale K-factor, in order to model the system- atic uncertainties due to the amount of ISR and FSR. The largest difference observed inM_top between any variation amounts to0:9 GeV=c² (0:8 GeV=c²) for ISR (FSR). To examine the systematic effect due to uncertainties in the parton distribution function (PDF) of the proton, we follow the approach used in [5], resulting inM_top0:8 GeV=c². By applying the parameterized corrections on M_top ob- tained withHERWIG to MC events generated withPYTHIA, we estimate MC modeling uncertainties. The resulting difference in M_top equals 0:5 GeV=c². Uncertainties in b-quark fragmentation, semileptonic branching ratios, and color flow affect the b-quark JES [5]. This results in an additional contribution to M_top of 0:5 GeV=c². All systematic uncertainties are summarized in TableI. They result in a total systematic uncertainty of M_top 4:7 GeV=c².

In summary, we present a new measurement of the top- quark mass in the all-hadronic channel. The measured

value is M_top 177:14:9stat 4:7syst GeV=c². This measurement is the first determination of the top- quark mass in the all-hadronic channel using Run II data and is twice as precise as the Run I measurements in this channel [20,21]. Our result can be compared with the latest CDF top-quark mass measurements in the dilepton [4] and lepton+jets [5] channel, which are based on samples with a similar integrated luminosity. At the current level of pre- cision, the values ofM_topare compatible between all three decay channels.

We 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 Foun- dation; the A.P. Sloan Foundation; the Bundesminis- terium fu¨r Bildung und Forschung, Germany; the Korean Science and Engineering Foundation and the Korean Research Foundation; the Particle Physics and Astronomy Research Council and the Royal Society, UK;

the Institut National de Physique Nucleaire et Physique des Particules/CNRS; the Russian Foundation for Basic Research; the Comisio´n Interministerial de Ciencia y Tecnologı´a, Spain; the European Community’s Human Potential Programme under contract No. HPRN-CT- 2002-00292; and the Academy of Finland.

aWith visitors from

bUniversity of Athens

cUniversity of Bristol

dUniversity Libre de Bruxelles

eCornell University

fUniversity of Cyprus

gUniversity of Dublin

hUniversity of Edinburgh mass.

Systematic uncertainty source M_top[GeV=c²]

JES 4.3

Background fraction 1.1

Background shape 0.8

ISR 0.9

FSR 0.8

PDF 0.8

MC modeling (generator) 0.5

b-quark JES 0.5

Total 4.7

2] [GeV/c Mtop

170 172 174 176 178 180 182 184

log L∆

0 0.2 0.4 0.6 0.8 1

FIG. 2. The one-dimensional negative log-likelihood ofM_top obtained including corrections using the parameterization shown in Fig.1.

142001-6

iUniversity of Heidelberg

jUniversidad Iberoamericana

kUniversity of Manchester

lNagasaki Institute of Applied Science

mUniversity de Oviedo

nUniversity of London, Queen Mary and Westfield College

oTX Tech University, USA

pIFIC(CSIC-Universitat de Valencia)

[1] The LEP Collaborations, LEP Electroweak Working Group, and SLD Electroweak and Heavy Flavor Groups, CERN, Report No. CERN-PH-EP/2005-051, 2005 (unpublished).

[2] S. Heinemeyeret al., J. High Energy Phys. 09 (2003) 075.

[3] W-M. Yao et al., J. Phys. G Nucl. Part. Phys. 33, 1 (2006).

[4] A. Abulenciaet al.(CDF Collaboration), Phys. Rev. Lett.

96, 152002 (2006); A. Abulencia et al. (CDF Collabo- ration), Phys. Rev. D74, 032009 (2006).

[5] A. Abulenciaet al.(CDF Collaboration), Phys. Rev. Lett.

96, 022004 (2006); A. Abulencia et al. (CDF Collabo- ration), Phys. Rev. D73, 032003 (2006).

[6] V. M. Abazovet al.(D0 Collaboration), Phys. Rev. D74, 092005 (2006).

[7] P. Abreuet al.(DELPHI Collaboration), Eur. Phys. J. C2, 581 (1998).

[8] D. Acosta et al. (CDF Collaboration), Phys. Rev. D 71, 032001 (2005).

[9] The CDF reference frame uses cylindrical coordinates, whereand are the polar and azimuthal angles with

respect to the proton beam. The pseudorapidity is defined as lntan=2, the transverse energy asE_TEsin, and transverse momentum asp_Tpsin.

[10] A. Abulenciaet al.(CDF Collaboration), Phys. Rev. D74, 072005 (2006).

[11] A. Bhattiet al., Nucl. Instrum. Methods Phys. Res., Sect.

A566, 375 (2006).

[12] The term light-flavor is used for up, down, strange, and charm flavored quarks or combinations of these.

[13] D. Acosta et al.(CDF Collaboration), Phys. Rev. D71, 052003 (2005).

[14] A. Abulenciaet al.(CDF Collaboration), Phys. Rev. D74, 072006 (2006).

[15] M. Cacciari et al., J. High Energy Phys. 04 (2004) 068;

N. Kidonakis and R. Vogt, Phys. Rev. D 68, 114014 (2003).

[16] P. Azziet al.(CDF Collaboration), hep-ex/0404010.

[17] M. L. Mangano, M. Moretti, F. Piccinini, R. Pittau, and A. Polosa, J. High Energy Phys. 07 (2003) 001; M. L.

Mangano, M. Moretti, and R. Pittau, Nucl. Phys. B632, 343 (2002); F. Caravaglios, M. L. Mangano, M. Moretti, and R. Pittau, Nucl. Phys.B539, 215 (1999).

[18] G. Corcellaet al., J. High Energy Phys. 01 (2001) 010.

[19] T. Sjostrand, S. Mrenna, and P. Skands, J. High Energy Phys. 05 (2006) 026.

[20] T. Affolderet al.(CDF Collaboration), Phys. Rev. D63, 032003 (2001).

[21] V. M. Abazovet al.(D0 Collaboration), Phys. Lett. B606, 25 (2005).