Polarizations of <em>J/ψ</em> and <em>ψ</em>(2S) Mesons Produced in <em>pp</em> Collisions at s√=1.96  TeV

Article

Reference

Polarizations of J/ψ and ψ (2S) Mesons Produced in pp Collisions at s√=1.96  TeV

CDF Collaboration

CAMPANELLI, Mario (Collab.), et al.

Abstract

We have measured the polarizations of J/ψ and ψ(2S) mesons as functions of their transverse momentum pT when they are produced promptly in the rapidity range |y|

CDF Collaboration, CAMPANELLI, Mario (Collab.), et al . Polarizations of J/ψ and ψ (2S) Mesons Produced in pp Collisions at s√=1.96  TeV. Physical Review Letters , 2007, vol. 99, no. 13, p.

132001

DOI : 10.1103/PhysRevLett.99.132001

Available at:

http://archive-ouverte.unige.ch/unige:38400

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

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Polarizations of J= and 2S Mesons Produced in p p Collisions at p s

1:96 TeV

A. Abulencia,²⁴J. Adelman,¹³T. Affolder,¹⁰T. Akimoto,⁵⁵M. G. Albrow,¹⁷S. Amerio,⁴³D. Amidei,³⁵A. Anastassov,⁵² K. Anikeev,¹⁷A. Annovi,¹⁹J. Antos,¹⁴M. Aoki,⁵⁵G. Apollinari,¹⁷T. Arisawa,⁵⁷A. Artikov,¹⁵W. Ashmanskas,¹⁷

A. Attal,¹³A. Aurisano,⁴²F. Azfar,⁴²P. Azzi-Bacchetta,⁴³P. Azzurri,⁴⁶N. Bacchetta,⁴³W. Badgett,¹⁷ A. Barbaro-Galtieri,²⁹V. E. Barnes,⁴⁸B. A. Barnett,²⁵S. Baroiant,⁷V. Bartsch,³¹G. Bauer,³³P.-H. Beauchemin,³⁴ F. Bedeschi,⁴⁶S. Behari,²⁵G. Bellettini,⁴⁶J. Bellinger,⁵⁹A. Belloni,³³D. Benjamin,¹⁶A. Beretvas,¹⁷J. Beringer,²⁹ T. Berry,³⁰A. Bhatti,⁵⁰M. Binkley,¹⁷D. Bisello,⁴³I. Bizjak,³¹R. E. Blair,²C. Blocker,⁶B. Blumenfeld,²⁵A. Bocci,¹⁶

A. Bodek,⁴⁹V. Boisvert,⁴⁹G. Bolla,⁴⁸A. Bolshov,³³D. Bortoletto,⁴⁸J. Boudreau,⁴⁷A. Boveia,¹⁰B. Brau,¹⁰ L. Brigliadori,⁵C. Bromberg,³⁶E. Brubaker,¹³J. Budagov,¹⁵H. S. Budd,⁴⁹S. Budd,²⁴K. Burkett,¹⁷G. Busetto,⁴³ P. Bussey,²¹A. Buzatu,³⁴K. L. Byrum,²S. Cabrera,^16,qM. Campanelli,²⁰M. Campbell,³⁵F. Canelli,¹⁷A. Canepa,⁴⁵ S. Carillo,^18,iD. Carlsmith,⁵⁹R. Carosi,⁴⁶S. Carron,³⁴B. Casal,¹¹M. Casarsa,⁵⁴A. Castro,⁵P. Catastini,⁴⁶D. Cauz,⁵⁴ M. Cavalli-Sforza,³A. Cerri,²⁹L. Cerrito,^31,mS. H. Chang,²⁸Y. C. Chen,¹M. Chertok,⁷G. Chiarelli,⁴⁶G. Chlachidze,¹⁷

F. Chlebana,¹⁷I. Cho,²⁸K. Cho,²⁸D. Chokheli,¹⁵J. P. Chou,²²G. Choudalakis,³³S. H. Chuang,⁵²K. Chung,¹² W. H. Chung,⁵⁹Y. S. Chung,⁴⁹M. Cilijak,⁴⁶C. I. Ciobanu,²⁴M. A. Ciocci,⁴⁶A. Clark,²⁰D. Clark,⁶M. Coca,¹⁶ G. Compostella,⁴³M. E. Convery,⁵⁰J. Conway,⁷B. Cooper,³¹K. Copic,³⁵M. Cordelli,¹⁹G. Cortiana,⁴³F. Crescioli,⁴⁶ C. Cuenca Almenar,^7,qJ. Cuevas,^11,lR. Culbertson,¹⁷J. C. Cully,³⁵S. DaRonco,⁴³M. Datta,¹⁷S. D’Auria,²¹T. Davies,²¹

D. Dagenhart,¹⁷P. de Barbaro,⁴⁹S. De Cecco,⁵¹A. Deisher,²⁹G. De Lentdecker,^49,cG. De Lorenzo,³M. Dell’Orso,⁴⁶ F. Delli Paoli,⁴³L. Demortier,⁵⁰J. Deng,¹⁶M. Deninno,⁵D. De Pedis,⁵¹P. F. Derwent,¹⁷G. P. Di Giovanni,⁴⁴C. Dionisi,⁵¹

B. Di Ruzza,⁵⁴J. R. Dittmann,⁴M. D’Onofrio,³C. Do¨rr,²⁶S. Donati,⁴⁶P. Dong,⁸J. Donini,⁴³T. Dorigo,⁴³S. Dube,⁵² J. Efron,³⁹R. Erbacher,⁷D. Errede,²⁴S. Errede,²⁴R. Eusebi,¹⁷H. C. Fang,²⁹S. Farrington,³⁰I. Fedorko,⁴⁶W. T. Fedorko,¹³

R. G. Feild,⁶⁰M. Feindt,²⁶J. P. Fernandez,³²R. Field,¹⁸G. Flanagan,⁴⁸R. Forrest,⁷S. Forrester,⁷M. Franklin,²² J. C. Freeman,²⁹I. Furic,¹³M. Gallinaro,⁵⁰J. Galyardt,¹²J. E. Garcia,⁴⁶F. Garberson,¹⁰A. F. Garfinkel,⁴⁸C. Gay,⁶⁰ H. Gerberich,²⁴D. Gerdes,³⁵S. Giagu,⁵¹P. Giannetti,⁴⁶K. Gibson,⁴⁷J. L. Gimmell,⁴⁹C. Ginsburg,¹⁷N. Giokaris,^15,a M. Giordani,⁵⁴P. Giromini,¹⁹M. Giunta,⁴⁶G. Giurgiu,²⁵V. Glagolev,¹⁵D. Glenzinski,¹⁷M. Gold,³⁷N. Goldschmidt,¹⁸

J. Goldstein,^42,bA. Golossanov,¹⁷G. Gomez,¹¹G. Gomez-Ceballos,³³M. Goncharov,⁵³O. Gonza´lez,³²I. Gorelov,³⁷ A. T. Goshaw,¹⁶K. Goulianos,⁵⁰A. Gresele,⁴³S. Grinstein,²²C. Grosso-Pilcher,¹³R. C. Group,¹⁷U. Grundler,²⁴ J. Guimaraes da Costa,²²Z. Gunay-Unalan,³⁶C. Haber,²⁹K. Hahn,³³S. R. Hahn,¹⁷E. Halkiadakis,⁵²A. Hamilton,²⁰

B.-Y. Han,⁴⁹J. Y. Han,⁴⁹R. Handler,⁵⁹F. Happacher,¹⁹K. Hara,⁵⁵D. Hare,⁵²M. Hare,⁵⁶S. Harper,⁴²R. F. Harr,⁵⁸ R. M. Harris,¹⁷M. Hartz,⁴⁷K. Hatakeyama,⁵⁰J. Hauser,⁸C. Hays,⁴²M. Heck,²⁶A. Heijboer,⁴⁵B. Heinemann,²⁹ J. Heinrich,⁴⁵C. Henderson,³³M. Herndon,⁵⁹J. Heuser,²⁶D. Hidas,¹⁶C. S. Hill,^10,bD. Hirschbuehl,²⁶A. Hocker,¹⁷

A. Holloway,²²S. Hou,¹M. Houlden,³⁰S.-C. Hsu,⁹B. T. Huffman,⁴²R. E. Hughes,³⁹U. Husemann,⁶⁰J. Huston,³⁶ J. Incandela,¹⁰G. Introzzi,⁴⁶M. Iori,⁵¹A. Ivanov,⁷B. Iyutin,³³E. James,¹⁷D. Jang,⁵²B. Jayatilaka,¹⁶D. Jeans,⁵¹ E. J. Jeon,²⁸S. Jindariani,¹⁸W. Johnson,⁷M. Jones,⁴⁸K. K. Joo,²⁸S. Y. Jun,¹²J. E. Jung,²⁸T. R. Junk,²⁴T. Kamon,⁵³

P. E. Karchin,⁵⁸Y. Kato,⁴¹Y. Kemp,²⁶R. Kephart,¹⁷U. Kerzel,²⁶V. Khotilovich,⁵³B. Kilminster,³⁹D. H. Kim,²⁸ H. S. Kim,²⁸J. E. Kim,²⁸M. J. Kim,¹⁷S. B. Kim,²⁸S. H. Kim,⁵⁵Y. K. Kim,¹³N. Kimura,⁵⁵L. Kirsch,⁶S. Klimenko,¹⁸

M. Klute,³³B. Knuteson,³³B. R. Ko,¹⁶K. Kondo,⁵⁷D. J. Kong,²⁸J. Konigsberg,¹⁸A. Korytov,¹⁸A. V. Kotwal,¹⁶ A. C. Kraan,⁴⁵J. Kraus,²⁴M. Kreps,²⁶J. Kroll,⁴⁵N. Krumnack,⁴M. Kruse,¹⁶V. Krutelyov,¹⁰T. Kubo,⁵⁵S. E. Kuhlmann,²

T. Kuhr,²⁶N. P. Kulkarni,⁵⁸Y. Kusakabe,⁵⁷S. Kwang,¹³A. T. Laasanen,⁴⁸S. Lai,³⁴S. Lami,⁴⁶S. Lammel,¹⁷ M. Lancaster,³¹R. L. Lander,⁷K. Lannon,³⁹A. Lath,⁵²G. Latino,⁴⁶I. Lazzizzera,⁴³T. LeCompte,²J. Lee,⁴⁹J. Lee,²⁸

Y. J. Lee,²⁸S. W. Lee,^53,oR. Lefe`vre,²⁰N. Leonardo,³³S. Leone,⁴⁶S. Levy,¹³J. D. Lewis,¹⁷C. Lin,⁶⁰C. S. Lin,¹⁷ M. Lindgren,¹⁷E. Lipeles,⁹A. Lister,⁷D. O. Litvintsev,¹⁷T. Liu,¹⁷N. S. Lockyer,⁴⁵A. Loginov,⁶⁰M. Loreti,⁴³R.-S. Lu,¹

D. Lucchesi,⁴³P. Lujan,²⁹P. Lukens,¹⁷G. Lungu,¹⁸L. Lyons,⁴²J. Lys,²⁹R. Lysak,¹⁴E. Lytken,⁴⁸P. Mack,²⁶ D. MacQueen,³⁴R. Madrak,¹⁷K. Maeshima,¹⁷K. Makhoul,³³T. Maki,²³P. Maksimovic,²⁵S. Malde,⁴²S. Malik,³¹

G. Manca,³⁰F. Margaroli,⁵R. Marginean,¹⁷C. Marino,²⁶C. P. Marino,²⁴A. Martin,⁶⁰M. Martin,²⁵V. Martin,^21,g M. Martı´nez,³R. Martı´nez-Balları´n,³²T. Maruyama,⁵⁵P. Mastrandrea,⁵¹T. Masubuchi,⁵⁵H. Matsunaga,⁵⁵ M. E. Mattson,⁵⁸R. Mazini,³⁴P. Mazzanti,⁵K. S. McFarland,⁴⁹P. McIntyre,⁵³R. McNulty,^30,fA. Mehta,³⁰P. Mehtala,²³

S. Menzemer,^11,hA. Menzione,⁴⁶P. Merkel,⁴⁸C. Mesropian,⁵⁰A. Messina,³⁶T. Miao,¹⁷N. Miladinovic,⁶J. Miles,³³ R. Miller,³⁶C. Mills,¹⁰M. Milnik,²⁶A. Mitra,¹G. Mitselmakher,¹⁸A. Miyamoto,²⁷S. Moed,²⁰N. Moggi,⁵B. Mohr,⁸

C. S. Moon,²⁸R. Moore,¹⁷M. Morello,⁴⁶P. Movilla Fernandez,²⁹J. Mu¨lmensta¨dt,²⁹A. Mukherjee,¹⁷Th. Muller,²⁶

R. Mumford,²⁵P. Murat,¹⁷M. Mussini,⁵J. Nachtman,¹⁷A. Nagano,⁵⁵J. Naganoma,⁵⁷K. Nakamura,⁵⁵I. Nakano,⁴⁰ A. Napier,⁵⁶V. Necula,¹⁶C. Neu,⁴⁵M. S. Neubauer,⁹J. Nielsen,^29,nL. Nodulman,²O. Norniella,³E. Nurse,³¹S. H. Oh,¹⁶

Y. D. Oh,²⁸I. Oksuzian,¹⁸T. Okusawa,⁴¹R. Oldeman,³⁰R. Orava,²³K. Osterberg,²³C. Pagliarone,⁴⁶E. Palencia,¹¹ V. Papadimitriou,¹⁷A. Papaikonomou,²⁶A. A. Paramonov,¹³B. Parks,³⁹S. Pashapour,³⁴J. Patrick,¹⁷G. Pauletta,⁵⁴ M. Paulini,¹²C. Paus,³³D. E. Pellett,⁷A. Penzo,⁵⁴T. J. Phillips,¹⁶G. Piacentino,⁴⁶J. Piedra,⁴⁴L. Pinera,¹⁸K. Pitts,²⁴

C. Plager,⁸L. Pondrom,⁵⁹X. Portell,³O. Poukhov,¹⁵N. Pounder,⁴²F. Prakoshyn,¹⁵A. Pronko,¹⁷J. Proudfoot,² F. Ptohos,^19,eG. Punzi,⁴⁶J. Pursley,²⁵J. Rademacker,^42,bA. Rahaman,⁴⁷V. Ramakrishnan,⁵⁹N. Ranjan,⁴⁸I. Redondo,³² B. Reisert,¹⁷V. Rekovic,³⁷P. Renton,⁴²M. Rescigno,⁵¹S. Richter,²⁶F. Rimondi,⁵L. Ristori,⁴⁶A. Robson,²¹T. Rodrigo,¹¹ E. Rogers,²⁴S. Rolli,⁵⁶R. Roser,¹⁷M. Rossi,⁵⁴R. Rossin,¹⁰P. Roy,³⁴A. Ruiz,¹¹J. Russ,¹²V. Rusu,¹³H. Saarikko,²³ A. Safonov,⁵³W. K. Sakumoto,⁴⁹G. Salamanna,⁵¹O. Salto´,³L. Santi,⁵⁴S. Sarkar,⁵¹L. Sartori,⁴⁶K. Sato,¹⁷P. Savard,³⁴

A. Savoy-Navarro,⁴⁴T. Scheidle,²⁶P. Schlabach,¹⁷E. E. Schmidt,¹⁷M. P. Schmidt,⁶⁰M. Schmitt,³⁸T. Schwarz,⁷ L. Scodellaro,¹¹A. L. Scott,¹⁰A. Scribano,⁴⁶F. Scuri,⁴⁶A. Sedov,⁴⁸S. Seidel,³⁷Y. Seiya,⁴¹A. Semenov,¹⁵ L. Sexton-Kennedy,¹⁷A. Sfyrla,²⁰S. Z. Shalhout,⁵⁸M. D. Shapiro,²⁹T. Shears,³⁰P. F. Shepard,⁴⁷D. Sherman,²² M. Shimojima,^55,kM. Shochet,¹³Y. Shon,⁵⁹I. Shreyber,²⁰A. Sidoti,⁴⁶P. Sinervo,³⁴A. Sisakyan,¹⁵A. J. Slaughter,¹⁷ J. Slaunwhite,³⁹K. Sliwa,⁵⁶J. R. Smith,⁷F. D. Snider,¹⁷R. Snihur,³⁴M. Soderberg,³⁵A. Soha,⁷S. Somalwar,⁵²V. Sorin,³⁶

J. Spalding,¹⁷F. Spinella,⁴⁶T. Spreitzer,³⁴P. Squillacioti,⁴⁶M. Stanitzki,⁶⁰A. Staveris-Polykalas,⁴⁶R. St. Denis,²¹ B. Stelzer,⁸O. Stelzer-Chilton,⁴²D. Stentz,³⁸J. Strologas,³⁷D. Stuart,¹⁰J. S. Suh,²⁸A. Sukhanov,¹⁸H. Sun,⁵⁶I. Suslov,¹⁵

T. Suzuki,⁵⁵A. Taffard,^24,pR. Takashima,⁴⁰Y. Takeuchi,⁵⁵R. Tanaka,⁴⁰M. Tecchio,³⁵P. K. Teng,¹K. Terashi,⁵⁰ J. Thom,^17,dA. S. Thompson,²¹E. Thomson,⁴⁵P. Tipton,⁶⁰V. Tiwari,¹²S. Tkaczyk,¹⁷D. Toback,⁵³S. Tokar,¹⁴ K. Tollefson,³⁶T. Tomura,⁵⁵D. Tonelli,⁴⁶S. Torre,¹⁹D. Torretta,¹⁷S. Tourneur,⁴⁴W. Trischuk,³⁴R. Tsuchiya,⁵⁷ S. Tsuno,⁴⁰Y. Tu,⁴⁵N. Turini,⁴⁶F. Ukegawa,⁵⁵S. Uozumi,⁵⁵S. Vallecorsa,²⁰N. van Remortel,²³A. Varganov,³⁵ E. Vataga,³⁷F. Va´zquez,^18,iG. Velev,¹⁷G. Veramendi,²⁴V. Veszpremi,⁴⁸M. Vidal,³²R. Vidal,¹⁷I. Vila,¹¹R. Vilar,¹¹

T. Vine,³¹I. Vollrath,³⁴I. Volobouev,^29,oG. Volpi,⁴⁶F. Wu¨rthwein,⁹P. Wagner,⁵³R. G. Wagner,²R. L. Wagner,¹⁷ J. Wagner,²⁶W. Wagner,²⁶R. Wallny,⁸S. M. Wang,¹A. Warburton,³⁴D. Waters,³¹M. Weinberger,⁵³W. C. Wester III,¹⁷

B. Whitehouse,⁵⁶D. Whiteson,⁴⁵A. B. Wicklund,²E. Wicklund,¹⁷G. Williams,³⁴H. H. Williams,⁴⁵P. Wilson,¹⁷ B. L. Winer,³⁹P. Wittich,^17,dS. Wolbers,¹⁷C. Wolfe,¹³T. Wright,³⁵X. Wu,²⁰S. M. Wynne,³⁰A. Yagil,⁹K. Yamamoto,⁴¹

J. Yamaoka,⁵²T. Yamashita,⁴⁰C. Yang,⁶⁰U. K. Yang,^13,jY. C. Yang,²⁸W. M. Yao,²⁹G. P. Yeh,¹⁷J. Yoh,¹⁷K. Yorita,¹³ T. Yoshida,⁴¹G. B. Yu,⁴⁹I. Yu,²⁸S. S. Yu,¹⁷J. C. Yun,¹⁷L. Zanello,⁵¹A. Zanetti,⁵⁴I. Zaw,²²

X. Zhang,²⁴J. Zhou,⁵²and S. Zucchelli⁵ (CDF Collaboration)

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, and Institute of Experimental Physics, 040 01 Kosice, Slovakia

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

16Duke University, Durham, North Carolina 27708, USA

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

132001-2

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

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;

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, Montr´eal, 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

37University of New Mexico, Albuquerque, New Mexico 87131, USA

38Northwestern University, Evanston, Illinois 60208, USA

39The Ohio State University, Columbus, Ohio 43210, USA

40Okayama University, Okayama 700-8530, Japan

41Osaka City University, Osaka 588, Japan

42University of Oxford, Oxford OX1 3RH, United Kingdom

43University of Padova, Istituto Nazionale di Fisica Nucleare, Sezione di Padova-Trento, I-35131 Padova, Italy

44LPNHE, Universite Pierre et Marie Curie/IN2P3-CNRS, UMR7585, Paris, F-75252 France

45University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA

46Istituto Nazionale di Fisica Nucleare Pisa, Universities of Pisa, Siena and Scuola Normale Superiore, I-56127 Pisa, Italy

47University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA

48Purdue University, West Lafayette, Indiana 47907, USA

49University of Rochester, Rochester, New York 14627, USA

50The Rockefeller University, New York, New York 10021, USA

51Istituto Nazionale di Fisica Nucleare, Sezione di Roma 1, University of Rome ‘‘La Sapienza,’’ I-00185 Roma, Italy

52Rutgers University, Piscataway, New Jersey 08855, USA

53Texas A&M University, College Station, Texas 77843, USA

54Istituto Nazionale di Fisica Nucleare, University of Trieste/Udine, Italy

55University of Tsukuba, Tsukuba, Ibaraki 305, Japan

56Tufts University, Medford, Massachusetts 02155, USA

57Waseda University, Tokyo 169, Japan

58Wayne State University, Detroit, Michigan 48201, USA

59University of Wisconsin, Madison, Wisconsin 53706, USA

60Yale University, New Haven, Connecticut 06520, USA (Received 3 April 2007; published 26 September 2007)

We have measured the polarizations of J= and 2S mesons as functions of their transverse momentump_T when they are produced promptly in the rapidity range jyj<0:6with p_T5 GeV=c.

The analysis is performed using a data sample with an integrated luminosity of about800 pb¹collected by the CDF II detector. For both vector mesons, we find that the polarizations become increasingly longitudinal as pT increases from 5 to 30 GeV=c. These results are compared to the predictions of nonrelativistic quantum chromodynamics and other contemporary models. The effective polarizations of J= and 2Smesons fromB-hadron decays are also reported.

DOI:10.1103/PhysRevLett.99.132001 PACS numbers: 13.88.+e, 13.20.Gd, 14.40.Lb

An effective field theory, nonrelativistic quantum chro- modynamics (NRQCD) [1], provides a rigorous formalism for calculating the production rates of charmonium (cc) states. NRQCD explains the direct production cross sec- tions forJ= and 2Smesons observed at the Tevatron [2,3] and predicts their increasingly transverse polariza-

tions asp_T increases, wherep_T is the meson’s momentum component perpendicular to the colliding beam direction [4]. The first polarization measurements at the Tevatron [5]

did not show such a trend. This Letter reports onJ= and 2Spolarization measurements with a larger data sample than previously available. This allows the extension of the

measurement to a higher p_T region and makes a more stringent test of the NRQCD prediction.

The NRQCD cross section calculation forccproduction separates the long-distance nonperturbative contributions from the short-distance perturbative behavior. The former is treated as an expansion of the matrix elements in powers of the nonrelativistic charm-quark velocity. This expansion can be computed by lattice simulations, but currently the expansion coefficients are treated as universal parameters, which are adjusted to match the cross section measure- ments at the Tevatron [2,3]. The calculation also applies to ccproduction inepcollisions, but HERA measurements of J= polarization tend to disagree with the NRQCD pre- diction [6]. These difficulties have led some authors to explore alternative power expansions of the long-distance interactions for the cc system [7]. There are also new QCD-inspired models, the gluon tower model [8] and the k_T-factorization model [9], that accomodate vector-meson cross sections at both HERA and the Tevatron and predict the vector-meson polarizations as functions ofp_T. These authors emphasize that measuring the vector-meson polar- izations as functions ofp_T is a crucial test of NRQCD.

The CDF II detector is described in detail elsewhere [3,10]. In this analysis, the essential features are a muon system covering the central region of pseudorapidity, jj<0:6, and the tracking system, immersed in the 1.4 T solenoidal magnetic field and composed of a silicon microstrip detector and a cylindrical drift chamber called the central outer tracker (COT). The data used here corre- spond to an integrated luminosity of about 800 pb¹ and were recorded between June 2004 and February 2006 by a dimuon trigger, which requires two opposite-charge muon candidates, each havingp_T >1:5 GeV=c.

Decays of vector mesonsV [either J= or 2S] ! are selected from dimuon events for which each

track has segments reconstructed in both the COT and the silicon microstrip detector. The p_T of each muon is re- quired to exceed1:75 GeV=cin order to guarantee a well- measured trigger efficiency. The muon track pair is re- quired to be consistent with originating from a common vertex and to have an invariant mass M within the range 2:83:4< M <3:43:9GeV=c² to be considered as a J= [ 2S] candidate. To have a reasonable polarization sensitivity, the vector-meson candidates are required to have p_T 5 GeV=cin the rapidity rangejyf¹₂ lnE pk=Epk gj<0:6, whereEis the energy andpkis the momentum parallel to the beam direction of the dimuon system. Events are separated into a signal region and sideband regions, as indicated in Fig. 1. The fit to the data uses a double (single) Gaussian for the J= [ 2S]

signal and a linear background shape. The fits are used only to define signal and background regions. The signal regions are within 3_V of the fitted mass peaksM_V, where_V is the width obtained in the fit to the invariant mass distribu- tion. Both the background distribution and the quantity of background events under the signal peak are estimated by events from the lower and upper mass sidebands. The sideband regions are7_J= (4 _2S) away from the signal region forJ= [ 2S].

For each candidate, we computectML_xy=p_T, wheret is the proper decay time andL_xyis the transverse distance between the beam line and the decay vertex in the plane normal to the beam direction. The ctdistributions of the selected dimuon events are shown in Fig.2. Thectdistri- bution of prompt events is a Gaussian distribution centered at zero due to finite tracking resolution. For J= , the prompt events are due to direct production or the decays of heavier charmonium states such as _c and 2S; for 2S, the prompt events are almost entirely due to direct production since heavier charmonium states rarely decay

2) M (GeV/c

2.8 2.9 3 3.1 3.2 3.3 3.4

2 Events / 0.005 GeV/c

0 20 40 60 80 100 120 140

103

×

(a)

2) M (GeV/c

3.4 3.5 3.6 3.7 3.8 3.9

2 Events / 0.005 GeV/c

0 1000 2000 3000 4000 5000

(b)

FIG. 1 (color online). Invariant mass distributions for (a)J= and (b) 2Scandidates. The curves are fits to the data. The solid (dashed) lines indicate the signal (sideband) regions.

132001-4

to 2S[11]. Both theJ= and the 2Ssamples contain significant numbers of events originating from long-lived B-hadron decays, as can be seen from the event excess at positivect. We have measured the fraction ofB!J=

X events in the J= sample and found agreement with other results [3]. We select prompt events by requiring the sum of the squared impact parameter significances of the positively and negatively charged muon tracks S d₀=² d₀=²8. The impact parameter d₀ is the distance of closest approach of the track to the beam line in the transverse plane. Vector-meson candidates from B-hadron decays are selected by requiringS >16andct >

0:03 cm. This requirement retains a negligible fraction of prompt events in theBsample.

To measure the polarizations of promptJ= and 2S mesons as functions ofp_T, theJ= events are analyzed in six p_T bins and the 2S events in three bins, shown in TableI. We determine the fraction ofB-decay background remaining in prompt samplesf_bkd by subtracting the num- ber of negative ctevents from the number of positive ct events. Only a negligible fraction (<0:2%) of B decays

produce vector-meson events with negative ct. For both vector mesons,f_bkd increases withp_T, as listed in TableI.

The prompt polarization from the fitting algorithm is cor- rected for this contamination.

The polarization information is contained in the distri- bution of the muon decay angle, the angle of thein the rest frame of the vector meson with respect to the vector-meson boost direction in the laboratory system.

The decay angle distribution depends on the polarization parameter : dN=dcos/1cos² (11).

For fully transverse (longitudinal) polarization, 11. Intermediate values of indicate a mixture of transverse and longitudinal polarization.

A template method is used to account for acceptance and efficiency. Two sets ofcos distributions for fully polar- ized decays ofJ= and 2Sevents, one longitudinal (L) and the other transverse (T), are produced with the CDF simulation program using the efficiency-corrected p_T spectra measured from data [3,12]. We use the muon trigger efficiency measured using data as a function of track parameters (p_T,,) to account for detector non- ct (cm)

-0.3 -0.2 -0.1 0 0.1 0.2 0.3

Events / 0.002 cm

1 10 102

103

104

105

(a)

ct (cm)

-0.2 -0.1 0 0.1 0.2

Events / 0.004 cm

1 10 102

103

104

(b)

FIG. 2 (color online). Sideband-subtractedctdistributions for (a)J= and (b) 2Sevents. The prompt Gaussian peak, positive excess fromB-hadron decays, and negative tail from mismeasured events are shown. The dotted line is the reflection of the negativect histogram about zero.

TABLE I. Polarization parameterfor prompt production in eachpTbin. The first (second) uncertainty is statistical (systematic).

hp_Tiis the average transverse momentum.

p_T (GeV=c) hp_Ti(GeV=c) f_bkd(%) ²=d:o:f

J= 5– 6 5.5 2:80:2 0:0040:0290:009 15:5=21 6 –7 6.5 3:40:2 0:0150:0280:010 24:1=23 7– 9 7.8 4:10:2 0:0770:0230:013 35:1=25

9 –12 10.1 5:70:3 0:0940:0280:007 34:0=29

12 –17 13.7 6:70:6 0:1400:0430:007 35:0=31

17– 30 20.0 13:61:4 0:1870:0900:007 33:9=35

2S 5–7 5.9 1:60:9 0:3140:2420:028 13:1=11 7–10 8.2 4:91:2 0:0130:2010:035 18:5=13

10 – 30 12.6 8:61:8 0:3740:2220:062 26:9=17

uniformities. The parametrized efficiency is used as a filter on all simulated muons. Events that pass reconstruction represent the behavior of fully polarized vector-meson decays in the detector.

The fitting algorithm [5] uses two binned cos distri- butions for eachp_T bin, one made byN_Sevents from the signal region (signal plus background) and the other made byN_Bevents from the sideband regions (background). The ² minimization is done simultaneously for both cos distributions. The fitting algorithm includes an individual background term for each cos bin, normalized to N_B. Simulation shows that the cos resolution at all decay angles over the entirep_Trange is much smaller than the bin width of 0.05 [0.10 for 2S] used here. The data, fit, and template distributions for the worst fit (9% probability) in theJ= data are shown in Fig.3.

All systematic uncertainties are much smaller than the statistical uncertainties. Varying the p_T spectrum used in the simulation by1 changed the polarization parameter forJ= at most by 0.002. A systematic uncertainty of 0.007 was estimated by the change in the polarization parameter when a modification was made on all trigger efficiencies by 1. For 2S, the dominant systematic uncertainty came from the yield estimate because of the radiative tail and the large background. The total systematic uncertain- ties shown in TableIwere taken to be the quadrature sum of these individual uncertainties. Other possible sources of systematic uncertainties —signal definition andcosbin- ning — were determined to be negligible. Corrections to prompt polarization from B-decay contamination were small, so that uncertainties onB-decay polarization mea- surements also had negligible effect. Nodependence of the polarizations was observed.

The polarization ofJ= mesons from inclusiveB_u and B_d decays was measured by the BABAR Collaboration [13]. In this analysis, theB-hadron direction is unknown, so we define with respect to the J= direction in the

laboratory system. The resulting polarization is somewhat diluted. As discussed in Ref. [3], CDF uses a Monte Carlo procedure to adapt theBABARmeasurement to predict the effective J= polarization parameter. For the J= events with5p_T<30 GeV=c, the CDF model for B_uandB_d decays gives _eff 0:1450:009, independent of p_T. We have measured the polarization of vector mesons from B-hadron decays. For J= , we find _eff 0:106 0:033stat 0:007syst. At this level of accuracy, a po- larization contribution by J= mesons from B_s and b-baryon decays cannot be separated from the effective polarization due to those fromB_uandB_ddecays. We also report the first measurement of the 2Spolarization from B-hadron decays:_eff 0:360:25stat 0:03syst.

The polarization parameters for both prompt vector mesons corrected for f_bkd using our experimental results on _eff are listed as functions of p_T in Table I and are plotted in Fig. 4. The polarization parameters forJ= are negative over the entire p_T range of measurement and become increasingly negative (favoring longitudinal polar- ization) asp_Tincreases. For 2S, the central value of the polarization parameter is positive at small p_T, but, given the uncertainties, its behavior is consistent with the trend shown in the measurement of theJ= polarization.

The polarization behavior measured previously with 110 pb¹ [5] is not consistent with the results presented here. This is a differential measurement, and the muon efficiencies in this analysis are true dimuon efficiencies.

In Ref. [5], they are the product of independent single muon efficiencies. The efficiency for muons with p_T<

4 GeV=cis crucial for good polarization sensitivity. In this analysis, the muon efficiency varies smoothly from 99% to 97% over this range. In the analysis of Ref. [5], it varied from 93% to 40% with significant jumps between individ- ual data points. Data from periods of drift chamber aging were omitted from this analysis because the polarization results were inconsistent with the remainder of the data.

Studies such as this were not done in the analysis of Ref. [5]. The systematics of the polarization measurement are much better understood in this analysis.

These polarization measurements for the charmed vec- tor mesons extend to ap_Tregime where perturbative QCD should be applicable. The results are compared to the predictions of NRQCD and the k_T-factorization model in Fig. 4. The prediction of the k_T-factorization model is presented for p_T<20 GeV=c and does not include the contribution from the decays of heavier charmonium states forJ= production. The polarizations for prompt produc- tion of both vector mesons become increasingly longitudi- nal asp_T increases beyond10 GeV=c. This behavior is in strong disagreement with the NRQCD prediction of large transverse polarization at high p_T. It is striking that the NRQCD calculation and the other models reproduce the measuredJ= and 2Scross sections at the Tevatron but fail to describe the polarization at highp_T. This indicates θ*

cos

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1

Events / 0.05

0 0.01 0.02 0.03 0.04 0.05

(GeV/c) < 9 pT

≤ 7

Data T L Fit

FIG. 3 (color online). cos distribution of data (points) and polarization fit for the worst²probability bin in theJ= data.

The dotted (dashed) line is the template for fullyL (T) polar- ization. The fit describes the overall trend of the data well.

132001-6

that there is some important aspect of the production mechanism that is not yet understood.

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 Founda- tion; the A. P. Sloan Foundation; the Bundesministerium 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, United Kingdom; 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; the Slovak R&D Agency; and the Academy of Finland.

aVisiting scientist from University of Athens.

bVisiting scientist from University of Bristol.

cVisiting scientist from University Libre de Bruxelles.

dVisiting scientist from Cornell University.

eVisiting scientist from University of Cyprus.

fVisiting scientist from University of Dublin.

gVisiting scientist from University of Edinburgh.

hVisiting scientist from University of Heidelberg.

iVisiting scientist from Universidad Iberoamericana.

jVisiting scientist from University of Manchester.

kVisiting scientist from Nagasaki Institute of Applied Science.

lVisiting scientist from University de Oviedo.

mVisiting scientist from University of London, Queen Mary College.

nVisiting scientist from University of California, Santa Cruz.

oVisiting scientist from Texas Tech University.

pVisiting scientist from University of California, Irvine.

qVisiting scientist from IFIC(CSIC-Universitat de Valencia).

[1] G. T. Bodwin, E. Braaten, and G. P. Lepage, Phys. Rev. D 51, 1125 (1995); 55, 5853 (1997); E. Braaten and S. Fleming, Phys. Rev. Lett.74, 3327 (1995).

[2] F. Abeet al.(CDF Collaboration), Phys. Rev. Lett.79, 572 (1997).

[3] D. Acosta et al.(CDF Collaboration), Phys. Rev. D71, 032001 (2005).

[4] P. Cho and M. Wise, Phys. Lett. B 346, 129 (1995);

M. Beneke and I. Z. Rothstein, Phys. Lett. B 372, 157 (1996); 389, 769 (1996); E. Braaten, B. A. Kniehl, and J. Lee, Phys. Rev. D62, 094005 (2000).

[5] T. Affolderet al.(CDF Collaboration), Phys. Rev. Lett.85, 2886 (2000).

[6] C. Adloffet al.(H1 Collaboration), Eur. Phys. J. C25, 41 (2002); S. Chekanov et al. (ZEUS Collaboration), Eur.

Phys. J. C44, 13 (2005).

[7] S. Fleming, I. Z. Rothstein, and A. K. Leibovich, Phys.

Rev. D64, 036002 (2001).

[8] V. A. Khoze, A. D. Martin, M. G. Ryskin, and W. J.

Stirling, Eur. Phys. J. C39, 163 (2005).

[9] S. P. Baranov, Phys. Rev. D66, 114003 (2002).

[10] The CDF coordinate system hasz^along the proton direc- tion,x^horizontal pointing outward from the Tevatron ring, and y^ vertical. () is the polar (azimuthal) angle measured with respect toz, and^ is the pseudorapidity defined aslntan=2 . The transverse momentum of a particle is denoted asp_Tpsin.

[11] W.-M. Yaoet al.(Particle Data Group), J. Phys. G33, 1 (2006).

[12] A Letter on 2Scross section measurement is in prepa- ration.

[13] B. Aubertet al.(BABARCollaboration), Phys. Rev. D67, 032002 (2003).

(GeV/c) pT

5 10 15 20 25 30

α

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1

CDF Data NRQCD

-factorization kT

(a)

(GeV/c) pT

5 10 15 20 25 30

α

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1

CDF Data NRQCD

-factorization kT

(b)

FIG. 4 (color online). Prompt polarizations as functions ofp_T: (a)J= and (b) 2S. The band (line) is the prediction from NRQCD [4] (thekT-factorization model [9]).