Search for the Charmed Pentaquark Candidate $\Theta_c (3100)^0$ in $e^+e^-$ Annihilations at $\sqrt{s}=10.58 GeV$

arXiv:hep-ex/0604006v2 22 May 2006

B B -PUB-06/007 hep-ex/0604006

Search for the Charmed Pentaquark Candidate Θ

(3100)

0

_{in e}

_e

Annihilations at

√

s

= 10.58 GeV

B. Aubert,1 _{R. Barate,}1 _{M. Bona,}1_{D. Boutigny,}1 _{F. Couderc,}1 _{Y. Karyotakis,}1 _{J. P. Lees,}1 _{V. Poireau,}1 V. Tisserand,1 _{A. Zghiche,}1 _{E. Grauges,}2_{A. Palano,}3_{M. Pappagallo,}3_{J. C. Chen,}4_{N. D. Qi,}4 _{G. Rong,}4 _{P. Wang,}4

Y. S. Zhu,4 _{G. Eigen,}5 _{I. Ofte,}5_{B. Stugu,}5 _{G. S. Abrams,}6 _{M. Battaglia,}6_{D. N. Brown,}6 _{J. Button-Shafer,}6 R. N. Cahn,6 _{E. Charles,}6_{C. T. Day,}6 _{M. S. Gill,}6 _{Y. Groysman,}6_{R. G. Jacobsen,}6 _{J. A. Kadyk,}6_{L. T. Kerth,}6

Yu. G. Kolomensky,6G. Kukartsev,6 G. Lynch,6 L. M. Mir,6 P. J. Oddone,6 T. J. Orimoto,6M. Pripstein,6 N. A. Roe,6 _{M. T. Ronan,}6_{W. A. Wenzel,}6_{M. Barrett,}7_{K. E. Ford,}7_{T. J. Harrison,}7_{A. J. Hart,}7 _{C. M. Hawkes,}7

S. E. Morgan,7 _{A. T. Watson,}7 _{K. Goetzen,}8 _{T. Held,}8 _{H. Koch,}8 _{B. Lewandowski,}8 _{M. Pelizaeus,}8 _{K. Peters,}8 T. Schroeder,8_{M. Steinke,}8_{J. T. Boyd,}9 _{J. P. Burke,}9_{W. N. Cottingham,}9_{D. Walker,}9_{T. Cuhadar-Donszelmann,}10

B. G. Fulsom,10 _{C. Hearty,}10 _{N. S. Knecht,}10 _{T. S. Mattison,}10 _{J. A. McKenna,}10 _{A. Khan,}11 _{P. Kyberd,}11 M. Saleem,11 _{L. Teodorescu,}11_{V. E. Blinov,}12 _{A. D. Bukin,}12 _{V. P. Druzhinin,}12 _{V. B. Golubev,}12 _{A. P. Onuchin,}12

S. I. Serednyakov,12 _{Yu. I. Skovpen,}12 _{E. P. Solodov,}12 _{K. Yu Todyshev,}12 _{D. S. Best,}13 _{M. Bondioli,}13 M. Bruinsma,13_{M. Chao,}13_{S. Curry,}13_{I. Eschrich,}13 _{D. Kirkby,}13_{A. J. Lankford,}13 _{P. Lund,}13 _{M. Mandelkern,}13

R. K. Mommsen,13 _{W. Roethel,}13 _{D. P. Stoker,}13 _{S. Abachi,}14 _{C. Buchanan,}14_{S. D. Foulkes,}15 _{J. W. Gary,}15 O. Long,15 _{B. C. Shen,}15_{K. Wang,}15 _{L. Zhang,}15 _{H. K. Hadavand,}16 _{E. J. Hill,}16 _{H. P. Paar,}16_{S. Rahatlou,}16 V. Sharma,16_{J. W. Berryhill,}17 _{C. Campagnari,}17 _{A. Cunha,}17 _{B. Dahmes,}17 _{T. M. Hong,}17_{D. Kovalskyi,}17 J. D. Richman,17_{T. W. Beck,}18 _{A. M. Eisner,}18_{C. J. Flacco,}18 _{C. A. Heusch,}18 _{J. Kroseberg,}18 _{W. S. Lockman,}18

G. Nesom,18 _{T. Schalk,}18 _{B. A. Schumm,}18 _{A. Seiden,}18 _{P. Spradlin,}18 _{D. C. Williams,}18 _{M. G. Wilson,}18 J. Albert,19 _{E. Chen,}19 _{A. Dvoretskii,}19 _{D. G. Hitlin,}19 _{I. Narsky,}19_{T. Piatenko,}19 _{F. C. Porter,}19 _{A. Ryd,}19 A. Samuel,19 _{R. Andreassen,}20 _{G. Mancinelli,}20 _{B. T. Meadows,}20_{M. D. Sokoloff,}20 _{F. Blanc,}21 _{P. C. Bloom,}21

S. Chen,21 _{W. T. Ford,}21 _{J. F. Hirschauer,}21_{A. Kreisel,}21_{U. Nauenberg,}21_{A. Olivas,}21_{W. O. Ruddick,}21 J. G. Smith,21_{K. A. Ulmer,}21 _{S. R. Wagner,}21_{J. Zhang,}21 _{A. Chen,}22 _{E. A. Eckhart,}22_{A. Soffer,}22_{W. H. Toki,}22 R. J. Wilson,22 _{F. Winklmeier,}22_{Q. Zeng,}22 _{D. D. Altenburg,}23_{E. Feltresi,}23 _{A. Hauke,}23_{H. Jasper,}23 _{B. Spaan,}23

T. Brandt,24 _{V. Klose,}24 _{H. M. Lacker,}24 _{W. F. Mader,}24 _{R. Nogowski,}24 _{A. Petzold,}24 _{J. Schubert,}24 K. R. Schubert,24 _{R. Schwierz,}24_{J. E. Sundermann,}24 _{A. Volk,}24_{D. Bernard,}25 _{G. R. Bonneaud,}25 _{P. Grenier,}25, ∗

E. Latour,25_{Ch. Thiebaux,}25 _{M. Verderi,}25 _{D. J. Bard,}26 _{P. J. Clark,}26 _{W. Gradl,}26 _{F. Muheim,}26 _{S. Playfer,}26 A. I. Robertson,26 _{Y. Xie,}26 _{M. Andreotti,}27 _{D. Bettoni,}27_{C. Bozzi,}27 _{R. Calabrese,}27 _{G. Cibinetto,}27 _{E. Luppi,}27

M. Negrini,27 _{A. Petrella,}27 _{L. Piemontese,}27 _{E. Prencipe,}27 _{F. Anulli,}28 _{R. Baldini-Ferroli,}28 _{A. Calcaterra,}28 R. de Sangro,28_{G. Finocchiaro,}28 _{S. Pacetti,}28 _{P. Patteri,}28_{I. M. Peruzzi,}28, † _{M. Piccolo,}28 _{M. Rama,}28 A. Zallo,28_{A. Buzzo,}29_{R. Capra,}29_{R. Contri,}29_{M. Lo Vetere,}29 _{M. M. Macri,}29_{M. R. Monge,}29 _{S. Passaggio,}29 C. Patrignani,29 _{E. Robutti,}29 _{A. Santroni,}29_{S. Tosi,}29 _{G. Brandenburg,}30 _{K. S. Chaisanguanthum,}30 _{M. Morii,}30 J. Wu,30 _{R. S. Dubitzky,}31 _{J. Marks,}31 _{S. Schenk,}31_{U. Uwer,}31 _{W. Bhimji,}32_{D. A. Bowerman,}32_{P. D. Dauncey,}32

U. Egede,32 _{R. L. Flack,}32_{J. R. Gaillard,}32 _{J .A. Nash,}32 _{M. B. Nikolich,}32_{W. Panduro Vazquez,}32 _{X. Chai,}33 M. J. Charles,33U. Mallik,33 N. T. Meyer,33 V. Ziegler,33J. Cochran,34 H. B. Crawley,34L. Dong,34V. Eyges,34

W. T. Meyer,34_{S. Prell,}34 _{E. I. Rosenberg,}34 _{A. E. Rubin,}34 _{A. V. Gritsan,}35 _{M. Fritsch,}36 _{G. Schott,}36 N. Arnaud,37 _{M. Davier,}37 _{G. Grosdidier,}37_{A. H¨ocker,}37 _{F. Le Diberder,}37 _{V. Lepeltier,}37 _{A. M. Lutz,}37 A. Oyanguren,37_{S. Pruvot,}37_{S. Rodier,}37 _{P. Roudeau,}37 _{M. H. Schune,}37 _{A. Stocchi,}37 _{W. F. Wang,}37 G. Wormser,37 _{C. H. Cheng,}38 _{D. J. Lange,}38 _{D. M. Wright,}38 _{C. A. Chavez,}39 _{I. J. Forster,}39 _{J. R. Fry,}39

E. Gabathuler,39 _{R. Gamet,}39 _{K. A. George,}39 _{D. E. Hutchcroft,}39 _{D. J. Payne,}39 _{K. C. Schofield,}39 C. Touramanis,39 _{A. J. Bevan,}40 _{F. Di Lodovico,}40 _{W. Menges,}40 _{R. Sacco,}40 _{C. L. Brown,}41_{G. Cowan,}41 H. U. Flaecher,41 _{D. A. Hopkins,}41_{P. S. Jackson,}41_{T. R. McMahon,}41_{S. Ricciardi,}41_{F. Salvatore,}41_{D. N. Brown,}42

C. L. Davis,42 _{J. Allison,}43 _{N. R. Barlow,}43 _{R. J. Barlow,}43 _{Y. M. Chia,}43 _{C. L. Edgar,}43_{M. P. Kelly,}43 G. D. Lafferty,43 _{M. T. Naisbit,}43 _{J. C. Williams,}43 _{J. I. Yi,}43 _{C. Chen,}44 _{W. D. Hulsbergen,}44 _{A. Jawahery,}44 C. K. Lae,44_{D. A. Roberts,}44_{G. Simi,}44_{G. Blaylock,}45_{C. Dallapiccola,}45_{S. S. Hertzbach,}45_{X. Li,}45 _{T. B. Moore,}45 S. Saremi,45 _{H. Staengle,}45_{S. Y. Willocq,}45 _{R. Cowan,}46_{K. Koeneke,}46 _{G. Sciolla,}46_{S. J. Sekula,}46_{M. Spitznagel,}46

F. Taylor,46_{R. K. Yamamoto,}46 _{H. Kim,}47 _{P. M. Patel,}47 _{C. T. Potter,}47 _{S. H. Robertson,}47 _{A. Lazzaro,}48 V. Lombardo,48_{F. Palombo,}48_{J. M. Bauer,}49 _{L. Cremaldi,}49 _{V. Eschenburg,}49_{R. Godang,}49 _{R. Kroeger,}49

J. Reidy,49_{D. A. Sanders,}49_{D. J. Summers,}49 _{H. W. Zhao,}49 _{S. Brunet,}50_{D. Cˆot´e,}50 _{M. Simard,}50_{P. Taras,}50 F. B. Viaud,50_{H. Nicholson,}51 _{N. Cavallo,}52, ‡_{G. De Nardo,}52 _{D. del Re,}52 _{F. Fabozzi,}52, ‡ _{C. Gatto,}52 _{L. Lista,}52

D. Monorchio,52 _{P. Paolucci,}52_{D. Piccolo,}52 _{C. Sciacca,}52 _{M. Baak,}53 _{H. Bulten,}53 _{G. Raven,}53_{H. L. Snoek,}53 C. P. Jessop,54 _{J. M. LoSecco,}54 _{T. Allmendinger,}55_{G. Benelli,}55 _{K. K. Gan,}55 _{K. Honscheid,}55 _{D. Hufnagel,}55 P. D. Jackson,55 _{H. Kagan,}55 _{R. Kass,}55_{T. Pulliam,}55 _{A. M. Rahimi,}55 _{R. Ter-Antonyan,}55 _{Q. K. Wong,}55

N. L. Blount,56 _{J. Brau,}56 _{R. Frey,}56 _{O. Igonkina,}56_{M. Lu,}56 _{R. Rahmat,}56 _{N. B. Sinev,}56 _{D. Strom,}56 J. Strube,56 _{E. Torrence,}56_{F. Galeazzi,}57_{A. Gaz,}57_{M. Margoni,}57 _{M. Morandin,}57_{A. Pompili,}57 _{M. Posocco,}57 M. Rotondo,57 F. Simonetto,57 R. Stroili,57 C. Voci,57M. Benayoun,58J. Chauveau,58P. David,58L. Del Buono,58

Ch. de la Vaissi`ere,58 <sub>O. Hamon,</sub>58<sub>B. L. Hartfiel,</sub>58<sub>M. J. J. John,</sub>58 <sub>Ph. Leruste,</sub>58 <sub>J. Malcl`es,</sub>58 _{J. Ocariz,}58 L. Roos,58 _{G. Therin,}58 _{P. K. Behera,}59 _{L. Gladney,}59 _{J. Panetta,}59_{M. Biasini,}60 _{R. Covarelli,}60 _{M. Pioppi,}60 C. Angelini,61 _{G. Batignani,}61 _{S. Bettarini,}61 _{F. Bucci,}61_{G. Calderini,}61 _{M. Carpinelli,}61 _{R. Cenci,}61 _{F. Forti,}61 M. A. Giorgi,61_{A. Lusiani,}61_{G. Marchiori,}61_{M. A. Mazur,}61_{M. Morganti,}61_{N. Neri,}61 _{E. Paoloni,}61_{G. Rizzo,}61 J. Walsh,61 _{M. Haire,}62_{D. Judd,}62_{D. E. Wagoner,}62_{J. Biesiada,}63_{N. Danielson,}63_{P. Elmer,}63_{Y. P. Lau,}63_{C. Lu,}63

J. Olsen,63 _{A. J. S. Smith,}63 _{A. V. Telnov,}63_{F. Bellini,}64_{G. Cavoto,}64_{A. D’Orazio,}64_{E. Di Marco,}64 _{R. Faccini,}64 F. Ferrarotto,64 _{F. Ferroni,}64_{M. Gaspero,}64 _{L. Li Gioi,}64 _{M. A. Mazzoni,}64_{S. Morganti,}64_{G. Piredda,}64_{F. Polci,}64 F. Safai Tehrani,64_{C. Voena,}64 _{M. Ebert,}65 _{H. Schr¨oder,}65_{R. Waldi,}65 _{T. Adye,}66_{N. De Groot,}66 _{B. Franek,}66

E. O. Olaiya,66_{F. F. Wilson,}66 _{S. Emery,}67_{A. Gaidot,}67 _{S. F. Ganzhur,}67 _{G. Hamel de Monchenault,}67 W. Kozanecki,67 _{M. Legendre,}67 _{B. Mayer,}67_{G. Vasseur,}67 _{Ch. Y`eche,}67_{M. Zito,}67 _{W. Park,}68_{M. V. Purohit,}68

A. W. Weidemann,68 _{J. R. Wilson,}68 _{M. T. Allen,}69 _{D. Aston,}69 _{R. Bartoldus,}69 _{P. Bechtle,}69_{N. Berger,}69 A. M. Boyarski,69 _{R. Claus,}69_{J. P. Coleman,}69_{M. R. Convery,}69_{M. Cristinziani,}69 _{J. C. Dingfelder,}69 _{D. Dong,}69 J. Dorfan,69G. P. Dubois-Felsmann,69D. Dujmic,69W. Dunwoodie,69R. C. Field,69T. Glanzman,69S. J. Gowdy,69

M. T. Graham,69 _{V. Halyo,}69 _{C. Hast,}69 _{T. Hryn’ova,}69 _{W. R. Innes,}69 _{M. H. Kelsey,}69 _{P. Kim,}69 _{M. L. Kocian,}69 D. W. G. S. Leith,69 _{S. Li,}69 _{J. Libby,}69 _{S. Luitz,}69_{V. Luth,}69_{H. L. Lynch,}69_{D. B. MacFarlane,}69 _{H. Marsiske,}69

R. Messner,69 D. R. Muller,69 C. P. O’Grady,69 V. E. Ozcan,69 A. Perazzo,69 M. Perl,69B. N. Ratcliff,69 A. Roodman,69 _{A. A. Salnikov,}69 _{R. H. Schindler,}69 _{J. Schwiening,}69 _{A. Snyder,}69 _{J. Stelzer,}69 _{D. Su,}69 M. K. Sullivan,69 _{K. Suzuki,}69 _{S. K. Swain,}69 _{J. M. Thompson,}69_{J. Va’vra,}69_{N. van Bakel,}69_{M. Weaver,}69 A. J. R. Weinstein,69 _{W. J. Wisniewski,}69_{M. Wittgen,}69 _{D. H. Wright,}69 _{A. K. Yarritu,}69_{K. Yi,}69_{C. C. Young,}69

P. R. Burchat,70 _{A. J. Edwards,}70 _{S. A. Majewski,}70_{B. A. Petersen,}70_{C. Roat,}70_{L. Wilden,}70 _{S. Ahmed,}71 M. S. Alam,71 _{R. Bula,}71 _{J. A. Ernst,}71 _{V. Jain,}71_{B. Pan,}71 _{M. A. Saeed,}71 _{F. R. Wappler,}71 _{S. B. Zain,}71 W. Bugg,72M. Krishnamurthy,72S. M. Spanier,72 R. Eckmann,73 J. L. Ritchie,73 A. Satpathy,73C. J. Schilling,73

R. F. Schwitters,73 _{J. M. Izen,}74 _{I. Kitayama,}74 _{X. C. Lou,}74 _{S. Ye,}74 _{F. Bianchi,}75 _{F. Gallo,}75_{D. Gamba,}75 M. Bomben,76 _{L. Bosisio,}76 _{C. Cartaro,}76_{F. Cossutti,}76 _{G. Della Ricca,}76 _{S. Dittongo,}76 _{S. Grancagnolo,}76 L. Lanceri,76 _{L. Vitale,}76 _{V. Azzolini,}77 _{F. Martinez-Vidal,}77 _{Sw. Banerjee,}78 _{B. Bhuyan,}78 _{C. M. Brown,}78 D. Fortin,78 _{K. Hamano,}78 _{R. Kowalewski,}78 _{I. M. Nugent,}78 _{J. M. Roney,}78 _{R. J. Sobie,}78 _{J. J. Back,}79 P. F. Harrison,79_{T. E. Latham,}79 _{G. B. Mohanty,}79 _{H. R. Band,}80 _{X. Chen,}80 _{B. Cheng,}80 _{S. Dasu,}80 _{M. Datta,}80 A. M. Eichenbaum,80 _{K. T. Flood,}80 _{J. J. Hollar,}80_{J. R. Johnson,}80_{P. E. Kutter,}80 _{H. Li,}80_{R. Liu,}80 _{B. Mellado,}80 A. Mihalyi,80_{A. K. Mohapatra,}80_{Y. Pan,}80_{M. Pierini,}80_{R. Prepost,}80 _{P. Tan,}80_{S. L. Wu,}80_{Z. Yu,}80_{and H. Neal}81

(The BA_BAR _{Collaboration)}

1_{Laboratoire de Physique des Particules, F-74941 Annecy-le-Vieux, France}

2_{Universitat de Barcelona Fac. Fisica. Dept. ECM Avda Diagonal 647, 6a planta E-08028 Barcelona, Spain} 3_{Universit`a di Bari, Dipartimento di Fisica and INFN, I-70126 Bari, Italy}

4_{Institute of High Energy Physics, Beijing 100039, China} 5_{University of Bergen, Institute of Physics, N-5007 Bergen, Norway}

6_{Lawrence Berkeley National Laboratory and University of California, Berkeley, California 94720, USA} 7_{University of Birmingham, Birmingham, B15 2TT, United Kingdom}

8_{Ruhr Universit¨at Bochum, Institut f¨ur Experimentalphysik 1, D-44780 Bochum, Germany} 9_{University of Bristol, Bristol BS8 1TL, United Kingdom}

10_{University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z1} 11_{Brunel University, Uxbridge, Middlesex UB8 3PH, United Kingdom}

12_{Budker Institute of Nuclear Physics, Novosibirsk 630090, Russia} 13_{University of California at Irvine, Irvine, California 92697, USA} 14_{University of California at Los Angeles, Los Angeles, California 90024, USA}

15_{University of California at Riverside, Riverside, California 92521, USA} 16_{University of California at San Diego, La Jolla, California 92093, USA} 17_{University of California at Santa Barbara, Santa Barbara, California 93106, USA}

19_{California Institute of Technology, Pasadena, California 91125, USA} 20_{University of Cincinnati, Cincinnati, Ohio 45221, USA} 21_{University of Colorado, Boulder, Colorado 80309, USA} 22_{Colorado State University, Fort Collins, Colorado 80523, USA} 23_{Universit¨at Dortmund, Institut f¨ur Physik, D-44221 Dortmund, Germany}

24_{Technische Universit¨at Dresden, Institut f¨ur Kern- und Teilchenphysik, D-01062 Dresden, Germany} 25_{Ecole Polytechnique, LLR, F-91128 Palaiseau, France}

26_{University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom}

27_{Universit`a di Ferrara, Dipartimento di Fisica and INFN, I-44100 Ferrara, Italy</sub> 28<sub>Laboratori Nazionali di Frascati dell’INFN, I-00044 Frascati, Italy</sub> 29<sub>Universit`a di Genova, Dipartimento di Fisica and INFN, I-16146 Genova, Italy}

30_{Harvard University, Cambridge, Massachusetts 02138, USA}

31_{Universit¨at Heidelberg, Physikalisches Institut, Philosophenweg 12, D-69120 Heidelberg, Germany} 32_{Imperial College London, London, SW7 2AZ, United Kingdom}

33_{University of Iowa, Iowa City, Iowa 52242, USA} 34_{Iowa State University, Ames, Iowa 50011-3160, USA}

35_{Johns Hopkins Univ. Dept of Physics & Astronomy 3400 N. Charles Street Baltimore, Maryland 21218} 36_{Universit¨at Karlsruhe, Institut f¨ur Experimentelle Kernphysik, D-76021 Karlsruhe, Germany}

37_{Laboratoire de l’Acc´el´erateur Lin´eaire, IN2P3-CNRS et Universit´e Paris-Sud 11,} Centre Scientifique d’Orsay, B.P. 34, F-91898 ORSAY Cedex, France 38_{Lawrence Livermore National Laboratory, Livermore, California 94550, USA}

39_{University of Liverpool, Liverpool L69 7ZE, United Kingdom} 40_{Queen Mary, University of London, E1 4NS, United Kingdom}

41_{University of London, Royal Holloway and Bedford New College, Egham, Surrey TW20 0EX, United Kingdom} 42_{University of Louisville, Louisville, Kentucky 40292, USA}

43_{University of Manchester, Manchester M13 9PL, United Kingdom} 44_{University of Maryland, College Park, Maryland 20742, USA} 45_{University of Massachusetts, Amherst, Massachusetts 01003, USA}

46_{Massachusetts Institute of Technology, Laboratory for Nuclear Science, Cambridge, Massachusetts 02139, USA} 47_{McGill University, Montr´eal, Qu´ebec, Canada H3A 2T8}

48_{Universit`a di Milano, Dipartimento di Fisica and INFN, I-20133 Milano, Italy} 49_{University of Mississippi, University, Mississippi 38677, USA}

50_{Universit´e de Montr´eal, Physique des Particules, Montr´eal, Qu´ebec, Canada H3C 3J7} 51_{Mount Holyoke College, South Hadley, Massachusetts 01075, USA}

52_{Universit`a di Napoli Federico II, Dipartimento di Scienze Fisiche and INFN, I-80126, Napoli, Italy}

53_{NIKHEF, National Institute for Nuclear Physics and High Energy Physics, NL-1009 DB Amsterdam, The Netherlands} 54_{University of Notre Dame, Notre Dame, Indiana 46556, USA}

55_{Ohio State University, Columbus, Ohio 43210, USA} 56_{University of Oregon, Eugene, Oregon 97403, USA}

57_{Universit`a di Padova, Dipartimento di Fisica and INFN, I-35131 Padova, Italy}

58_{Universit´es Paris VI et VII, Laboratoire de Physique Nucl´eaire et de Hautes Energies, F-75252 Paris, France} 59_{University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA}

60_{Universit`a di Perugia, Dipartimento di Fisica and INFN, I-06100 Perugia, Italy}

61_{Universit`a di Pisa, Dipartimento di Fisica, Scuola Normale Superiore and INFN, I-56127 Pisa, Italy} 62_{Prairie View A&M University, Prairie View, Texas 77446, USA}

63_{Princeton University, Princeton, New Jersey 08544, USA}

64_{Universit`a di Roma La Sapienza, Dipartimento di Fisica and INFN, I-00185 Roma, Italy} 65_{Universit¨at Rostock, D-18051 Rostock, Germany}

66_{Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, OX11 0QX, United Kingdom} 67_{DSM/Dapnia, CEA/Saclay, F-91191 Gif-sur-Yvette, France}

68_{University of South Carolina, Columbia, South Carolina 29208, USA} 69_{Stanford Linear Accelerator Center, Stanford, California 94309, USA}

70_{Stanford University, Stanford, California 94305-4060, USA} 71_{State University of New York, Albany, New York 12222, USA}

72_{University of Tennessee, Knoxville, Tennessee 37996, USA} 73_{University of Texas at Austin, Austin, Texas 78712, USA} 74_{University of Texas at Dallas, Richardson, Texas 75083, USA}

75_{Universit`a di Torino, Dipartimento di Fisica Sperimentale and INFN, I-10125 Torino, Italy</sub> 76<sub>Universit`a di Trieste, Dipartimento di Fisica and INFN, I-34127 Trieste, Italy}

77_{IFIC, Universitat de Valencia-CSIC, E-46071 Valencia, Spain} 78_{University of Victoria, Victoria, British Columbia, Canada V8W 3P6} 79_{Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom}

80_{University of Wisconsin, Madison, Wisconsin 53706, USA} 81_{Yale University, New Haven, Connecticut 06511, USA}

(Dated: October 29, 2018)

We search for the charmed pentaquark candidate reported by the H1 collaboration, the Θc(3100)0_, in e+_e−_{interactions at a center-of-mass (c.m.) energy of 10.58 GeV, using 124 fb}−1_{of data recorded} with the BABAR_{detector at the PEP-II e}+_e−_{facility at SLAC. We find no evidence for such a state} in the same pD∗− _{decay mode reported by H1, and we set limits on its production cross section} times branching fraction into pD∗− _{as a function of c.m. momentum. The corresponding limit on} its total rate per e+

e−

→ qq event, times branching fraction, is about three orders of magnitude lower than rates measured for the charmed Λc and Σc baryons in such events.

PACS numbers: 13.25.Hw, 12.15.Hh, 11.30.Er

Ten experimental groups have recently reported nar-row enhancements near 1540 MeV/c2 _{in the} invari-ant mass spectra for nK+ _{or pK}0

S [1]. The minimal

quark content of a state that decays strongly to nK+ is dduus; therefore, these mass peaks have been inter-preted as a possible pentaquark state, called Θ(1540)+_. The NA49 experiment has reported narrow enhance-ments near 1862 MeV/c2 _{in the invariant mass} spec-tra for Ξ−_π− _{and Ξ}−_π+ _{[2]; the former has minimal} quark content dssdu, and these two mass peaks have also been interpreted as possible pentaquark states, named Ξ(1860)−−_{and Ξ(1860)}0 _{[also known as Φ(1860)], with} the latter being a mixture of ussuu and ussdd. The H1 experiment has reported a narrow enhancement at a mass of 3099±6 MeV/c2 _{in the mass spectrum for pD}∗− _[3], which has a minimal quark content of uuddc, making this a possible charmed pentaquark state, named Θc(3100)0. On the other hand, there are numerous experimental searches with negative results [4]: several experiments observe large samples of strange baryons with mass sim-ilar to that of the Θ(1540)+_{, e.g. Λ(1520)→pK}−_{, but no} evidence for the Θ(1540)+_{; several observe large samples} of the nonexotic Ξ− _{baryon, but not the Ξ(1860)}−−_or Ξ(1860)0 _{states; and several with large samples of D}∗− do not observe the Θc(3100)0state. Our recent search [5] for the Θ(1540)+ _{and Ξ(1860)}−−_{in e}+_e− _{annihilations} found no evidence for these states, and we set limits on their production rates in e+_e− _{→ qq events of factors} of eight and four, respectively, below rates expected for ordinary baryons of the same masses.

Here we report the results of an inclusive search for the charmed pentaquark candidate Θc(3100)0in e+e− anni-hilation data; we expect equal production of the charge conjugate state, and its inclusion is implied throughout this article. The data were recorded with the BA_BAR

de-tector [6] at the PEP-II asymmetric-energy e+_e−_storage rings located at the Stanford Linear Accelerator Center. The data sample represents an integrated luminosity of 124 fb−1 collected at an e+_e− _{c.m. energy at or just}

be-∗_{Also at Laboratoire de Physique Corpusculaire,} Clermont-Ferrand, France

†_{Also with Universit`a di Perugia, Dipartimento di Fisica, Perugia,} Italy

‡_{Also with Universit`a della Basilicata, Potenza, Italy}

low the mass of the Υ (4S) resonance. We study the same decay mode as in the H1 analysis, Θc(3100)0 → pD∗−, where the D∗− _{decays to D}0_π−

s (π−s denotes a “slow” pion from the D∗− _{decay), and the D}0_{decays to K}+_π−_. In addition, we consider the mode in which the D0decays to K+π−_π+_π−_.

The BA_BAR _{detector is described in detail in Ref. 6.}

We use all events accepted by our trigger, which is more than 99% efficient for both e+_e−_{→ qq and e}+_e−_{→ Υ (4S)} events. We use charged tracks reconstructed in the five-layer silicon vertex tracker (SVT) and the 40-five-layer drift chamber (DCH). The combined momentum resolution, σ(pT), is given by [σ(pT)/pT]2 = [0.0013pT]2+ 0.00452, where pT is the momentum transverse to the beam axis measured in GeV/c. Particles are identified as pions, kaons, or protons with a combination of the energy-loss measured in the two tracking detectors and the Cherenkov angles measured in the detector of internally reflected Cherenkov radiation (DIRC).

We evaluate the Θc(3100)0 reconstruction efficiency and invariant mass resolution from two simulations. For production in e+_e−

→ cc events, we use the JETSET [7] Monte Carlo generator with the mass and width of the Σc(2455)0 baryon set to 3099 MeV/c2 and 1 MeV, re-spectively, and allow only the pD∗− _{decay mode. We} leave all other parameters unchanged, and a momentum spectrum similar to those of nonexotic charmed baryons is produced. The events have a total charm of ±2, but this has negligible effect on the number and distribution of additional particles in the event, which are the quan-tities of interest here. We also simulate Υ (4S) decays in which one B decays generically in our standard frame-work [8] and the other decays into a state containing a Σc(2455)0 with parameters adjusted in the same way. This gives a much softer momentum spectrum, cut off at the kinematic limit for B meson decays, and a differ-ent environmdiffer-ent in terms of other particles in the evdiffer-ent. We find that the efficiency and resolution depend primar-ily on the Θc(3100)0 momentum and polar angle in the laboratory frame, and negligibly on other aspects of the production process or event environment. We use large control samples of particles identified in the data to cor-rect small inaccuracies in the performance predicted by the GEANT-based [9] detector simulation.

We choose Θc(3100)0 candidate selection criteria de-signed for high efficiency and low bias against any

pro-D0→ K+π− 140 145 150 155 ∆m (MeV/c2) 0 4 8 12 Candidates / (0.2 MeV/c 2) D0→ K+π−π+π− x103

-FIG. 1: a) Distributions of the invariant mass difference be-tween the D∗− _{and D}0

combinations in X → pD∗− candi-dates in the data, for the two D0 decay modes. b) Distribu-tion of the reconstructed momentum of the D∗− _{in the e}+

e− c.m. frame for pD∗− _{candidates in the data (histogram); the} dashed (dotted) line represents the D∗− _{spectra measured in} Υ (4S) decays (e+

e−

→ cc events) scaled as described in the text.

duction mechanism. We use charged tracks reconstructed with at least twelve coordinates measured in the DCH, and select identified pions, kaons and protons. The iden-tification criteria for pions and kaons are fairly loose, having efficiencies better than 99% and misidentifica-tion rates below 1% for momenta below 0.5 GeV/c where energy loss in the SVT and DCH provide good separa-tion, and efficiencies of roughly 80% and misidentification rates below 10% for momenta above 0.8 GeV/c where the Cherenkov angles are measured well in the DIRC. The criteria for identified protons are tighter. For momenta below 1 GeV/c and above 1.5 GeV/c the efficiencies are better than 95% and 75%, and the misidentification rates are below 1% and 3%, respectively.

In each event we consider every combination of identi-fied pK+_π−_π−_{and pK}+_π−_π+_π−_π−_{and perform a} topo-logical fit to each combination with the hypothesized de-cay chain X→ pD∗−

→ pD0π−

s→ pK+π−(π+π−)π−s. No mass constraints are used in the fit, but the decay prod-ucts at each stage are required to originate at a single space point. The D0 has a finite flight distance, and we require the confidence level of the χ2_{for its decay vertex} to exceed 10−4.

We select candidates in which both the reconstructed D0 and D∗− _{masses are within 20 MeV/c}2 _{of the peak} value, namely 1843.8 < mK+_π−_(π+_π−₎< 1883.8 MeV/c2

and 1989 < m_K+_π−_(π+_π−_)π−

s < 2029 MeV/c

2_{. In Fig. 1a} we show the distributions of the differences in recon-structed invariant mass ∆m = m_K+_π−π−_s − mK+_π− and

m_K+_π−_π+_π−_πs−− mK+_π−π+_π− for these X → pK+π−π−_s

and pK+_π−_π+_π−_π−

s candidates, respectively. Clear sig-nals for D∗−_{are visible in both cases, with peak positions} and widths (∼0.6 MeV/c2_{) consistent with expectations} from our simulation. The widths (∼6 MeV/c2_{) of the} corresponding D0and D∗−_{peaks (not shown) are} under-estimated by about 10% in the simulation. We require a mass difference within 2 MeV/c2 _{of the peak value,}

143.48< ∆m <147.48 MeV/c2_. About 55,000 D∗− _{→ K}+_π−_π−

s decays and 73,000 D∗−_→K+_π−_π−_π+_π−

s decays are present in the selected data over respective backgrounds of 4,000 and 62,000 random combinations. No event in either the data or simulation has more than one surviving pD∗− _candidate. Without the proton requirement, over 750,000 D∗− _are seen. Figure 1b shows the distribution of the D∗− mo-mentum, p∗_{, in the c.m. frame for the selected data. A} characteristic two-peak structure is evident, in which the peak at lower p∗ _{values is due to D}∗− _{from decays of B} hadrons from Υ (4S) decays, and the peak at higher p∗ values is due to e+_e−_{→ cc events. For purposes of} il-lustration, we show the spectra measured [10] from these two sources on Fig. 1b, scaled by our integrated lumi-nosity, average efficiency and fraction of events with a proton. The shape is modified by the selection criteria; in particular, the proton requirement shifts the edge at the highest p∗_{values. The background is verified by} side-band studies to be concentrated at lower p∗ _{values; it is} clear that we are sensitive to Θc(3100)0production from both of these sources.

We evaluate the Θc(3100)0reconstruction efficiency for each search mode from the simulation, as a function of p∗_{. High-mass particles at low p}∗ _{are boosted forward} in our laboratory frame, so that the probability of losing at least one track outside the acceptance is large, and the efficiencies are low, about 10% and 5% for the K+_π− and K+_π−_π+_π− _{modes, respectively. The efficiencies} rise with increasing p∗ _{to respective maximum values of} 30% and 22% at the kinematic limit. The invariant mass requirements introduce negligible signal loss. The rela-tive systematic uncertainties on the tracking and particle identification efficiencies total 6–8%; at low and high p∗ values, there is a contribution of similar size from the statistics of the simulation.

We calculate the Θc(3100)0 candidate invariant mass as mpD∗≡ m_pK+_π−_(π+_π−_)π−

s− mK+π−(π+π−)π−s+ mD∗−,

where mD∗−= 2010 MeV/c2 is the known D∗− mass [11].

We take the resolution on this quantity from the simula-tion, as it is insensitive to the simulated D(∗) _mass res-olution and previous studies involving protons combined with K0

S [5] showed the proton contribution to be well

simulated. We describe the resolution by a sum of two Gaussian functions with a common center. The width of the core (tail) Gaussian averages 2.5 (20) MeV/c2_, al-most independent of p∗_{, and the wider Gaussian} con-tributes between 20% of the total at low p∗ _{and 10% at} high p∗_{. The overall resolution, defined as the FWHM} of the resolution function divided by 2.355, averages 2.8 and 3.0 MeV/c2 _{for the K}+_π− _{and K}+_π−_π+_π− _decay modes, respectively, with a small dependence on p∗_.

We show mpD∗ distributions for the Θc(3100)0 candi-dates in the data in Fig. 2 for the two D0 decay modes. They show no narrow structure; in particular they are smooth in the region near 3100 MeV/c2_{, shown in the} inset, where the bin size is two-thirds of the resolution.

3.060 3.080 3.100 3.120 3.140 0 100 200 300 Cands. / (2 MeV/c 2) 3.0 3.5 4.0 4.5 5.0 pD∗− Mass (GeV/c2) 0 500 1000 1500 Candidates / (10 MeV/c 2) _D0_{→ K}+_π−_π+_π− D0→ K+π−

-FIG. 2: Invariant mass distributions for Θc(3100)0 candi-dates in the data in the (black) K+

π−_{and (gray) K}+

π−_π−_π+ decay modes, over a wide mass range and (inset) in the region near 3100 MeV/c2_.

Corresponding distributions for sidebands in the D0 and D∗− _{masses and the mass differences show overall} struc-ture similar to that in the signal region. We consider several variations of the selection criteria that might en-hance a pentaquark signal, but in no case do we observe one. To enhance our sensitivity to any production mech-anism that gives a p∗_{spectrum different from that of the} background, we divide the data into nine p∗ _{ranges of} width 500 MeV/c covering values from 0 to 4.5 GeV/c. The background is lower at high p∗_{, so we are more} sen-sitive to mechanisms that produce harder spectra. There is no evidence of a pentaquark signal in any p∗ _range.

We quantify this null result by fitting a signal-plus-background function to the mpD∗ distribution in each

p∗ _{range. We use a p-wave Breit-Wigner lineshape} convolved with the resolution function described above. The RMS width of the reported Θc(3100)0 signal is 12 MeV/c2 _{and consistent with the H1 detector} reso-lution [3]. Our mass resoreso-lution is considerably better, so we must consider a range of possible natural widths Γ of the Θc(3100)0. We quote results for two assumed widths, Γ = 1 MeV, corresponding to a very narrow state, and Γ = 28 MeV, corresponding to the width ob-served by H1, which we take as an upper limit. For the background we use the function f (m) = 0 for m < m0 and f (m) =p1 − (m0/m)2exp(a[1 − (m0/m)2])/m for m > m0, where m0= mp+ mD∗−= 2948 MeV/c2 is the

threshold value and a is a free parameter. We fit over the range from threshold to 3300 MeV/c2_{, except in the} lowest p∗ _{range for the K}+_π−_π+_π− _{mode. Here the} ac-ceptance drops sharply near threshold and the fit range is restricted to the region above 3000 MeV/c2_.

We perform maximum likelihood fits at several fixed Θc(3100)0 mass values in the range 3087–3111 MeV/c2. In every case we find good fit quality and a signal ampli-tude consistent with zero. We consider systematic effects in the fitting procedure by varying the signal and

back-0 1 2 3 4 p* (GeV/c) -100 -50 0 50 100 150

Fitted Signal Yield

Γ = 1 MeV Γ = 28 MeV 0 1 2 3 4 p* (GeV/c) D

-

-

yields from fits to the mpD∗ distributions

for the (left) pK+_π−_π−

s and (right) pK

+_π−_π+_π−_π− s decay modes, assuming a mass of 3099 MeV/c2_{and a natural width} of Γ = 1 MeV (black) or Γ =28 MeV (gray).

ground functions and fit range; changes in the signal yield are negligible compared with the statistical uncertainties. The dependence on the assumed mass value is also small compared with the statistical error in each case. Fix-ing the mass to the reported value of 3099 MeV/c2_{, we} obtain the event yields shown in Fig. 3. There is no pos-itive trend in the data, and the roughly symmetric scat-ter of the points about zero indicates little momentum-dependent bias in the background function.

In each p∗ _{range we divide the sum of the two signal} yields by the sum of the two products of reconstruction efficiency and D0→ K+_π− _{or D}0_{→ K}+_π−_π+_π− branch-ing fraction, the D∗−

→ D0π−

s branching fraction, the integrated luminosity, and the p∗ _{range. This gives the} product of the unknown Θc(3100)0→ pD∗− branching fraction, B, and the differential production cross section, dσ/dp∗_{. The resulting values of B·dσ/dp}∗_{for Γ =1 MeV} and Γ =28 MeV are shown in Fig. 4. We derive an upper limit on the value in each p∗_{range under the assumption} that it cannot be negative: a Gaussian function centered at the measured value with RMS equal to the total un-certainty is integrated from zero to infinity, and the point at which the integral reaches 95% of this total is taken as the limit. These 95% confidence level (CL) upper limits are also shown in Fig. 4.

We integrate B · dσ/dp∗ _{over the full p}∗ _{range from} 0–4.5 GeV/c, taking into account the correlation in the systematic uncertainty, to derive a total production cross section times branching fraction, B·σ, for each of the two assumed Γ values, and calculate corresponding upper lim-its. These limits are model independent; any postulated production spectrum can be folded with the measured differential cross section to obtain a smaller limit. We cal-culate corresponding limits on the number of Θc(3100)0 produced per qq (q = udsc) event and per cc event by dividing by the respective cross sections for these types of events; we also calculate a limit per Υ (4S) decay by integrating B·dσ/dp∗ _{over the range p}∗_{< 2 GeV/c (the} kinematic limit for B meson decays is 1.8 GeV/c) and dividing by our effective cross section for e+_e−

→ Υ (4S). These central values and limits are given in Table I.

-100 0 100 200 300 400 500 600 B × d σ /dp* fb / (GeV/c) Γ = 1 MeV Γ = 28 MeV 0 1 2 3 4 p* (GeV/c) UL: Γ = 1 MeV UL: Γ = 28 MeV

FIG. 4: Product of the Θc(3100)0

differential production cross section and its branching fraction to pD∗− _(symbols) and corresponding 95% CL upper limits (lines), assuming natural widths of Γ = 1 MeV (solid) and Γ = 28 MeV (open/dashed), as functions of c.m. momentum.

TABLE I: Total production cross section of the Θc(3100)0 pentaquark candidate times its branching fraction to pD∗−_, B·σ, in e+_e−_{annihilations at}√_{s =10.58 GeV, for two assumed} values of the natural width. The corresponding 95% CL upper limits on B·σ and on B times the yields per e+

e−

→ qq event, e+_e−

→ cc event, and Υ (4S) decay.

Γ = 1 MeV Γ = 28 MeV B·σ (fb) 40±44 102±111 < 117 < 297 B×yield×10−5 per e+_e− → qq event < 3.4 < 8.8 e+_e− → cc event < 8.5 < 22 Υ (4S) decay < 12 < 37

In summary, we perform a search in e+_e− annihila-tions at √s =10.58 GeV for the pentaquark candidate state Θc(3100)0 reported by the H1 collaboration. We

use the same decay mode as H1, Θc(3100)0→pD∗−, and find no evidence for the production of this state in a sample of over 125,000 pD∗− _{combinations. The} com-ponents of this sample from c-quark fragmentation and B0_/B0_{+ B}± _{decays are both at least 100 times larger} than the sample used by H1, implying that neither hard charm quarks nor B mesons produced in deep inelastic scattering can be the source of the H1 signal. We set upper limits on the product of the inclusive Θc(3100)0 production cross section times branching fraction to this mode for two assumptions as to its natural width, which are valid for any state in the vicinity of 3100 MeV/c2_. It would be interesting to compare these limits with the rate expected for an ordinary charmed baryon of mass ∼3100 MeV/c2. However rates have been measured for only two charmed baryons, the Λ+

c(2285) [10, 11] and Σc(2455) [11], with precision that does not allow a mean-ingful estimate of the mass dependence. The mass depen-dence observed [11] for non-charmed baryons in e+_e− an-nihilations would predict a rate for a 3100 MeV/c2_baryon about 1,000 times smaller than that of the Λ+

c(2285). Our limits for a narrow state in both e+_e− _{→ cc and} Υ (4S) events are roughly 1,000 and 500 times below the measured Λ+

c(2285) and Σc(2455) rates, respectively. As a result the existence of an ordinary charmed baryon with this mass and decay mode cannot be excluded.

We are grateful for the excellent luminosity and ma-chine conditions provided by our PEP-II colleagues, and for the substantial dedicated effort from the computing organizations that support BA_BAR_{. The collaborating}

institutions wish to thank SLAC for its support and kind hospitality. This work is supported by DOE and NSF (USA), NSERC (Canada), IHEP (China), CEA and CNRS-IN2P3 (France), BMBF and DFG (Germany), INFN (Italy), FOM (The Netherlands), NFR (Norway), MIST (Russia), and PPARC (United Kingdom). Indi-viduals have received support from CONACyT (Mex-ico), Marie Curie EIF (European Union), the A. P. Sloan Foundation, the Research Corporation, and the Alexan-der von Humboldt Foundation.

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