of 8
Observation of
B
0
!

c
0
K

0
and evidence for
B
þ
!

c
0
K
B. Aubert,
1
M. Bona,
1
Y. Karyotakis,
1
J. P. Lees,
1
V. Poireau,
1
E. Prencipe,
1
X. Prudent,
1
V. Tisserand,
1
J. Garra Tico,
2
E. Grauges,
2
L. Lopez,
3a,3b
A. Palano,
3a,3b
M. Pappagallo,
3a,3b
G. Eigen,
4
B. Stugu,
4
L. Sun,
4
G. S. Abrams,
5
M. Battaglia,
5
D. N. Brown,
5
R. N. Cahn,
5
R. G. Jacobsen,
5
L. T. Kerth,
5
Yu. G. Kolomensky,
5
G. Lynch,
5
I. L. Osipenkov,
5
M. T. Ronan,
5,
*
K. Tackmann,
5
T. Tanabe,
5
C. M. Hawkes,
6
N. Soni,
6
A. T. Watson,
6
H. Koch,
7
T. Schroeder,
7
D. Walker,
8
D. J. Asgeirsson,
9
B. G. Fulsom,
9
C. Hearty,
9
T. S. Mattison,
9
J. A. McKenna,
9
M. Barrett,
10
A. Khan,
10
V. E. Blinov,
11
A. D. Bukin,
11
A. R. Buzykaev,
11
V. P. Druzhinin,
11
V. B. Golubev,
11
A. P. Onuchin,
11
S. I. Serednyakov,
11
Yu. I. Skovpen,
11
E. P. Solodov,
11
K. Yu. Todyshev,
11
M. Bondioli,
12
S. Curry,
12
I. Eschrich,
12
D. Kirkby,
12
A. J. Lankford,
12
P. Lund,
12
M. Mandelkern,
12
E. C. Martin,
12
D. P. Stoker,
12
S. Abachi,
13
C. Buchanan,
13
J. W. Gary,
14
F. Liu,
14
O. Long,
14
B. C. Shen,
14,
*
G. M. Vitug,
14
Z. Yasin,
14
L. Zhang,
14
V. Sharma,
15
C. Campagnari,
16
T. M. Hong,
16
D. Kovalskyi,
16
M. A. Mazur,
16
J. D. Richman,
16
T. W. Beck,
17
A. M. Eisner,
17
C. J. Flacco,
17
C. A. Heusch,
17
J. Kroseberg,
17
W. S. Lockman,
17
A. J. Martinez,
17
T. Schalk,
17
B. A. Schumm,
17
A. Seiden,
17
M. G. Wilson,
17
L. O. Winstrom,
17
C. H. Cheng,
18
D. A. Doll,
18
B. Echenard,
18
F. Fang,
18
D. G. Hitlin,
18
I. Narsky,
18
T. Piatenko,
18
F. C. Porter,
18
R. Andreassen,
19
G. Mancinelli,
19
B. T. Meadows,
19
K. Mishra,
19
M. D. Sokoloff,
19
P. C. Bloom,
20
W. T. Ford,
20
A. Gaz,
20
J. F. Hirschauer,
20
M. Nagel,
20
U. Nauenberg,
20
J. G. Smith,
20
K. A. Ulmer,
20
S. R. Wagner,
20
R. Ayad,
21,
+
A. Soffer,
21,
W. H. Toki,
21
R. J. Wilson,
21
D. D. Altenburg,
22
E. Feltresi,
22
A. Hauke,
22
H. Jasper,
22
M. Karbach,
22
J. Merkel,
22
A. Petzold,
22
B. Spaan,
22
K. Wacker,
22
M. J. Kobel,
23
W. F. Mader,
23
R. Nogowski,
23
K. R. Schubert,
23
R. Schwierz,
23
A. Volk,
23
D. Bernard,
24
G. R. Bonneaud,
24
E. Latour,
24
M. Verderi,
24
P. J. Clark,
25
S. Playfer,
25
J. E. Watson,
25
M. Andreotti,
26a,26b
D. Bettoni,
26a
C. Bozzi,
26a
R. Calabrese,
26a,26b
A. Cecchi,
26a,26b
G. Cibinetto,
26a,26b
P. Franchini,
26a,26b
E. Luppi,
26a,26b
M. Negrini,
26a,26b
A. Petrella,
26a,26b
L. Piemontese,
26a
V. Santoro,
26a,26b
R. Baldini-Ferroli,
27
A. Calcaterra,
27
R. de Sangro,
27
G. Finocchiaro,
27
S. Pacetti,
27
P. Patteri,
27
I. M. Peruzzi,
27,
x
M. Piccolo,
27
M. Rama,
27
A. Zallo,
27
A. Buzzo,
28a
R. Contri,
28a,28b
M. Lo Vetere,
28a,28b
M. M. Macri,
28a
M. R. Monge,
28a,28b
S. Passaggio,
28a
C. Patrignani,
28a,28b
E. Robutti,
28a
A. Santroni,
28a,28b
S. Tosi,
28a,28b
K. S. Chaisanguanthum,
29
M. Morii,
29
A. Adametz,
30
J. Marks,
30
S. Schenk,
30
U. Uwer,
30
V. Klose,
31
H. M. Lacker,
31
D. J. Bard,
32
P. D. Dauncey,
32
J. A. Nash,
32
M. Tibbetts,
32
P. K. Behera,
33
X. Chai,
33
M. J. Charles,
33
U. Mallik,
33
J. Cochran,
34
H. B. Crawley,
34
L. Dong,
34
W. T. Meyer,
34
S. Prell,
34
E. I. Rosenberg,
34
A. E. Rubin,
34
Y. Y. Gao,
35
A. V. Gritsan,
35
Z. J. Guo,
35
C. K. Lae,
35
N. Arnaud,
36
J. Be
́
quilleux,
36
A. D’Orazio,
36
M. Davier,
36
J. Firmino da Costa,
36
G. Grosdidier,
36
A. Ho
̈
cker,
36
V. Lepeltier,
36
F. Le Diberder,
36
A. M. Lutz,
36
S. Pruvot,
36
P. Roudeau,
36
M. H. Schune,
36
J. Serrano,
36
V. Sordini,
36,
k
A. Stocchi,
36
G. Wormser,
36
D. J. Lange,
37
D. M. Wright,
37
I. Bingham,
38
J. P. Burke,
38
C. A. Chavez,
38
J. R. Fry,
38
E. Gabathuler,
38
R. Gamet,
38
D. E. Hutchcroft,
38
D. J. Payne,
38
C. Touramanis,
38
A. J. Bevan,
39
C. K. Clarke,
39
K. A. George,
39
F. Di Lodovico,
39
R. Sacco,
39
M. Sigamani,
39
G. Cowan,
40
H. U. Flaecher,
40
D. A. Hopkins,
40
S. Paramesvaran,
40
F. Salvatore,
40
A. C. Wren,
40
D. N. Brown,
41
C. L. Davis,
41
A. G. Denig,
42
M. Fritsch,
42
W. Gradl,
42
G. Schott,
42
K. E. Alwyn,
43
D. Bailey,
43
R. J. Barlow,
43
Y. M. Chia,
43
C. L. Edgar,
43
G. Jackson,
43
G. D. Lafferty,
43
T. J. West,
43
J. I. Yi,
43
J. Anderson,
44
C. Chen,
44
A. Jawahery,
44
D. A. Roberts,
44
G. Simi,
44
J. M. Tuggle,
44
C. Dallapiccola,
45
X. Li,
45
E. Salvati,
45
S. Saremi,
45
R. Cowan,
46
D. Dujmic,
46
P. H. Fisher,
46
G. Sciolla,
46
M. Spitznagel,
46
F. Taylor,
46
R. K. Yamamoto,
46
M. Zhao,
46
P. M. Patel,
47
S. H. Robertson,
47
A. Lazzaro,
48a,48b
V. Lombardo,
48a
F. Palombo,
48a,48b
J. M. Bauer,
49
L. Cremaldi,
49
R. Godang,
49,
{
R. Kroeger,
49
D. A. Sanders,
49
D. J. Summers,
49
H. W. Zhao,
49
M. Simard,
50
P. Taras,
50
F. B. Viaud,
50
H. Nicholson,
51
G. De Nardo,
52a,52b
L. Lista,
52a
D. Monorchio,
52a,52b
G. Onorato,
52a,52b
C. Sciacca,
52a,52b
G. Raven,
53
H. L. Snoek,
53
C. P. Jessop,
54
K. J. Knoepfel,
54
J. M. LoSecco,
54
W. F. Wang,
54
G. Benelli,
55
L. A. Corwin,
55
K. Honscheid,
55
H. Kagan,
55
R. Kass,
55
J. P. Morris,
55
A. M. Rahimi,
55
J. J. Regensburger,
55
S. J. Sekula,
55
Q. K. Wong,
55
N. L. Blount,
56
J. Brau,
56
R. Frey,
56
O. Igonkina,
56
J. A. Kolb,
56
M. Lu,
56
R. Rahmat,
56
N. B. Sinev,
56
D. Strom,
56
J. Strube,
56
E. Torrence,
56
G. Castelli,
57a,57b
N. Gagliardi,
57a,57b
M. Margoni,
57a,57b
M. Morandin,
57a
M. Posocco,
57a
M. Rotondo,
57a
F. Simonetto,
57a,57b
R. Stroili,
57a,57b
C. Voci,
57a,57b
P. del Amo Sanchez,
58
E. Ben-Haim,
58
H. Briand,
58
G. Calderini,
58
J. Chauveau,
58
P. David,
58
L. Del Buono,
58
O. Hamon,
58
Ph. Leruste,
58
J. Ocariz,
58
A. Perez,
58
J. Prendki,
58
S. Sitt,
58
L. Gladney,
59
M. Biasini,
60a,60b
R. Covarelli,
60a,60b
E. Manoni,
60a,60b
C. Angelini,
61a,61b
G. Batignani,
61a,61b
S. Bettarini,
61a,61b
M. Carpinelli,
61a,61b,
**
A. Cervelli,
61a,61b
F. Forti,
61a,61b
M. A. Giorgi,
61a,61b
A. Lusiani,
61a,61c
G. Marchiori,
61a,61b
M. Morganti,
61a,61b
N. Neri,
61a,61b
E. Paoloni,
61a,61b
G. Rizzo,
61a,61b
J. J. Walsh,
61a
D. Lopes Pegna,
62
C. Lu,
62
J. Olsen,
62
A. J. S. Smith,
62
A. V. Telnov,
62
F. Anulli,
63a
E. Baracchini,
63a,63b
G. Cavoto,
63a
D. del Re,
63a,63b
E. Di Marco,
63a,63b
R. Faccini,
63a,63b
F. Ferrarotto,
63a
F. Ferroni,
63a,63b
M. Gaspero,
63a,63b
P. D. Jackson,
63a
L. Li Gioi,
63a
M. A. Mazzoni,
63a
S. Morganti,
63a
PHYSICAL REVIEW D
78,
091101(R) (2008)
RAPID COMMUNICATIONS
1550-7998
=
2008
=
78(9)
=
091101(8)
091101-1
Ó
2008 The American Physical Society
G. Piredda,
63a
F. Polci,
63a,63b
F. Renga,
63a,63b
C. Voena,
63a
M. Ebert,
64
T. Hartmann,
64
H. Schro
̈
der,
64
R. Waldi,
64
T. Adye,
65
B. Franek,
65
E. O. Olaiya,
65
F. F. Wilson,
65
S. Emery,
66
M. Escalier,
66
L. Esteve,
66
S. F. Ganzhur,
66
G. Hamel de Monchenault,
66
W. Kozanecki,
66
G. Vasseur,
66
Ch. Ye
`
che,
66
M. Zito,
66
X. R. Chen,
67
H. Liu,
67
W. Park,
67
M. V. Purohit,
67
R. M. White,
67
J. R. Wilson,
67
M. T. Allen,
68
D. Aston,
68
R. Bartoldus,
68
P. Bechtle,
68
J. F. Benitez,
68
R. Cenci,
68
J. P. Coleman,
68
M. R. Convery,
68
J. C. Dingfelder,
68
J. Dorfan,
68
G. P. Dubois-Felsmann,
68
W. Dunwoodie,
68
R. C. Field,
68
A. M. Gabareen,
68
S. J. Gowdy,
68
M. T. Graham,
68
P. Grenier,
68
C. Hast,
68
W. R. Innes,
68
J. Kaminski,
68
M. H. Kelsey,
68
H. Kim,
68
P. Kim,
68
M. L. Kocian,
68
D. W. G. S. Leith,
68
S. Li,
68
B. Lindquist,
68
S. Luitz,
68
V. Luth,
68
H. L. Lynch,
68
D. B. MacFarlane,
68
H. Marsiske,
68
R. Messner,
68
D. R. Muller,
68
H. Neal,
68
S. Nelson,
68
C. P. O’Grady,
68
I. Ofte,
68
A. Perazzo,
68
M. Perl,
68
B. N. Ratcliff,
68
A. Roodman,
68
A. A. Salnikov,
68
R. H. Schindler,
68
J. Schwiening,
68
A. Snyder,
68
D. Su,
68
M. K. Sullivan,
68
K. Suzuki,
68
S. K. Swain,
68
J. M. Thompson,
68
J. Va’vra,
68
A. P. Wagner,
68
M. Weaver,
68
C. A. West,
68
W. J. Wisniewski,
68
M. Wittgen,
68
D. H. Wright,
68
H. W. Wulsin,
68
A. K. Yarritu,
68
K. Yi,
68
C. C. Young,
68
V. Ziegler,
68
P. R. Burchat,
69
A. J. Edwards,
69
S. A. Majewski,
69
T. S. Miyashita,
69
B. A. Petersen,
69
L. Wilden,
69
S. Ahmed,
70
M. S. Alam,
70
J. A. Ernst,
70
B. Pan,
70
M. A. Saeed,
70
S. B. Zain,
70
S. M. Spanier,
71
B. J. Wogsland,
71
R. Eckmann,
72
J. L. Ritchie,
72
A. M. Ruland,
72
C. J. Schilling,
72
R. F. Schwitters,
72
B. W. Drummond,
73
J. M. Izen,
73
X. C. Lou,
73
F. Bianchi,
74a,74b
D. Gamba,
74a,74b
M. Pelliccioni,
74a,74b
M. Bomben,
75a,75b
L. Bosisio,
75a,75b
C. Cartaro,
75a,75b
G. Della Ricca,
75a,75b
L. Lanceri,
75a,75b
L. Vitale,
75a,75b
V. Azzolini,
76
N. Lopez-March,
76
F. Martinez-Vidal,
76
D. A. Milanes,
76
A. Oyanguren,
76
J. Albert,
77
Sw. Banerjee,
77
B. Bhuyan,
77
H. H. F. Choi,
77
K. Hamano,
77
R. Kowalewski,
77
M. J. Lewczuk,
77
I. M. Nugent,
77
J. M. Roney,
77
R. J. Sobie,
77
T. J. Gershon,
78
P. F. Harrison,
78
J. Ilic,
78
T. E. Latham,
78
G. B. Mohanty,
78
H. R. Band,
79
X. Chen,
79
S. Dasu,
79
K. T. Flood,
79
Y. Pan,
79
M. Pierini,
79
R. Prepost,
79
C. O. Vuosalo,
79
and S. L. Wu
79
(The
B
A
B
AR
Collaboration)
1
Laboratoire de Physique des Particules, IN2P3/CNRS et Universite
́
de Savoie, F-74941 Annecy-Le-Vieux, France
2
Universitat de Barcelona, Facultat de Fisica, Departament ECM, E-08028 Barcelona, Spain
3a
INFN Sezione di Bari, I-70126 Bari, Italy
3b
Dipartmento di Fisica, Universita
`
di Bari, I-70126 Bari, Italy
4
University of Bergen, Institute of Physics, N-5007 Bergen, Norway
5
Lawrence Berkeley National Laboratory and University of California, Berkeley, California 94720, USA
6
University of Birmingham, Birmingham, B15 2TT, United Kingdom
7
Ruhr Universita
̈
t Bochum, Institut fu
̈
r Experimentalphysik 1, D-44780 Bochum, Germany
8
University of Bristol, Bristol BS8 1TL, United Kingdom
9
University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z1
10
Brunel University, Uxbridge, Middlesex UB8 3PH, United Kingdom
11
Budker Institute of Nuclear Physics, Novosibirsk 630090, Russia
12
University of California at Irvine, Irvine, California 92697, USA
13
University of California at Los Angeles, Los Angeles, California 90024, USA
14
University of California at Riverside, Riverside, California 92521, USA
15
University of California at San Diego, La Jolla, California 92093, USA
16
University of California at Santa Barbara, Santa Barbara, California 93106, USA
17
University of California at Santa Cruz, Institute for Particle Physics, Santa Cruz, California 95064, USA
18
California Institute of Technology, Pasadena, California 91125, USA
19
University of Cincinnati, Cincinnati, Ohio 45221, USA
20
University of Colorado, Boulder, Colorado 80309, USA
21
Colorado State University, Fort Collins, Colorado 80523, USA
22
Technische Universita
̈
t Dortmund, Fakulta
̈
t Physik, D-44221 Dortmund, Germany
23
Technische Universita
̈
t Dresden, Institut fu
̈
r Kern- und Teilchenphysik, D-01062 Dresden, Germany
24
Laboratoire Leprince-Ringuet, CNRS/IN2P3, Ecole Polytechnique, F-91128 Palaiseau, France
25
University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom
26a
INFN Sezione di Ferrara, I-44100 Ferrara, Italy
26b
Dipartimento di Fisica, Universita
`
di Ferrara, I-44100 Ferrara, Italy
27
INFN Laboratori Nazionali di Frascati, I-00044 Frascati, Italy
28a
INFN Sezione di Genova, I-16146 Genova, Italy
28b
Dipartimento di Fisica, Universita
`
di Genova, I-16146 Genova, Italy
29
Harvard University, Cambridge, Massachusetts 02138, USA
30
Universita
̈
t Heidelberg, Physikalisches Institut, Philosophenweg 12, D-69120 Heidelberg, Germany
B. AUBERT
et al.
PHYSICAL REVIEW D
78,
091101(R) (2008)
RAPID COMMUNICATIONS
091101-2
31
Humboldt-Universita
̈
t zu Berlin, Institut fu
̈
r Physik, Newtonstr. 15, D-12489 Berlin, 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 University, Baltimore, Maryland 21218, USA
36
Laboratoire de l’Acce
́
le
́
rateur Line
́
aire, IN2P3/CNRS et Universite
́
Paris-Sud 11, Centre Scientifique d’Orsay,
B. P. 34, F-91898 Orsay Cedex, France
37
Lawrence Livermore National Laboratory, Livermore, California 94550, USA
38
University of Liverpool, Liverpool L69 7ZE, United Kingdom
39
Queen Mary, University of London, London, E1 4NS, United Kingdom
40
University of London, Royal Holloway and Bedford New College, Egham, Surrey TW20 0EX, United Kingdom
41
University of Louisville, Louisville, Kentucky 40292, USA
42
Johannes Gutenberg-Universita
̈
t Mainz, Institut fu
̈
r Kernphysik, D-55099 Mainz, Germany
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, Montre
́
al, Que
́
bec, Canada H3A 2T8
48a
INFN Sezione di Milano, I-20133 Milano, Italy
48b
Dipartimento di Fisica, Universita
`
di Milano, I-20133 Milano, Italy
49
University of Mississippi, University, Mississippi 38677, USA
50
Universite
́
de Montre
́
al, Physique des Particules, Montre
́
al, Que
́
bec, Canada H3C 3J7
51
Mount Holyoke College, South Hadley, Massachusetts 01075, USA
52a
INFN Sezione di Napoli, I-80126 Napoli, Italy
52b
Dipartimento di Scienze Fisiche, Universita
`
di Napoli Federico II, 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
57a
INFN Sezione di Padova, I-35131 Padova, Italy
57b
Dipartimento di Fisica, Universita
`
di Padova, I-35131 Padova, Italy
58
Laboratoire de Physique Nucle
́
aire et de Hautes Energies, IN2P3/CNRS, Universite
́
Pierre et Marie Curie-Paris6,
Universite
́
Denis Diderot-Paris7, F-75252 Paris, France
59
University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
60a
INFN Sezione di Perugia, I-06100 Perugia, Italy
60b
Dipartimento di Fisica, Universita
`
di Perugia, I-06100 Perugia, Italy
61a
INFN Sezione di Pisa, I-56127 Pisa, Italy
61b
Dipartimento di Fisica, Universita
`
di Pisa, I-56127 Pisa, Italy
61c
Scuola Normale Superiore di Pisa, I-56127 Pisa, Italy
62
Princeton University, Princeton, New Jersey 08544, USA
63a
INFN Sezione di Roma, I-00185 Roma, Italy
63b
Dipartimento di Fisica, Universita
`
di Roma La Sapienza, I-00185 Roma, Italy
64
Universita
̈
t Rostock, D-18051 Rostock, Germany
65
Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, OX11 0QX, United Kingdom
66
CEA, Irfu, SPP, Centre de Saclay, F-91191 Gif-sur-Yvette, France
67
University of South Carolina, Columbia, South Carolina 29208, USA
68
Stanford Linear Accelerator Center, Stanford, California 94309, USA
69
Stanford University, Stanford, California 94305-4060, USA
70
State University of New York, Albany, New York 12222, USA
71
University of Tennessee, Knoxville, Tennessee 37996, USA
72
University of Texas at Austin, Austin, Texas 78712, USA
73
University of Texas at Dallas, Richardson, Texas 75083, USA
**
Also with Universita
`
di Sassari, Sassari, Italy
{
Now at University of South Alabama, Mobile, AL 36688, USA
k
Also with Universita
`
di Roma La Sapienza, I-00185 Roma, Italy
x
Also with Universita
`
di Perugia, Dipartimento di Fisica, Perugia, Italy
Now at Tel Aviv University, Tel Aviv, 69978, Israel
+
Now at Temple University, Philadelphia, PA 19122, USA
*
Deceased
OBSERVATION OF
B
0
!

c
0
K

0
...
PHYSICAL REVIEW D
78,
091101(R) (2008)
RAPID COMMUNICATIONS
091101-3
74a
INFN Sezione di Torino, I-10125 Torino, Italy
74b
Dipartimento di Fisica Sperimentale, Universita
`
di Torino, I-10125 Torino, Italy
75a
INFN Sezione di Trieste, I-34127 Trieste, Italy
75b
Dipartimento di Fisica, Universita
`
di Trieste, I-34127 Trieste, Italy
76
IFIC, Universitat de Valencia-CSIC, E-46071 Valencia, Spain
77
University of Victoria, Victoria, British Columbia, Canada V8W 3P6
78
Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom
79
University of Wisconsin, Madison, Wisconsin 53706, USA
(Received 11 August 2008; published 6 November 2008)
We present the observation of the decay
B
0
!

c
0
K

0
as well as evidence of
B
þ
!

c
0
K
, with an 8.9
and a 3.6 standard deviation significance, respectively, using a data sample of
454

10
6

ð
4S
Þ!
B

B
decays collected with the
BABAR
detector at the PEP-II
B
meson factory located at the Stanford Linear
Accelerator Center (SLAC). The measured branching fractions are
B
ð
B
0
!

c
0
K

0
Þ¼ð
1
:
7

0
:
3

0
:
2
Þ
10

4
and
B
ð
B
þ
!

c
0
K
Þ¼ð
1
:
4

0
:
5

0
:
2
Þ
10

4
, where the first quoted errors are statis-
tical and the second are systematic. We obtain a branching fraction upper limit of
B
ð
B
þ
!

c
0
K
Þ
<
2
:
1

10

4
at the 90% confidence level.
DOI:
10.1103/PhysRevD.78.091101
PACS numbers: 13.25.Hw
Theoretical predictions of branching fractions and rate
asymmetries in nonleptonic heavy-flavor meson decays are
difficult due to our limited understanding of the process of
quark hadronization. In the simplest approximation, weak
decays such as
B
!
J=
c
K
arise from the quark-level
process
b
!
c

cs
through a current-current interaction
that can be written as
½

c

ð
1


5
Þ
c

s

ð
1


5
Þ
b

,
where


are Dirac matrices (

¼
0
, 1, 2, 3),

5
¼

0

1

2

3
and

c
,
c
,

s
,
b
are quark spinor fields. The
colorless current

c

ð
1


5
Þ
c
, which can create the
J=
c
, can also create the
P
-wave state

c
1
. It cannot,
however, create the

c
0
,

c
2
or
h
c
states, so their appear-
ance would have to be explained by a more complex
hypothesis. A theoretical prediction can be obtained with
the factorization hypothesis [
1
], assuming that the weak
decay matrix element can be described as a product of two
independent hadronic currents. Under the factorization
hypothesis,
B
!
c

cK
ðÞ
decays are allowed when the
c

c
pair hadronizes to
J=
c
,
c
ð
2
S
Þ
or

c
1
, but suppressed when
the
c

c
pair hadronizes to

c
0
[
2
]. In lowest-order Heavy
Quark Effective Theory, the decay rate to the scalar

c
0
is
zero due to charge conjugation invariance [
3
].
The decay
B
þ
!

c
0
K
þ
has been observed by Belle and
BABAR
with an average branching fraction (
B
)of
ð
1
:
40
þ
0
:
23

0
:
19
Þ
10

4
[
4
], using

c
0
decays to
K
þ
K

or

þ


. This result is of the same order of magnitude as
the branching fraction of the decay
B
þ
!

c
1
K
þ
,
ð
4
:
9

0
:
5
Þ
10

4
[
4
], and is surprisingly large given the expec-
tation from factorization. Using the hadronic

c
0
decays,
Belle has obtained an upper limit on
B
0
!

c
0
K
0
of
1
:
1

10

4
at 90% confidence level [
5
]. No predictions are
available for
B
decays to

c
0
K

, so the branching fraction
measurement of
B
!

c
0
K

should improve our under-
standing of the limitations of factorization and of models
that do not rely on factorization.
In this paper we report the first observation of
B
0
!

c
0
K

0
and find evidence of the decay
B
þ
!

c
0
K
[
6
].
We identify

c
0
mesons through their decays to
h
þ
h

(
h
¼
K
,

), as

c
0
!
K
þ
K

and

c
0
!

þ


have a higher
branching fraction than the radiative decay to
J=
c

(
J=
c
!
l
þ
l

,
l
¼

or
e
), that was used in the previous
search for
B
!

c
0
K

[
7
]. We identify
K
mesons
through their decay to
K
0
S

þ
, where
K
0
S
!

þ


, and
K

0
mesons through their decay to
K
þ


.
The data on which this analysis is based were collected
with the
BABAR
detector [
8
] at the PEP-II asymmetric-
energy
e
þ
e

storage ring. The
BABAR
detector consists of
a double-sided five-layer silicon tracker, a 40-layer drift
chamber, a Cherenkov detector, an electromagnetic calo-
rimeter, and a magnet with instrumented flux return (IFR)
consisting of layers of iron interspersed with resistive plate
chambers and limited streamer tubes. The data sample has
an integrated luminosity of
413 fb

1
collected at the

ð
4S
Þ
resonance, which corresponds to
ð
454

5
Þ
10
6
B

B
pairs. It is assumed that the

ð
4S
Þ
decays equally to neutral
and charged
B
meson pairs. In addition,
41 fb

1
of data
collected 40 MeV below the

ð
4S
Þ
resonance (off-
resonance data) are used for background studies.
Candidate
B
mesons are reconstructed from five tracks
for charged
B
decays and four tracks for neutral
B
decays,
where three and four tracks, respectively, are consistent
with originating from a common decay point within the
PEP-II luminous region. Each of the tracks is required to
have a transverse momentum greater than
50 MeV
=c
and
an absolute momentum less than
10 GeV
=c
. The tracks are
identified as either pion or kaon candidates, with protons
vetoed, using Cherenkov-angle information and ionization
energy-loss rate (
d
E=
d
x
) measurements. The efficiency for
kaon selection is approximately 80%, including geometric
acceptance, while the probability of misidentification of
pions as kaons is below 5% up to a laboratory momentum
of
4 GeV
=c
. Muons are rejected using information pre-
dominantly from the IFR. Furthermore, the tracks are
required to fail an electron selection based on their ratio
B. AUBERT
et al.
PHYSICAL REVIEW D
78,
091101(R) (2008)
RAPID COMMUNICATIONS
091101-4
of energy deposited in the calorimeter to momentum mea-
sured in the drift chamber, shower shape in the calorimeter,
d
E=
d
x
, and Cherenkov-angle information. Candidate
K
0
S
mesons are reconstructed from

þ


candidates, and are
required to have a reconstructed mass within
15 MeV
=c
2
of the nominal
K
0
mass [
4
], a decay vertex separated from
the
B
þ
decay vertex with a significance of at least 5
standard deviations, a flight distance in the transverse
direction of at least 0.3 cm and a cosine of the angle
between the line joining the
B
and
K
0
S
decay vertices and
the
K
0
S
momentum greater than 0.999.
Four kinematic variables and one event-shape variable
are used to characterize signal events. The first kinematic
variable,

E
, is the difference between the center-of-mass
(c.m.) energy of the
B
candidate and
ffiffiffi
s
p
=
2
, where
ffiffiffi
s
p
is the
total c.m. energy. The second is the beam-energy-
substituted mass
m
ES
¼
ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
ð
s=
2
þ
p
i

p
B
Þ
2
=E
2
i

p
2
B
q
,
where
p
B
is the reconstructed momentum of the
B
candi-
date, and the four-momentum of its parent

ð
4S
Þ
in the
laboratory frame,
ð
E
i
;
p
i
Þ
, is determined from nominal
colliding beam parameters. The third kinematic variable
is the
K
invariant mass,
m
K

, used to identify
K

candi-
dates, where
K
is
K
0
S

þ
or
K
þ


for
K
or
K

0
candidates, respectively. The fourth kinematic variable is
the
h
þ
h

invariant mass,
m
hh
, used to identify

c
0
candi-
dates. Candidate
B
mesons are required to satisfy
j

E
j
<
0
:
1 GeV
,
5
:
25
<m
ES
<
5
:
29 GeV
=c
2
,
0
:
772
ð
0
:
776
Þ
<
m
K

<
0
:
992
ð
0
:
996
Þ
GeV
=c
2
for
B
þ
ð
B
0
Þ
candidates and
3
:
35
<m
hh
<
3
:
50 GeV
=c
2
. The event-shape variable is
a Fisher discriminant
F
[
9
], constructed as a linear combi-
nation of the absolute value of the cosine of the angle
between the
B
candidate momentum and the beam axis,
the absolute value of the cosine of the angle between the
thrust axis of the decay products of the
B
candidate and the
beam axis, and the zeroth and second angular moments of
energy flow about the thrust axis of the reconstructed
B
.
Continuum quark production (
e
þ
e

!
q

q
, where
q
¼
u
,
d
,
s
,
c
) is the dominant source of background. It is
suppressed using another event-shape variable,
j
cos

T
j
,
which is the absolute value of the cosine of the angle

T
between the thrust axis [
10
] of the selected
B
candidate and
the thrust axis of the rest of the event. For continuum
background, the distribution of
j
cos

T
j
is strongly peaked
towards 1 whereas the distribution is essentially flat for
signal events. Therefore, the relative amount of continuum
background is reduced by requiring
j
cos

T
j
<
0
:
9
.
Backgrounds from other
B
meson decays are studied
with Monte Carlo (MC) events, using at least
10
3
times the
number of events expected in data for specific decay modes
that are the possible sources of background for this
analysis.
Potential charm contributions from
B
!
D
ð!
K

h

Þ
h
þ
events are removed by vetoing events with a reconstructed
K

h

invariant mass in the range
1
:
83
<m
K

h
<
1
:
91 GeV
=c
2
. To remove background from
D
0
mesons, a
veto is applied to any
K
pair with an invariant mass in
the range
1
:
83
<m
K
<
1
:
91 GeV
=c
2
for each
B
!

c
0
ð!
h
þ
h

Þ
K

decay. Studies of MC events show that
the largest remaining charmed backgrounds are
B
þ
!

D
0
ð!
K
0
S

þ


Þ

þ
and
B
0
!
D

ð!
K
þ




Þ

þ
,
with 12% and 10% passing the veto, respectively.
Surviving charmed events have a reconstructed
D
mass
outside the veto range as a result of using a

or
K
candidate that is incorrectly selected from the other
B
decay in the event.
A fraction of signal events has more than one
B
candi-
date reconstructed. For those events, the candidate with the
highest

2
probability of the fitted
B
decay vertex is
selected. Studies of MC events show that less than 11%
of events are reconstructed from the wrong candidate,
where these incorrectly reconstructed events are modeled
in the fit to data.
After applying all selection criteria, there are five main
categories of background from
B
decays: two- and three-
body decays proceeding via a
D
meson; nonresonant
B
!
K

h
þ
h

and
B
!
K
c
0
; combinatorial background
from three unrelated particles (
K

h
þ
h

); two- or four-
body
B
decays with an extra or missing particle and
three-body decays with one or more particles misidenti-
fied. Along with selection efficiencies obtained from MC
simulation, existing branching fractions for these modes
[
4
,
11
] are used to estimate their background contributions
that are included separately and fixed in fits to data. For the
nonresonant backgrounds, where there is no branching
fraction information, fits to sideband data (
0
:
996
<m
K

<
1
:
53 GeV
=c
2
and
3
:
2
<m
hh
<
3
:
35 GeV
=c
2
) are per-
formed to estimate the background contributions.
In order to extract the signal event yield for the channel
under study, an unbinned extended maximum likelihood fit
is used. The likelihood function for
N
events is
L
¼
1
N
!
exp


X
M
i
¼
1
n
i

Y
N
j
¼
1

X
M
i
¼
1
n
i
P
i
ð
~
;
~
x
j
Þ

;
(1)
where
M
¼
3
is the number of hypotheses (signal, contin-
uum background, and
B
background),
n
i
is the number of
events for each hypothesis determined by maximizing the
likelihood function, and
P
i
ð
~
;
~
x
j
Þ
is a probability density
function (PDF) with the parameters
~

and variables
~
x
¼
ð
m
ES
;

E;
F
;m
K

and
m
hh
Þ
. The PDF is a product
P
i
ð
~
;
~
x
Þ¼
P
i
ð
~

m
ES
;m
ES
Þ
P
i
ð
~


E
;

E
Þ
P
i
ð
~

F
;
F
Þ
P
i
ð
~

m
K

;m
K

Þ
P
i
ð
~

m
hh
;m
hh
Þ
. Studies of MC simulation
show that correlations between these variables are small
for the signal and continuum background hypotheses.
However, for
B
background, correlations of a few percent
are observed between
m
ES
and

E
, which are taken into
account by forming a 2-dimensional PDF for these
variables.
The parameters for signal and
B
background PDFs are
determined from MC simulation. All continuum back-
OBSERVATION OF
B
0
!

c
0
K

0
...
PHYSICAL REVIEW D
78,
091101(R) (2008)
RAPID COMMUNICATIONS
091101-5
ground parameters are allowed to vary in the fit, in order to
help reduce systematic effects from this dominant event
type. Sideband data, defined to be in the region
0
:
1
<

E<
0
:
3 GeV
and
5
:
25
<m
ES
<
5
:
29 GeV
=c
2
, as well
as off-resonance data, are used to model the continuum
background PDFs. For the
m
ES
PDFs, a Gaussian distribu-
tion is used for signal and a threshold function [
12
] for
continuum background. For the

E
PDFs, a sum of two
Gaussian distributions with distinct means and widths is
used for the signal and a first-order polynomial for the
continuum background. A two-dimensional
ð
m
ES
;

E
Þ
his-
togram is used for
B
background. The signal, continuum
and
B
background
F
PDFs are described using a sum of
two Gaussian distributions with distinct means and widths.
For
m
K

PDFs, a sum of a relativistic Breit-Wigner func-
tion [
4
] and a first-order polynomial describes each of the
signal, continuum, and
B
background distributions. Within
the
m
K

fit range, there is also the possibility of
B
back-
ground contributions from nonresonant and higher
K

resonances; these contributions are modeled in the fit using
the LASS parametrization [
13
,
14
]. The contribution from
this background is estimated by extrapolating a
K
invari-
ant mass projection fitted in a higher-mass region
(
0
:
996
<m
K

<
1
:
53 GeV
=c
2
) into the signal region.
This estimated background is modeled in the final fit to
the signal region and assumes there are no interference
effects between the
K
background and the
K

ð
892
Þ
sig-
nal. Finally, for
m
hh
PDFs, a sum of a relativistic Breit-
Wigner function and a first-order polynomial is used to
describe the signal and a first-order polynomial to describe
the continuum and
B
background distributions. The non-
resonant
h
þ
h

background is modeled by a first-order
polynomial, and the background is estimated by extrapo-
lating the invariant mass projection fitted in the lower mass
region (
3
:
2
<m
hh
<
3
:
35 GeV
=c
2
) into the signal region.
The signal first-order polynomial component of the
m
K

and
m
hh
PDFs is used to model misreconstructed events;
for example, where a
K
þ
from the
K

0
is reconstructed as a

c
0
daughter particle, and vice versa.
To extract the
B
!

c
0
K

branching fractions,
B
, the
following equation is used:
B
¼
n
sig
N
BB



B
ð

c
0
!
h
þ
h

Þ
;
(2)
where
n
sig
is the number of signal events fitted,

is the
signal efficiency obtained from MC and
N
BB
is the total
number of
B

B
events. The efficiencies take into account
both
B
ð
K
!
K
0

þ
Þ¼
2
=
3
and
B
ð
K

0
!
K
þ


Þ¼
2
=
3
, assuming isospin symmetry, as well as
B
ð
K
0
!
K
0
S
Þ¼
1
=
2
and
B
ð
K
0
S
!

þ


Þ
[
4
]. The branching frac-
tions are calculated taking into account
B
ð

c
0
!
K
þ
K

Þ¼ð
5
:
5

0
:
6
Þ
10

3
and
B
ð

c
0
!

þ


Þ¼
ð
7
:
3

0
:
6
Þ
10

3
[
4
].
We observe the decay
B
0
!

c
0
K

0
with an 8.9 standard
deviation significance and measure the branching fraction
B
ð
B
0
!

c
0
K

0
Þ¼ð
1
:
7

0
:
3

0
:
2
Þ
10

4
. We find
evidence for
B
þ
!

c
0
K
with a 3.6 standard deviation
significance and set a 90% confidence level upper limit on
the branching fraction of
2
:
1

10

4
. Figure
1
shows the
fitted
m
ES
and
m
hh
projections for the
B
þ
!

c
0
K
ð

c
0
!
K
þ
K

Þ
,
B
þ
!

c
0
K
ð

c
0
!

þ


Þ
,
B
0
!

c
0
K

0
ð

c
0
!
K
þ
K

Þ
and
B
0
!

c
0
K

0
ð

c
0
!

þ


Þ
candidates, while the fitted signal yields; measured
branching fractions and upper limits are shown in Table
I
.
The candidates in Fig.
1
are signal-enhanced, with a re-
quirement on the probability ratio
P
sig
=
ð
P
sig
þ
P
bkg
Þ
,
optimized to enhance the visibility of potential signal,
where
P
sig
and
P
bkg
are the signal and the total back-
ground probabilities, respectively (computed without using
the variable plotted). Figure
2
shows the

2ln
L
distribu-
tions for both
B
þ
!

c
0
K
and
B
0
!

c
0
K

0
as a func-
tion of the branching fraction. The

2ln
L
distributions for
the final states (

c
0
!
K
þ
K

and

c
0
!

þ


) are com-
bined to give final the branching fractions shown in Table
I
.
The 90% confidence level branching fraction upper limit
(
B
UL
) is determined by integrating the likelihood distribu-
tion (with systematic uncertainties included) as a function
of the branching fraction from 0 to
B
UL
, so that
R
B
UL
0
L
d
B
¼
0
:
9
R
1
0
L
d
B
. The signal significance
S
,in
5
10
(a)
5
10
(b)
20
(c)
10
20
(d)
20
(e)
10
20
(f)
50
(g)
20
40
(h)
5.25 5.26 5.27 5.28 5.29
)
2
(GeV/c
ES
m
3.35
3.40
3.45
3.50
)
2
(GeV/c
hh
m
Events / 2 MeV/
Events / 10 MeV
FIG. 1 (color online). Maximum likelihood fit projections of
m
ES
(left column) and
m
hh
(right column) for signal-enhanced
samples of
B
!

c
0
K

candidates. The dashed line is the fitted
background PDF while the solid line is the sum of the signal and
background PDFs. The points indicate the data. The plot shows
projections for
B
þ
!

c
0
K
ð

c
0
!
K
þ
K

Þ
(a) and (b), for
B
þ
!

c
0
K
ð

c
0
!

þ


Þ
(c) and (d), for
B
0
!

c
0
K

0
ð

c
0
!
K
þ
K

Þ
(e) and (f), and
B
0
!

c
0
K

0
ð

c
0
!

þ


Þ
(g) and (f).
B. AUBERT
et al.
PHYSICAL REVIEW D
78,
091101(R) (2008)
RAPID COMMUNICATIONS
091101-6
units of standard deviation, is defined as
ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
2 ln
L
p
, where
ln
L
represents the change in log-likelihood (with sys-
tematic uncertainties included) between the maximum
value and the value when the signal yield is set to zero.
Contributions to the branching fraction systematic un-
certainty are shown in Table
II
. The presence of a non-
resonant
K
þ
K

and

þ


can give rise to interference
effects, resulting in a departure from the
m
hh
PDF used in
the fit to data. In order to estimate how much this can affect
the extracted yields, the fit is repeated with the inclusion of
a PDF describing the interference between the Breit-
Wigner and nonresonant amplitudes in the
m
hh
distribu-
tion. This shape consists of the squared modulus of the sum
of a Breit-Wigner and a constant amplitude, carrying an
arbitrary phase difference. The relative weight of these two
components and their phase difference are allowed to vary
to obtain the best fit. The signal yields derived from this fit
are larger than the nominal fit in Table
I
, and the difference
from the nominal fit is used as an estimate of the systematic
error in Table
II
due to neglecting interference effects.
Interference effects between the
K

ð
892
Þ
and spin-0 final
states (nonresonant and
K

0
ð
1430
Þ
) integrate to zero if the
acceptance of the detector and analysis is uniform; the
same is true of the interference between the
K

ð
892
Þ
and
TABLE I. Total number of events in the fit,
B
background yields (
B
bkg), signal yields, efficiencies, and branching fractions
B
,
measured using
B
!

c
0
K

events. Fit bias corrections are applied to the signal yields and branching fractions. The first error is
statistical and the second error is systematic. The significance
S
is shown for
B
þ
!

c
0
K
and
B
0
!

c
0
K

0
and the branching
fraction upper limit,
B
UL
, at the 90% confidence level is shown for
B
þ
!

c
0
K
.
Mode
Total Events
B
bkg Signal Yield Signal Efficiency (%)
B
(

10

4
)
B
UL
(

10

4
)
S
(

)
B
þ
!

c
0
K

c
0
!
K
þ
K

156
8
13

5
3.2
1
:
6

0
:
7

0
:
2

c
0
!

þ


1065
65
15

9
3.8
1
:
2

0
:
7

0
:
2
Combined
1
:
4

0
:
5

0
:
2
2.1
3.6
B
0
!

c
0
K

0

c
0
!
K
þ
K

690
20
47

10
11.1
1
:
7

0
:
4

0
:
2

c
0
!

þ


4507
154
72

15
12.8
1
:
7

0
:
4

0
:
2
Combined
1
:
7

0
:
3

0
:
2
8.9
TABLE II. Summary of systematic uncertainty contributions
to the branching fraction measurements
B
!

c
0
K

.
Multiplicative and additive errors are shown as a percentage of
the branching fraction. The final row shows the total systematic
error on the branching fractions.
Error

c
0
K

c
0
K

c
0
K

0

c
0
K

0
Source

c
0
ð
KK
Þ

c
0
ð

Þ

c
0
ð
KK
Þ

c
0
ð

Þ
Multiplicative errors (%)
Interference
7.2
8.3
6.8
10.1
Tracking
4.0
4.0
3.2
3.2
K
0
S
Efficiency
1.7
1.7
-
-
Particle ID
1.9
2.7
2.4
3.2
B
ð

c
0
!
h
þ
h

Þ
10.9
8.2
10.9
8.2
No. of
B

B
1.1
1.1
1.1
1.1
Tot. mult. (%)
13.9
12.8
13.8
13.8
Additive errors (%)
Fit Bias
1.3
4.4
1.8
3.9
B
background
0.5
4.5
1.4
1.5
PDF params.
0.6
3.4
0.3
2.6
Tot. add. (%)
1.5
7.2
2.3
4.9
Total (
10

4
)
0.2
0.2
0.2
0.2
)
-4
10
×
)(
*+
K
c0
χ
+
B(B
012345
)
0
-2 ln (L/L
0
5
10
15
20
25
30
35
40
45
a)
)
-4
10
×
)(
*0
K
c0
χ
0
B(B
0
0.5
1
1.5
2
2.5
3
3.5
4
)
0
-2 ln (L/L
0
10
20
30
40
50
60
70
80
90
100
b)
FIG. 2 (color online). Distribution of

2ln
L
as a function of
branching fraction for
B
þ
!

c
0
K
(a) and
B
0
!

c
0
K

0
(b).
In each case, the upper dashed line is the decay

c
0
!
K
þ
K

and the lower dashed line is the decay

c
0
!

þ


. The solid
line is the combination of the two. In all cases systematics
contributions are included and the

2ln
L
distributions have
been shifted vertically so the minimum value is 0.
OBSERVATION OF
B
0
!

c
0
K

0
...
PHYSICAL REVIEW D
78,
091101(R) (2008)
RAPID COMMUNICATIONS
091101-7
spin-2 final states (
K

2
ð
1430
Þ
). Studies of MC events show
the efficiency variations are small enough to consider these
interference effects insignificant. The integrated interfer-
ence between
K

ð
892
Þ
and other spin-1 amplitudes such as
K

ð
1410
Þ
is in principle nonzero, but in practice is negli-
gible due to the small branching fraction of
K

ð
1410
Þ!
K
þ


(
6
:
6

1
:
3%
[
4
]) and the fact that the
K
mass
lineshapes have little overlap. Errors due to tracking effi-
ciency,
K
0
S
reconstruction efficiency and particle identifi-
cation are assigned by comparing control channels in MC
simulation and data. The branching fraction error of

c
0
!
h
þ
h

is taken from the combination of previous measure-
ments [
4
]. The number of
B

B
events is determined with an
uncertainty of 1.1%. To estimate errors due to the fit
procedure, 500 MC samples containing the numbers of
signal and continuum events measured in data and the
estimated number of exclusive
B
background events are
used. The differences between the generated and fitted
values are used to estimate small fit biases (see Table
II
)
that are a consequence of correlations between fit varia-
bles. These biases are applied as corrections to obtain the
final signal yields, and half of the correction is added as a
systematic uncertainty. The uncertainty of the
B
back-
ground contribution to the fit is estimated by varying the
known branching fractions within their errors. Each back-
ground is varied individually and the effect on the fitted
signal yield is added in quadrature as a contribution to the
uncertainty. The uncertainty due to PDF modeling is esti-
mated by varying the PDFs by the parameter errors. In
order to take correlations between parameters into account,
the full correlation matrix is used when varying the pa-
rameters. All PDF parameters that are originally fixed in
the fit are then varied in turn, and each difference from the
nominal fit is combined in quadrature and taken as a
systematic contribution.
In summary, we have observed the decay
B
0
!

c
0
K

0
with an 8.9 standard deviation significance and find evi-
dence for
B
þ
!

c
0
K
with a 3.6 standard deviation
significance, placing an upper limit on the branching frac-
tion. The
B
0
!

c
0
K

0
branching fraction does not agree
with the zero value expected from the color-singlet current-
current contribution alone, and is approximately half the
B
0
!

c
1
K

0
branching fraction (
ð
3
:
2

0
:
6
Þ
10

4
[
4
]),
which is surprising when taking into account factorization
expectations.
We are grateful for the excellent luminosity and machine
conditions provided by our PEP-II colleagues, and for the
substantial dedicated effort from the computing organiza-
tions that support
BABAR
. The collaborating institutions
wish to thank SLAC for its support and kind hospitality.
This work is supported by DOE and NSF (USA), NSERC
(Canada), CEA and CNRS-IN2P3 (France), BMBF and
DFG (Germany), INFN (Italy), FOM (The Netherlands),
NFR (Norway), MIST (Russia), MEC (Spain), and STFC
(United Kingdom). Individuals have received support from
the Marie Curie EIF (European Union) and the A. P. Sloan
Foundation.
[1] M. Bauer, B. Stech, and M. Wirbel, Z. Phys. C
34
, 103
(1987).
[2] M. Suzuki, Phys. Rev. D
66
, 037503 (2002).
[3] M. Diehl and G. Hiller, J. High Energy Phys. 06 (2001)
067.
[4] W. M. Yao
et al.
(Particle Data Group), J. Phys. G
33
,1
(2006), and 2007 partial update for the 2008 edition.
[5] A. Garmash
et al.
(Belle Collaboration), Phys. Rev. D
75
,
012006 (2007).
[6] The use of charge-conjugate modes is implied throughout
this paper unless otherwise noted.
[7] B. Aubert
et al.
(
BABAR
Collaboration), Phys. Rev. Lett.
94
, 171801 (2005).
[8] B. Aubert
et al.
(
BABAR
Collaboration), Nucl. Instrum.
Methods Phys. Res., Sect. A
479
, 1 (2002).
[9] R. A. Fisher, Ann. Eugenics
7
, 179 (1936); G. Cowan,
Statistical Data Analysis
(Oxford University Press, New
York, 1998), Vol. 51.
[10] S. Brandt
et al.
, Phys. Lett.
12
, 57 (1964); E. Fahri, Phys.
Rev. Lett.
39
, 1587 (1977).
[11] The Heavy Flavor Averaging Group (HFAG), http://
www.slac.stanford.edu/xorg/hfag/.
[12] H. Albrecht
et al.
(ARGUS Collaboration), Z. Phys. C
48
,
543 (1990).
[13] D. Aston
et al.
, Nucl. Phys.
B296
, 493 (1988).
[14] B. Aubert
et al.
(
BABAR
Collaboration), Phys. Rev. D
72
,
072003 (2005).
B. AUBERT
et al.
PHYSICAL REVIEW D
78,
091101(R) (2008)
RAPID COMMUNICATIONS
091101-8