of 12
Study of
B

;
0
J
=
ψ
K
þ
K
K

;
0
and search for
B
0
J
=
ψφ
at
B
A
B
AR
J. P. Lees,
1
V. Poireau,
1
V. Tisserand,
1
E. Grauges,
2
A. Palano,
3a,3b
G. Eigen,
4
B. Stugu,
4
D. N. Brown,
5
L. T. Kerth,
5
Yu.
G. Kolomensky,
5
M. J. Lee,
5
G. Lynch,
5
H. Koch,
6
T. Schroeder,
6
C. Hearty,
7
T. S. Mattison,
7
J. A. McKenna,
7
R. Y. So,
7
A. Khan,
8
V. E. Blinov,
9a,9c
A. R. Buzykaev,
9a
V. P. Druzhinin,
9a,9b
V. B. Golubev,
9a,9b
E. A. Kravchenko,
9a,9b
A. P. Onuchin,
9a,9c
S. I. Serednyakov,
9a,9b
Yu. I. Skovpen,
9a,9b
E. P. Solodov,
9a,9b
K. Yu. Todyshev,
9a,9b
A. N. Yushkov,
9a
A. J. Lankford,
10
M. Mandelkern,
10
B. Dey,
11
J. W. Gary,
11
O. Long,
11
C. Campagnari,
12
M. Franco Sevilla,
12
T. M. Hong,
12
D. Kovalskyi,
12
J. D. Richman,
12
C. A. West,
12
A. M. Eisner,
13
W. S. Lockman,
13
W. Panduro Vazquez,
13
B. A. Schumm,
13
A. Seiden,
13
D. S. Chao,
14
C. H. Cheng,
14
B. Echenard,
14
K. T. Flood,
14
D. G. Hitlin,
14
T. S. Miyashita,
14
P. Ongmongkolkul,
14
F. C. Porter,
14
R. Andreassen,
15
Z. Huard,
15
B. T. Meadows,
15
B. G. Pushpawela,
15
M. D. Sokoloff,
15
L. Sun,
15
P. C. Bloom,
16
W. T. Ford,
16
A. Gaz,
16
U. Nauenberg,
16
J. G. Smith,
16
S. R. Wagner,
16
R. Ayad,
17
,
W. H. Toki,
17
B. Spaan,
18
R. Schwierz,
19
D. Bernard,
20
M. Verderi,
20
S. Playfer,
21
D. Bettoni,
22a
C. Bozzi,
22a
R. Calabrese,
22a,22b
G. Cibinetto,
22a,22b
E. Fioravanti,
22a,22b
I. Garzia,
22a,22b
E. Luppi,
22a,22b
L. Piemontese,
22a
V. Santoro,
22a
A. Calcaterra,
23
R. de
Sangro,
23
G. Finocchiaro,
23
S. Martellotti,
23
P. Patteri,
23
I. M. Peruzzi,
23
,
M. Piccolo,
23
M. Rama,
23
A. Zallo,
23
R. Contri,
24a,24b
E. Guido,
24a,24b
M. Lo Vetere,
24a,24b
M. R. Monge,
24a,24b
S. Passaggio,
24a
C. Patrignani,
24a,24b
E. Robutti,
24a
B. Bhuyan,
25
V. Prasad,
25
M. Morii,
26
A. Adametz,
27
U. Uwer,
27
H. M. Lacker,
28
P. D. Dauncey,
29
U. Mallik,
30
C. Chen,
31
J. Cochran,
31
W. T. Meyer,
31
S. Prell,
31
H. Ahmed,
32
A. V. Gritsan,
33
N. Arnaud,
34
M. Davier,
34
D. Derkach,
34
G. Grosdidier,
34
F. Le Diberder,
34
A. M. Lutz,
34
B. Malaescu,
34
P. Roudeau,
34
A. Stocchi,
34
G. Wormser,
34
D. J. Lange,
35
D. M. Wright,
35
J. P. Coleman,
36
J. R. Fry,
36
E. Gabathuler,
36
D. E. Hutchcroft,
36
D. J. Payne,
36
C. Touramanis,
36
A. J. Bevan,
37
F. Di Lodovico,
37
R. Sacco,
37
G. Cowan,
38
J. Bougher,
39
D. N. Brown,
39
C. L. Davis,
39
A. G. Denig,
40
M. Fritsch,
40
W. Gradl,
40
K. Griessinger,
40
A. Hafner,
40
E. Prencipe,
40
,
K. R. Schubert,
40
R. J. Barlow,
41
G. D. Lafferty,
41
R. Cenci,
42
B. Hamilton,
42
A. Jawahery,
42
D. A. Roberts,
42
R. Cowan,
43
D. Dujmic,
43
G. Sciolla,
43
R. Cheaib,
44
P. M. Patel,
44
,*
S. H. Robertson,
44
P. Biassoni,
45a,45b
N. Neri,
45a
F. Palombo,
45a,45b
L. Cremaldi,
46
R. Godang,
46
,**
P. Sonnek,
46
D. J. Summers,
46
M. Simard,
47
P. Taras,
47
G. De Nardo,
48a,48b
D. Monorchio,
48a,48b
G. Onorato,
48a,48b
C. Sciacca,
48a,48b
M. Martinelli,
49
G. Raven,
49
C. P. Jessop,
50
J. M. LoSecco,
50
K. Honscheid,
51
R. Kass,
51
J. Brau,
52
R. Frey,
52
N. B. Sinev,
52
D. Strom,
52
E. Torrence,
52
E. Feltresi,
53a,53b
M. Margoni,
53a,53b
M. Morandin,
53a
M. Posocco,
53a
M. Rotondo,
53a
G. Simi,
53a,53b
F. Simonetto,
53a,53b
R. Stroili,
53a,53b
S. Akar,
54
E. Ben-Haim,
54
M. Bomben,
54
G. R. Bonneaud,
54
H. Briand,
54
G. Calderini,
54
J. Chauveau,
54
Ph. Leruste,
54
G. Marchiori,
54
J. Ocariz,
54
S. Sitt,
54
M. Biasini,
55a,55b
E. Manoni,
55a
S. Pacetti,
55a,55b
A. Rossi,
55a
C. Angelini,
56a,56b
G. Batignani,
56a,56b
S. Bettarini,
56a,56b
M. Carpinelli,
56a,56b
,
††
G. Casarosa,
56a,56b
A. Cervelli,
56a,56b
M. Chrzaszcz,
56a,56b
F. Forti,
56a,56b
M. A. Giorgi,
56a,56b
A. Lusiani,
56a,56c
B. Oberhof,
56a,56b
E. Paoloni,
56a,56b
A. Perez,
56a
G. Rizzo,
56a,56b
J. J. Walsh,
56a
D. Lopes Pegna,
57
J. Olsen,
57
A. J. S. Smith,
57
R. Faccini,
58a,58b
F. Ferrarotto,
58a
F. Ferroni,
58a,58b
M. Gaspero,
58a,58b
L. Li Gioi,
58a
G. Piredda,
58a
C. Bünger,
59
S. Dittrich,
59
O. Grünberg,
59
T. Hartmann,
59
T. Leddig,
59
C. Voß,
59
R. Waldi,
59
T. Adye,
60
E. O. Olaiya,
60
F. F. Wilson,
60
S. Emery,
61
G. Vasseur,
61
F. Anulli,
62
,
‡‡
D. Aston,
62
D. J. Bard,
62
J. F. Benitez,
62
C. Cartaro,
62
M. R. Convery,
62
J. Dorfan,
62
G. P. Dubois-Felsmann,
62
W. Dunwoodie,
62
M. Ebert,
62
R. C. Field,
62
B. G. Fulsom,
62
A. M. Gabareen,
62
M. T. Graham,
62
C. Hast,
62
W. R. Innes,
62
P. Kim,
62
M. L. Kocian,
62
D. W. G. S. Leith,
62
P. Lewis,
62
D. Lindemann,
62
B. Lindquist,
62
S. Luitz,
62
V. Luth,
62
H. L. Lynch,
62
D. B. MacFarlane,
62
D. R. Muller,
62
H. Neal,
62
S. Nelson,
62
M. Perl,
62
T. Pulliam,
62
B. N. Ratcliff,
62
A. Roodman,
62
A. A. Salnikov,
62
R. H. Schindler,
62
A. Snyder,
62
D. Su,
62
M. K. Sullivan,
62
J. Va
vra,
62
A. P. Wagner,
62
W. F. Wang,
62
W. J. Wisniewski,
62
M. Wittgen,
62
D. H. Wright,
62
H. W. Wulsin,
62
V. Ziegler,
62
M. V. Purohit,
63
R. M. White,
63
,§§
J. R. Wilson,
63
A. Randle-Conde,
64
S. J. Sekula,
64
M. Bellis,
65
P. R. Burchat,
65
E. M. T. Puccio,
65
M. S. Alam,
66
J. A. Ernst,
66
R. Gorodeisky,
67
N. Guttman,
67
D. R. Peimer,
67
A. Soffer,
67
S. M. Spanier,
68
J. L. Ritchie,
69
A. M. Ruland,
69
R. F. Schwitters,
69
B. C. Wray,
69
J. M. Izen,
70
X. C. Lou,
70
F. Bianchi,
71a,71b
F. De Mori,
71a,71b
A. Filippi,
71a
D. Gamba,
71a,71b
S. Zambito,
71a,71b
L. Lanceri,
71a,71b
L. Vitale,
72a,72b
F. Martinez-Vidal,
73
A. Oyanguren,
73
P. Villanueva-Perez,
73
J. Albert,
74
Sw. Banerjee,
74
F. U. Bernlochner,
74
H. H. F. Choi,
74
G. J. King,
74
R. Kowalewski,
74
M. J. Lewczuk,
74
T. Lueck,
74
I. M. Nugent,
74
J. M. Roney,
74
R. J. Sobie,
74
N. Tasneem,
74
T. J. Gershon,
75
P. F. Harrison,
75
T. E. Latham,
75
H. R. Band,
76
S. Dasu,
76
Y. Pan,
76
R. Prepost,
76
and S. L. Wu
76
(
B
A
B
AR
Collaboration)
1
Laboratoire d
Annecy-le-Vieux de Physique des Particules (LAPP), Université de Savoie, CNRS/IN2P3,
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
Dipartimento di Fisica, Università di Bari, I-70126 Bari, Italy
4
University of Bergen, Institute of Physics, N-5007 Bergen, Norway
PHYSICAL REVIEW D
91,
012003 (2015)
1550-7998
=
2015
=
91(1)
=
012003(12)
012003-1
© 2015 American Physical Society
5
Lawrence Berkeley National Laboratory and University of California, Berkeley, California 94720, USA
6
Ruhr Universität Bochum, Institut für Experimentalphysik 1, D-44780 Bochum, Germany
7
University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
8
Brunel University, Uxbridge, Middlesex UB8 3PH, United Kingdom
9a
Budker Institute of Nuclear Physics SB RAS, Novosibirsk 630090, Russia;
9b
Novosibirsk State University, Novosibirsk 630090, Russia
9c
Novosibirsk State Technical University, Novosibirsk 630092, Russia
10
University of California at Irvine, Irvine, California 92697, USA
11
University of California at Riverside, Riverside, California 92521, USA
12
University of California at Santa Barbara, Santa Barbara, California 93106, USA
13
University of California at Santa Cruz, Institute for Particle Physics, Santa Cruz, California 95064, USA
14
California Institute of Technology, Pasadena, California 91125, USA
15
University of Cincinnati, Cincinnati, Ohio 45221, USA
16
University of Colorado, Boulder, Colorado 80309, USA
17
Colorado State University, Fort Collins, Colorado 80523, USA
18
Technische Universität Dortmund, Fakultät Physik, D-44221 Dortmund, Germany
19
Technische Universität Dresden, Institut für Kern- und Teilchenphysik, D-01062 Dresden, Germany
20
Laboratoire Leprince-Ringuet, Ecole Polytechnique, CNRS/IN2P3, F-91128 Palaiseau, France
21
University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom
22a
INFN Sezione di Ferrara, I-44122 Ferrara, Italy
22b
Dipartimento di Fisica e Scienze della Terra, Università di Ferrara, I-44122 Ferrara, Italy
23
INFN Laboratori Nazionali di Frascati, I-00044 Frascati, Italy
24a
INFN Sezione di Genova, I-16146 Genova, Italy
24a
Dipartimento di Fisica, Università di Genova, I-16146 Genova, Italy
25
Indian Institute of Technology Guwahati, Guwahati, Assam, 781 039, India
26
Harvard University, Cambridge, Massachusetts 02138, USA
27
Universität Heidelberg, Physikalisches Institut, D-69120 Heidelberg, Germany
28
Humboldt-Universität zu Berlin, Institut für Physik, D-12489 Berlin, Germany
29
Imperial College London, London SW7 2AZ, United Kingdom
30
University of Iowa, Iowa City, Iowa 52242, USA
31
Iowa State University, Ames, Iowa 50011-3160, USA
32
Physics Department, Jazan University, Jazan 22822, Kingdom of Saudi Arabia
33
Johns Hopkins University, Baltimore, Maryland 21218, USA
34
Laboratoire de l
Accélérateur Linéaire, IN2P3/CNRS et Université Paris-Sud 11, Centre Scientifique
d
Orsay, F-91898 Orsay Cedex, France
35
Lawrence Livermore National Laboratory, Livermore, California 94550, USA
36
University of Liverpool, Liverpool L69 7ZE, United Kingdom
37
Queen Mary, University of London, London E1 4NS, United Kingdom
38
University of London, Royal Holloway and Bedford New College, Egham,
Surrey TW20 0EX, United Kingdom
39
University of Louisville, Louisville, Kentucky 40292, USA
40
Johannes Gutenberg-Universität Mainz, Institut für Kernphysik, D-55099 Mainz, Germany
41
University of Manchester, Manchester M13 9PL, United Kingdom
42
University of Maryland, College Park, Maryland 20742, USA
43
Massachusetts Institute of Technology, Laboratory for Nuclear Science, Cambridge,
Massachusetts 02139, USA
44
McGill University, Montréal, Québec H3A 2T8, Canada
45a
INFN Sezione di Milano, I-20133 Milano, Italy;
45b
Dipartimento di Fisica, Università di Milano, I-20133 Milano, Italy
46
University of Mississippi, University, Mississippi 38677, USA
47
Université de Montréal, Physique des Particules, Montréal, Québec H3C 3J7, Canada
48a
INFN Sezione di Napoli, I-80126 Napoli, Italy;
48b
Dipartimento di Scienze Fisiche, Università di Napoli Federico II, I-80126 Napoli, Italy
49
NIKHEF, National Institute for Nuclear Physics and High Energy Physics,
NL-1009 DB Amsterdam, Netherlands
50
University of Notre Dame, Notre Dame, Indiana 46556, USA
51
Ohio State University, Columbus, Ohio 43210, USA
52
University of Oregon, Eugene, Oregon 97403, USA
53a
INFN Sezione di Padova, I-35131 Padova, Italy
53b
Dipartimento di Fisica, Università di Padova, I-35131 Padova, Italy
J. P. LEES
et al.
PHYSICAL REVIEW D
91,
012003 (2015)
012003-2
54
Laboratoire de Physique Nucléaire et de Hautes Energies, IN2P3/CNRS, Université Pierre et Marie
Curie-Paris 6, Université Denis Diderot-Paris7, F-75252 Paris, France
55a
INFN Sezione di Perugia, I-06123 Perugia, Italy
55b
Dipartimento di Fisica, Università di Perugia, I-06123 Perugia, Italy
56a
INFN Sezione di Pisa, I-56127 Pisa, Italy
56b
Dipartimento di Fisica, Università di Pisa, I-56127 Pisa, Italy
56c
Scuola Normale Superiore di Pisa, I-56127 Pisa, Italy
57
Princeton University, Princeton, New Jersey 08544, USA
58a
INFN Sezione di Roma, I-00185 Roma, Italy
58b
Dipartimento di Fisica, Università di Roma La Sapienza, I-00185 Roma, Italy
59
Universität Rostock, D-18051 Rostock, Germany
60
Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX, United Kingdom
61
CEA, Irfu, SPP, Centre de Saclay, F-91191 Gif-sur-Yvette, France
62
SLAC National Accelerator Laboratory, Stanford, California 94309 USA
63
University of South Carolina, Columbia, South Carolina 29208, USA
64
Southern Methodist University, Dallas, Texas 75275, USA
65
Stanford University, Stanford, California 94305-4060, USA
66
State University of New York, Albany, New York 12222, USA
67
Tel Aviv University, School of Physics and Astronomy, Tel Aviv 69978, Israel
68
University of Tennessee, Knoxville, Tennessee 37996, USA
69
University of Texas at Austin, Austin, Texas 78712, USA
70
University of Texas at Dallas, Richardson, Texas 75083, USA
71a
INFN Sezione di Torino, I-10125 Torino, Italy
71b
Dipartimento di Fisica, Università di Torino, I-10125 Torino, Italy
72a
INFN Sezione di Trieste, I-34127 Trieste, Italy
72b
Dipartimento di Fisica, Università di Trieste, I-34127 Trieste, Italy
73
IFIC, Universitat de Valencia-CSIC, E-46071 Valencia, Spain
74
University of Victoria, Victoria, British Columbia V8W 3P6, Canada
75
Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom
76
University of Wisconsin, Madison, Wisconsin 53706, USA
(Received 31 July 2014; published 7 January 2015)
We study the rare
B
meson decays
B

;
0
J=
ψ
K
þ
K
K

;
0
,
B

;
0
J=
ψφ
K

;
0
, and search for
B
0
J=
ψφ
, using
469
×
10
6
B
̄
B
events collected at the
Υ
ð
4
S
Þ
resonance with the
BABAR
detector at
the PEP-II
e
þ
e
asymmetric energy collider. We present new measurements of branching fractions and a
study of the
J=
ψφ
mass distribution in search of new charmonium-like states. In addition, we search for the
decay
B
0
J=
ψφ
and find no evidence of a signal.
DOI:
10.1103/PhysRevD.91.012003
PACS numbers: 13.25.Hw, 12.15.Hh, 11.30.Er
I. INTRODUCTION
Many charmonium-like resonances have been discov-
ered in the past, revealing a spectrum too rich to interpret in
terms of conventional mesons expected from potential
models
[1]
. In several cases, it has not been possible to
assign a spin-parity value to the resonance. Some of them
have been extensively investigated as possible candidates
for nonconventional mesons, such as tetraquarks, glueballs,
or hybrids
[2]
.
In a search for exotic states, the CDF experiment studied
the decay
B
þ
J=
ψφ
K
þ
[3]
, where
J=
ψ
μ
þ
μ
and
φ
ð
1020
Þ
K
þ
K
, claiming the observation of a reso-
nance labeled the
X
ð
4140
Þ
decaying to
J=
ψφ
[4]
. They
found evidence in the same decay mode for another
resonance, labeled as the
X
ð
4270
Þ
[5]
. Recently, the
LHCb experiment studied the decay
B
þ
J=
ψφ
K
þ
in
pp
collisions at 7 TeV, with a data sample more than 3
*
Deceased.
Present address: University of Tabuk, Tabuk 71491, Saudi
Arabia.
Also at Università di Perugia, Dipartimento di Fisica, Perugia,
Italy.
§
Present address: Laboratoire de Physique Nucléaire et de
Hautes Energies, IN2P3/CNRS, Paris, France.
Present address: Forschungszentrum Jülich GmbH, D-52425
Jülich, Germany.
Present address: University of Huddersfield, Huddersfield
HD1 3DH, United Kingdom.
**
Present address: University of South Alabama, Mobile,
Alabama 36688, USA.
††
Also at Università di Sassari, Sassari, Italy.
‡‡
Also at INFN Sezione di Roma, Roma, Italy.
§§
Present address: Universidad Técnica Federico Santa Maria,
Valparaiso 2390123, Chile.
STUDY OF
B

;
0
J=
ψ
K
þ
K
K

;
0
...
PHYSICAL REVIEW D
91,
012003 (2015)
012003-3
times larger than that of CDF, and set an upper limit (UL)
incompatible with the CDF result
[6]
. The D0 and the CMS
experiments more recently made studies of the same decay
channel, leading to different conclusions
[7,8]
than the
LHCb experiment. In this work we study the rare decays
B
þ
J=
ψ
K
þ
K
K
þ
,
B
0
J=
ψ
K
þ
K
K
0
S
and search for
possible resonant states in the
J=
ψφ
mass spectrum. We
also search for the decay
B
0
J=
ψφ
, which is expected to
proceed mainly via a Cabibbo-suppressed and color-
suppressed transition
̄
bd
̄
cc
̄
dd
. The absence of a signal
would indicate that the required rescattering of
̄
dd
into
̄
ss
is
very small.
This paper is organized as follows: in Sec.
II
we describe
the detector and data selection, and in Sec.
III
we report the
branching-fraction (BF) measurements. Section
IV
is
devoted to the resonance search, while Sec.
V
summarizes
the results.
II. THE
BABAR
DETECTOR AND DATA
SELECTION
We make use of the data set collected by the
BABAR
detector at the PEP-II
e
þ
e
storage rings operating at the
Υ
ð
4
S
Þ
resonance. The integrated luminosity for this analy-
sis is
422
.
5
fb
1
, which corresponds to the production of
469
×
10
6
B
̄
B
pairs
[9]
.
The
BABAR
detector is described in detail elsewhere
[10]
. We mention here only the components of the detector
that are used in the present analysis. Charged particles are
detected and their momenta measured with a combination
of a cylindrical drift chamber (DCH) and a silicon vertex
tracker (SVT), both operating within the 1.5 T magnetic
field of a superconducting solenoid. Information from a
ring-imaging Cherenkov detector (DIRC) is combined with
specific ionization measurements from the SVT and DCH
to identify charged kaon and pion candidates. The effi-
ciency for kaon identification is 90%, while the rate for a
pion being misidentified as a kaon is 2%. For low-
transverse-momentum kaon candidates that do not reach
the DIRC, particle identification relies only on the energy
loss measurement, so that the transverse momentum spec-
trum of identified kaons extends down to
150
MeV
=c
.
Electrons are identified using information provided by a
CsI(Tl) electromagnetic calorimeter (EMC), in combina-
tion with that from the SVT and DCH, while muons are
identified in the Instrumented Flux Return (IFR). This is the
outermost subdetector, in which muon/pion discrimination
is performed. Photons are detected, and their energies
measured with the EMC.
For each signal event candidate, we first reconstruct the
J=
ψ
by geometrically constraining to a common vertex a
pair of oppositely charged tracks, identified as either
electrons or muons, and apply a loose requirement that
the
χ
2
fit probability exceed 0.1%. For
J=
ψ
e
þ
e
we
use bremsstrahlung energy-loss recovery: if an electron-
associated photon cluster is found in the EMC, its
three-momentum vector is incorporated into the calculation
of the invariant mass
m
e
þ
e
. The vertex fit for a
J=
ψ
candidate includes a constraint to the nominal
J=
ψ
mass
value
[11]
.
For
B
þ
J=
ψ
K
þ
K
K
þ
candidates, we combine the
J=
ψ
candidate with three loosely identified kaons and
require a vertex-fit probability larger than 0.1%. Similarly,
for
B
0
J=
ψ
K
K
þ
K
0
S
candidates, we combine the
J=
ψ
and
K
0
S
with two loosely identified kaons and require a
vertex-fit probability larger than 0.1%.
A
K
0
S
candidate is formed by geometrically constraining
a pair of oppositely charged tracks to a common vertex,
with
χ
2
fit probability larger than 0.1%. The pion mass is
assigned to the tracks without particle identification (PID)
requirements. The three-momenta of the two pions are then
added and the
K
0
S
energy is computed using the nominal
K
0
S
mass. We require the
K
0
S
flight length significance with
respect to the
B
0
vertex to be larger than
3
σ
.
We further select
B
meson candidates using the energy
difference
Δ
E
E

B
ffiffiffi
s
p
=
2
in the center-of-mass frame
and the beam-energy-substituted mass defined as
m
ES
ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
ðð
s=
2
þ
~
p
i
·
~
p
B
Þ
=E
i
Þ
2
~
p
2
B
p
, where (
E
i
;
~
p
i
) is the initial-
state
e
þ
e
four-momentum vector in the laboratory frame
and
ffiffiffi
s
p
is the center-of-mass energy. In the above
expressions
E

B
is the
B
meson candidate energy in the
center-of-mass frame, and
~
p
B
is its laboratory frame
momentum.
When multiple candidates are present, the combination
with the smallest
Δ
E
is chosen. We find that, after requiring
m
ES
>
5
.
2
GeV
=c
2
, the fraction of events having multiple
candidates is 1.3% for
B
þ
and 8.6% for
B
0
. From
simulation, we find that 99.6% of the time we choose
the correct candidate.
The final selection requires
j
Δ
E
j
<
30
MeV and
j
Δ
E
j
<
25
MeV for
B
þ
and
B
0
decays, respectively; the additional
selection criterion
m
ES
>
5
.
2
GeV
=c
2
is required for the
calculation of the BFs, while
m
ES
>
5
.
27
GeV
=c
2
is
applied to select the signal region for the analysis of the
invariant mass systems.
III. BRANCHING FRACTIONS
Figure
1
shows the
m
ES
distributions for (a)
B
þ
J=
ψ
K
þ
K
K
þ
and (b)
B
0
J=
ψ
K
K
þ
K
0
S
candidates after
having applied the
Δ
E
selections described in Sec.
II
, while
the corresponding
Δ
E
distributions are shown in Figs.
1(c)
and
1(d)
, respectively, for
m
ES
>
5
.
27
GeV
=c
2
. Figure
2
shows the
K
þ
K
invariant mass distribution in the region
m
K
þ
K
<
1
.
1
GeV
=c
2
for (a)
B
þ
and (b)
B
0
candidates. A
clean
φ
ð
1020
Þ
signal is present in both mass spectra. The
background contributions, estimated from the
Δ
E
side-
bands in the range
40
<
j
Δ
E
j
<
70
MeV, are shown as
shaded histograms in Figs.
2(a)
and
2(b)
and are seen to be
small. In the following we have ignored the presence of
possible additional S-wave contributions in the
φ
ð
1020
Þ
signal region.
J. P. LEES
et al.
PHYSICAL REVIEW D
91,
012003 (2015)
012003-4
We select the
φ
ð
1020
Þ
signal region to be in the
mass range
½
1
.
004
1
.
034

GeV
=c
2
. Figure
2
shows the
m
ES
distribution for (c)
B
þ
J=
ψφ
K
þ
and (d)
B
0
J=
ψφ
K
0
S
candidates, respectively, for events in the
φ
mass
region, which satisfy the
Δ
E
selection criteria. Figures
2(e)
and
2(f)
show the
Δ
E
distribution for
m
ES
>
5
.
27
GeV
=c
2
,
when requiring the
K
þ
K
invariant mass to be in the
φ
ð
1020
Þ
signal region. The distributions of Figs.
2(c)
and
2(e)
contain 212 events in the
m
ES
and
Δ
E
signal
region, with an estimated background of 23 events.
Similarly, those of Figs.
2(d)
and
2(f)
contain 50 events,
with an estimated background of 9 events.
We search for the decay
B
0
J=
ψφ
by constraining a
fitted
J=
ψ
and two loosely identified kaon candidates to a
common vertex. Possible backgrounds originating from the
decay
B
0
J=
ψ
K
0

ð
892
Þ
,
K
0

ð
892
Þ
K
π
þ
, and from
the channel
B
0
J=
ψ
K
1
ð
1270
Þ
,
K
1
ð
1270
Þ
K
π
þ
π
0
,
are found to be consistent with zero, after applying a
dedicated selection as described in Secs.
II
and
III
. Figure
3
shows the corresponding
m
ES
and
Δ
E
distributions. We do
not observe a significant signal for this decay mode.
For Figs.
1
3
an unbinned maximum likelihood fit to
each
m
ES
distribution is performed to determine the yield
and obtain a BF measurement
[12]
. We use the sum of two
functions to parametrize the
m
ES
distribution; a Gaussian
function describes the signal, and an ARGUS function
[13]
the background. A study of the
Δ
E
sidebands did not
show the presence of peaking backgrounds. Table
I
sum-
marizes the fitted yields obtained.
As a validation test, we fit the
Δ
E
distributions shown in
Figs.
1
3
, using a double-Gaussian model for the signal
and a linear function for the background, and we obtain
yields consistent with those from the
m
ES
fits.
The signals in Fig.
1
, corresponding to the
B
þ
J=
ψ
K
þ
K
K
þ
and the
B
0
J=
ψ
K
þ
K
K
0
S
decays, yield
14
.
4
σ
and
5
.
5
σ
significance, respectively. Those in Fig.
2
,
which restrict the invariant mass
m
K
þ
K
to the signal region
of the
φ
ð
1020
Þ
meson, are observed with significance
16
.
1
σ
and
5
.
6
σ
, respectively. In this paper the statistical
significance of the peaks is evaluated as
ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
2
ln
ð
L
0
=L
max
Þ
p
,
where
L
max
and
L
0
represent the maximum likelihood
values with the fitted signal yield and with the signal yield
fixed to zero, respectively.
We estimate the efficiency for the different channels
using Monte Carlo (MC) simulations. For each channel we
perform full detector simulations where
B
mesons decay
uniformly over the available phase space (PHSP). These
simulated events are then reconstructed and analyzed, as
)
2
(GeV/c
ES
m
5.2
5.21
5.22
5.23 5.24
5.25
5.26
5.27
5.28
5.29
2
Events / 2 MeV/c
0
20
40
60
80
100
120
(a)
)
2
(GeV/c
ES
m
5.2
5.21
5.22
5.23 5.24
5.25
5.26
5.27
5.28
5.29
2
Events / 2 MeV/c
0
10
20
30
40
50
60
70
(b)
E (GeV)
Δ
-0.2
-0.15
-0.1
-0.05
0
0.05
0.1
0.15
0.2
Events / 5 MeV
0
10
20
30
40
50
60
70
80
90
(c)
E (GeV)
Δ
-0.2
-0.15
-0.1
-0.05
0
0.05
0.1
0.15
0.2
Events / 5 MeV
0
10
20
30
40
50
(d)
FIG. 1 (color online). The
m
ES
distributions for (a)
B
þ
J=
ψ
K
þ
K
K
þ
and (b)
B
0
J=
ψ
K
K
þ
K
0
S
, for the
Δ
E
regions indicated in
the text. The
Δ
E
distributions for
m
ES
>
5
.
27
GeV
=c
2
are shown for (c)
B
þ
J=
ψ
K
þ
K
K
þ
and (d)
B
0
J=
ψ
K
K
þ
K
0
S
. The
continuous (red) curve represents the signal plus background, while the dotted (blue) curve represents the fitted background. Vertical
(blue) lines indicate the selected signal regions.
STUDY OF
B

;
0
J=
ψ
K
þ
K
K

;
0
...
PHYSICAL REVIEW D
91,
012003 (2015)
012003-5
are the real data. These MC simulations are also used to
validate the analysis procedure and the BF extractions.
Table
I
reports the resulting integrated efficiencies for the
different channels, and the efficiency-corrected yields. The
efficiency is computed in two different ways. For
B
þ
J=
ψφ
K
þ
and
B
0
J=
ψφ
K
0
S
we make use of a Dalitz-plot-
dependent efficiency, where each event is weighted by the
inverse of the efficiency evaluated in the appropriate cell of
the Dalitz plot shown in Fig.
4
. This approach is particu-
larly important because of the lower efficiency observed at
low
J=
ψφ
invariant mass, where the spectrum deviates
from pure PHSP behavior. For the
φ
channels, the
Corrected yield
values in Table
I
are obtained as sums
of inverse Dalitz-plot efficiencies for events in the
φ
signal
regions with background subtraction taken into account as
described in Sec.
IV
. The events in the
φ
signal region
account for about 65% of the data in the four-body final
states. There is no evidence of structure in the remaining
35%
of these events, and so they are corrected according
to their average efficiency obtained from MC simulation of
four-body PHSP samples. For these channels,
B
þ
J=
ψ
K
þ
K
K
þ
and
B
0
J=
ψ
K
þ
K
K
0
S
, the PHSP cor-
rected yield is added to the
φ
signal region corrected yield
to obtain the
Corrected yield
values in lines 1 and 3 of
)
2
(GeV/c
-
K
+
K
m
0.98
1
1.02
1.04
1.06
1.08
1.1
2
Events / 2 MeV/c
0
10
20
30
40
50
60
70
(a)
)
2
(GeV/c
-
K
+
K
m
0.98
1
1.02
1.04
1.06
1.08
1.1
2
Events / 2 MeV/c
0
2
4
6
8
10
12
14
16
18
20
(b)
)
2
(GeV/c
ES
m
5.2
5.21
5.22
5.23 5.24
5.25
5.26
5.27
5.28
5.29
2
Events / 2 MeV/c
0
10
20
30
40
50
60
70
(c)
)
2
(GeV/c
ES
m
5.2
5.21
5.22
5.23 5.24
5.25
5.26
5.27
5.28
5.29
2
Events / 2 MeV/c
0
2
4
6
8
10
12
14
16
18
20
(d)
E (GeV)
Δ
-0.2
-0.15
-0.1
-0.05
0
0.05
0.1
0.15
0.2
Events / 5 MeV
0
10
20
30
40
50
60
70
(e)
E (GeV)
Δ
-0.2
-0.15
-0.1
-0.05
0
0.05
0.1
0.15
0.2
Events / 5 MeV
0
2
4
6
8
10
12
14
16
18
20
(f)
FIG. 2 (color online). (a) The
K
þ
K
mass spectrum, (c)
m
ES
, and (e)
Δ
E
distribution for
B
þ
J=
ψφ
K
þ
. (b) The
K
þ
K
mass
spectrum, (d)
m
ES
, and (f)
Δ
E
distribution for
B
0
J=
ψφ
K
0
S
. The dots are the data points, and the shaded (yellow) distributions are
obtained from the
Δ
E
sidebands. Vertical (blue) lines indicate the selected signal regions. In (a) and (b) the
m
ES
and
Δ
E
selection criteria
described in Sec.
II
have been applied.
J. P. LEES
et al.
PHYSICAL REVIEW D
91,
012003 (2015)
012003-6
Table
I
. The efficiency values in the third column of Table
I
correspond to
Event yield
divided by
Corrected yield.
Systematic uncertainties affecting the BF measurements
are listed in Table
II
. The evaluation of the integrated
luminosity is performed using the method of
B
̄
B
counting
[10]
, and we assign a uniform 0.6% uncertainty to all the
final states. The uncertainty on the efficiency evaluation
related to the size of the MC simulations is negligible with
respect to the other contributions. The systematic uncer-
tainty on the reconstruction efficiency of charged-particle
tracks is estimated from the comparison of data samples
and full detector simulations for well-chosen decay modes.
In a similar way we obtain a 1.7% systematic uncertainty in
the reconstruction of
K
0
S
meson decays. In the case of the
B
0
J=
ψφ
K
0
S
and
B
þ
J=
ψφ
K
þ
decay modes, since
the
J=
ψ
and the
φ
are vector states, we compute the
efficiency also under the assumption that the two vector
mesons are transversely or longitudinally polarized. We
consider the uncertainties related to the choice of the
probability density functions (pdf) in the fit procedure,
by varying fixed parameters by

1
σ
in their uncertainties.
We also evaluate the efficiency variations for different
charged-particle-track PID. All uncertainties are added in
quadrature. We note that the BF for
B
þ
J=
ψφ
K
þ
and
that for
B
0
J=
ψφ
K
0
are in agreement with their previous
BABAR
measurements
[14]
, which already dominate the
PDG average values
[11]
, but now we obtain more than 4
times better precision. The combination of these decay
modes was observed first by the CLEO Collaboration
[15]
.
Our BF value for the decay
B
þ
J=
ψ
K
þ
K
K
þ
is the
first measurement. For the decay
B
0
J=
ψ
K
þ
K
K
0
, the
LHCb Collaboration has obtained a BF value
ð
2
.
02

0
.
43

0
.
17

0
.
08
Þ
×
10
5
[16]
, which is consistent with
our result.
We estimate an upper limit (UL) at a 90% confidence
level (C.L.) for the BF of the decay
B
0
J=
ψφ
. The signal
yield obtained from the fit to the
m
ES
distribution is
6

4
events [Fig.
3(a)
], corresponding to an UL at 90% C.L. of
14 events. The Feldman-Cousins method
[17]
is used to
evaluate ULs on BFs. Ensembles of pseudoexperiments are
generated according to the pdfs for a given signal yield
(10000 sets of signal and background events), and fits are
performed. We obtain an UL on the
B
0
J=
ψφ
BF of
1
.
01
×
10
6
. The Belle Collaboration reported a limit of
0
.
94
×
10
6
[18]
, while a recent analysis from the LHCb
Collaboration lowers this limit to
1
.
9
×
10
7
[19]
.
We compute the ratios
R
þ
¼
B
ð
B
þ
J=
ψ
K
þ
K
K
þ
Þ
B
ð
B
þ
J=
ψφ
K
þ
Þ
¼
0
.
67

0
.
07

0
.
03
ð
1
Þ
and
R
0
¼
B
ð
B
0
J=
ψ
K
þ
K
K
0
Þ
B
ð
B
0
J=
ψφ
K
0
Þ
¼
0
.
79

0
.
20

0
.
05
;
ð
2
Þ
TABLE I. Event yields, efficiencies (
ε
) and BF measurements (
B
) for the different decay modes. For channels
involving
K
0
S
, the yields and efficiencies refer to
K
0
S
π
þ
π
, and the BF includes the corrections for
K
0
S
π
0
π
0
and
K
0
L
decay. The
B
0
J=
ψφ
UL at a 90% C.L. is listed at the end of the table.
B
channel
Event yield
ε
(%)
Corrected yield
B
10
5
)
B
þ
J=
ψ
K
þ
K
K
þ
290

22
15
.
08

0
.
04
1923

146
3
.
37

0
.
25

0
.
14
B
þ
J=
ψφ
K
þ
189

14
13
.
54

0
.
04
1396

103
5
.
00

0
.
37

0
.
15
B
0
J=
ψ
K
þ
K
K
0
68

13
10
.
35

0
.
04
657

126
3
.
49

0
.
67

0
.
15
B
0
J=
ψφ
K
0
41

710
.
10

0
.
04
406

69
4
.
43

0
.
76

0
.
19
B
0
J=
ψφ
6

431
.
12

0
.
07
19

13
<
0
.
101
)
2
(GeV/c
ES
m
5.2
5.21
5.22
5.23 5.24
5.25
5.26
5.27
5.28
5.29
2
Events / 2 MeV/c
0
1
2
3
4
5
6
7
8
9
10
(a)
E (GeV)
Δ
-0.2
-0.15
-0.1
-0.05
0
0.05
0.1
0.15
0.2
Events / 5 MeV
0
1
2
3
4
5
6
7
8
9
10
(b)
FIG. 3 (color online). (a) The
m
ES
and (b)
Δ
E
distribution for
B
0
J=
ψφ
event candidates. The curves in (a) and (b) are the result of
the fits described in the text.
STUDY OF
B

;
0
J=
ψ
K
þ
K
K

;
0
...
PHYSICAL REVIEW D
91,
012003 (2015)
012003-7
and they are consistent with being equal within the
uncertainties. We also compute the ratios
R
φ
¼
B
ð
B
0
J=
ψφ
K
0
Þ
B
ð
B
þ
J=
ψφ
K
þ
Þ
¼
0
.
89

0
.
17

0
.
04
ð
3
Þ
and
R
2
K
¼
B
ð
B
0
J=
ψ
K
þ
K
K
0
Þ
B
ð
B
þ
J=
ψ
K
þ
K
K
þ
Þ
¼
1
.
04

0
.
21

0
.
06
:
ð
4
Þ
On the basis of the simplest relevant color-suppressed
spectator quark model diagrams (e.g. Fig. 1 of Ref.
[15]
), it
would be expected that
R
þ
¼
R
0
and
R
φ
R
2
K
1
.Our
measured values of these ratios are consistent with these
expectations.
IV. SEARCH FOR RESONANCE PRODUCTION
We plot in Fig.
5(a)
the
J=
ψ
K
þ
K
mass distribution for
B
þ
J=
ψ
K
þ
K
K
þ
and in Fig.
5(b)
that for
B
0
J=
ψ
K
K
þ
K
0
S
; the signal regions are defined by the
Δ
E
selections indicated in Sec.
II
and
m
ES
>
5
.
27
GeV
=c
2
.No
prominent structure is observed in both mass spectra.
We select events in the
φ
signal regions and search for
the resonant states reported by the CDF Collaboration in
the
J=
ψφ
mass spectrum
[5]
. The mass and the width
values are fixed to
m
¼
4143
.
4
MeV
=c
2
and
Γ
¼
15
.
3
MeV for the
X
ð
4140
Þ
, and to
m
¼
4274
.
4
MeV
=c
2
and
Γ
¼
32
.
3
MeV for the
X
ð
4270
Þ
resonance. We
evaluate the mass resolution using MC simulations and
obtain
2
MeV
=c
2
resolution in the mass region between
4100
MeV
=c
2
and
4300
MeV
=c
2
. Therefore, resolution
effects can be ignored because they are much smaller than
the widths of the resonances under consideration.
We estimate the efficiency on each quasi-three-body
Dalitz plot as the ratio between the reconstructed and
generated distributions, where the values are generated
according to PHSP. Figure
4
shows the resulting distribu-
tions evaluated over the
m
2
J=
ψφ
versus
m
2
φ
K
plane for the
charged (a) and neutral (b)
B
decay, respectively. The lower
efficiency at low
J=
ψφ
mass is due to the lower
reconstruction efficiency for low kaon momentum in the
laboratory frame, as a result of energy loss in the beampipe
and SVT material.
We test the agreement between data and MC by using a
full MC simulation where the
B
þ
J=
ψφ
K
þ
and
B
0
J=
ψφ
K
0
S
decays are included with known branching
fractions. We repeat the entire analysis on these simulated
)
4
/c
2
(GeV
2
+
K
φ
m
2.5
3
3.5
4
4.5
5
)
4
/c
2
(GeV
2
φ
ψ
J/
m
17
18
19
20
21
22
23
0
0.05
0.1
0.15
0.2
0.25
(a)
)
4
/c
2
(GeV
2
+
K
φ
m
2.5
3
3.5
4
4.5
5
)
4
/c
2
(GeV
2
φ
ψ
J/
m
17
18
19
20
21
22
23
0
0.05
0.1
0.15
0.2
0.25
(b)
FIG. 4 (color online). Efficiency distribution on the Dalitz plot for (a)
B
þ
J=
ψφ
K
þ
and (b)
B
0
J=
ψφ
K
0
S
.
TABLE II. Systematic uncertainty contributions (%) to the evaluation of the BFs.
Source
B
þ
J=
ψ
K
þ
K
K
þ
B
þ
J=
ψφ
K
þ
B
0
J=
ψ
K
K
þ
K
0
S
B
0
J=
ψφ
K
0
S
B
0
J=
ψφ
B
̄
B
counting
0.6
0.6
0.6
0.6
0.6
Efficiency
0.04
0.04
0.04
0.04
0.07
Tracking
0.9
0.9
1.2
1.2
0.7
K
0
S

1.7
1.7

Secondary BFs
0.08
0.5
0.1
0.5
0.5
Decay model

0.4

0.9
1.0
pdfs
3.0
0.7
2.0
0.5
1.0
PID
2.5
2.5
3.0
3.0
2.0
Total contribution
4.1
3.0
4.2
4.4
2.7
J. P. LEES
et al.
PHYSICAL REVIEW D
91,
012003 (2015)
012003-8
data and find good agreement between generated and
reconstructed branching fractions. Resolution effects are
small and are computed using MC simulations. We obtain
average values of 2.9 MeV for (
J=
ψφ
) and 2.2 MeV for
(
J=
ψ
K
). These small values do not produce bias in the
evaluation of the efficiency and the measurement of the
branching fractions.
To search for the two resonances in the
J=
ψφ
mass
distributions, we perform unbinned maximum likelihood
fits to the
B
J=
ψφ
K
decay Dalitz plots. We model the
resonances using S-wave relativistic Breit-Wigner (BW)
functions with parameters fixed to the CDF values. The
nonresonant contributions are represented by a constant
term, and no interference is allowed between the fit
components. We estimate the background contributions
from the
Δ
E
sidebands, find them to be small and
consistent with a PHSP behavior, and so in the fits they
are incorporated into the nonresonant PHSP term. The
decay of a pseudoscalar meson to two vector states may
contain high spin contributions which could generate
nonuniform angular distributions. However, due to the
limited data sample we do not include such angular terms,
and we assume that the resonances decay isotropically. The
amplitudes are normalized using PHSP MC-generated
events with
B
parameters obtained from the fits to the
data. The fit functions are weighted by the two-dimensional
efficiency computed on the Dalitz plots.
We perform fits separately for the charged
B
þ
sample
and the combined
B
þ
and
B
0
samples. Due to the very
limited statistics of the
B
0
sample we do not perform a
separate fit, but instead subtract the fit result for the
B
þ
sample from that for the combined
B
þ
and
B
0
sample. In
this case we make use of the two different efficiencies for
the two channels. In the MC simulation performed, we
make use of a weighted mean of the two efficiencies
evaluated on the respective Dalitz plots.
Table
III
summarizes the results of the fits. We report the
background-corrected fit fractions for the two resonances,
f
X
ð
4140
Þ
and
f
X
ð
4270
Þ
, the two-dimensional (2D)
χ
2
com-
puted on the Dalitz plot, and the one-dimensional (1D)
χ
2
computed on the
J=
ψφ
mass projection. For this purpose,
we use an adaptive binning method and divide the Dalitz
plot into a number of cells in such a way that the minimum
expected population per cell is not smaller than 7. We
generate MC simulations weighted by the efficiency and by
the results from the fits. These are normalized to the event
yield in data, using the same bin definitions. We then
compute the
χ
2
¼
P
N
cells
i
¼
1
ð
N
i
obs
N
i
exp
Þ
2
=N
i
exp
, where
N
i
obs
)
2
(GeV/c
-
K
+
K
ψ
J/
m
4.2
4.3
4.4
4.5
4.6
4.7
2
Combinations / 10 MeV/c
0
5
10
15
20
25
30
(a)
)
2
(GeV/c
-
K
+
K
ψ
J/
m
4.2
4.3
4.4
4.5
4.6
4.7
2
Combinations / 10 MeV/c
0
2
4
6
8
10
12
14
16
(b)
FIG. 5 (color online). Invariant mass distribution
J=
ψ
K
þ
K
for (a)
B
þ
J=
ψ
K
þ
K
K
þ
and (b)
B
0
J=
ψ
K
þ
K
K
0
S
. The shaded
(yellow) histogram on each figure indicates the background estimated from the
Δ
E
sidebands.
2
)
2
(GeV/c
2
φ
ψ
J/
m
17
18
19
20
21
22
23
2
)
2
Events / 0.16 (GeV/c
0
5
10
15
20
25
(a)
2
)
2
(GeV/c
2
+
K
φ
m
2.5
3
3.5
4
4.5
5
2
)
2
Events / 0.07 (GeV/c
0
5
10
15
20
25
(b)
2
)
2
(GeV/c
2
+
K
ψ
J/
m
13
14
15
16
17
18
2
)
2
Events / 0.15 (GeV/c
0
5
10
15
20
25
(c)
FIG. 6 (color online). Dalitz plot projections for
B
þ
J=
ψφ
K
þ
on (a)
m
2
J=
ψφ
, (b)
m
2
φ
K
þ
, and (c)
m
2
J=
ψ
K
þ
. The continuous (red) curves
are the results from fit model A performed including the
X
ð
4140
Þ
and
X
ð
4270
Þ
resonances. The dashed (blue) curve in (a) indicates the
projection for fit model D, with no resonances. The shaded (yellow) histograms indicate the background estimated from the
Δ
E
sidebands.
STUDY OF
B

;
0
J=
ψ
K
þ
K
K

;
0
...
PHYSICAL REVIEW D
91,
012003 (2015)
012003-9