Observation of new resonances decaying to
D
and
D
in inclusive
e
þ
e
collisions near
ffiffiffi
s
p
¼
10
:
58 GeV
P. del Amo Sanchez,
1
J. P. Lees,
1
V. Poireau,
1
E. Prencipe,
1
V. Tisserand,
1
J. Garra Tico,
2
E. Grauges,
2
M. Martinelli,
3a,3b
A. Palano,
3a,3b
M. Pappagallo,
3a,3b
G. Eigen,
4
B. Stugu,
4
L. Sun,
4
M. Battaglia,
5
D. N. Brown,
5
B. Hooberman,
5
L. T. Kerth,
5
Yu. G. Kolomensky,
5
G. Lynch,
5
I. L. Osipenkov,
5
T. Tanabe,
5
C. M. Hawkes,
6
A. T. Watson,
6
H. Koch,
7
T. Schroeder,
7
D. J. Asgeirsson,
8
C. Hearty,
8
T. S. Mattison,
8
J. A. McKenna,
8
A. Khan,
9
A. Randle-Conde,
9
V. E. Blinov,
10
A. R. Buzykaev,
10
V. P. Druzhinin,
10
V. B. Golubev,
10
A. P. Onuchin,
10
S. I. Serednyakov,
10
Yu. I. Skovpen,
10
E. P. Solodov,
10
K. Yu. Todyshev,
10
A. N. Yushkov,
10
M. Bondioli,
11
S. Curry,
11
D. Kirkby,
11
A. J. Lankford,
11
M. Mandelkern,
11
E. C. Martin,
11
D. P. Stoker,
11
H. Atmacan,
12
J. W. Gary,
12
F. Liu,
12
O. Long,
12
G. M. Vitug,
12
C. Campagnari,
13
T. M. Hong,
13
D. Kovalskyi,
13
J. D. Richman,
13
C. West,
13
A. M. Eisner,
14
C. A. Heusch,
14
J. Kroseberg,
14
W. S. Lockman,
14
A. J. Martinez,
14
T. Schalk,
14
B. A. Schumm,
14
A. Seiden,
14
L. O. Winstrom,
14
C. H. Cheng,
15
D. A. Doll,
15
B. Echenard,
15
D. G. Hitlin,
15
P. Ongmongkolkul,
15
F. C. Porter,
15
A. Y. Rakitin,
15
R. Andreassen,
16
M. S. Dubrovin,
16
G. Mancinelli,
16
B. T. Meadows,
16
M. D. Sokoloff,
16
P. C. Bloom,
17
W. T. Ford,
17
A. Gaz,
17
M. Nagel,
17
U. Nauenberg,
17
J. G. Smith,
17
S. R. Wagner,
17
R. Ayad,
18,
*
W. H. Toki,
18
H. Jasper,
19
T. M. Karbach,
19
J. Merkel,
19
A. Petzold,
19
B. Spaan,
19
K. Wacker,
19
M. J. Kobel,
20
K. R. Schubert,
20
R. Schwierz,
20
D. Bernard,
21
M. Verderi,
21
P. J. Clark,
22
S. Playfer,
22
J. E. Watson,
22
M. Andreotti,
23a,23b
D. Bettoni,
23a
C. Bozzi,
23a
R. Calabrese,
23a,23b
A. Cecchi,
23a,23b
G. Cibinetto,
23a,23b
E. Fioravanti,
23a,23b
P. Franchini,
23a,23b
E. Luppi,
23a,23b
M. Munerato,
23a,23b
M. Negrini,
23a,23b
A. Petrella,
23a,23b
L. Piemontese,
23a
R. Baldini-Ferroli,
24
A. Calcaterra,
24
R. de Sangro,
24
G. Finocchiaro,
24
M. Nicolaci,
24
S. Pacetti,
24
P. Patteri,
24
I. M. Peruzzi,
24,
†
M. Piccolo,
24
M. Rama,
24
A. Zallo,
24
R. Contri,
25a,25b
E. Guido,
25a,25b
M. Lo Vetere,
25a,25b
M. R. Monge,
25a,25b
S. Passaggio,
25a
C. Patrignani,
25a,25b
E. Robutti,
25a
S. Tosi,
25a,25b
B. Bhuyan,
26
V. Prasad,
26
C. L. Lee,
27
M. Morii,
27
A. Adametz,
28
J. Marks,
28
U. Uwer,
28
F. U. Bernlochner,
29
M. Ebert,
29
H. M. Lacker,
29
T. Lueck,
29
A. Volk,
29
P. D. Dauncey,
30
M. Tibbetts,
30
P. K. Behera,
31
U. Mallik,
31
C. Chen,
32
J. Cochran,
32
H. B. Crawley,
32
L. Dong,
32
W. T. Meyer,
32
S. Prell,
32
E. I. Rosenberg,
32
A. E. Rubin,
32
A. V. Gritsan,
33
Z. J. Guo,
33
N. Arnaud,
34
M. Davier,
34
D. Derkach,
34
J. Firmino da Costa,
34
G. Grosdidier,
34
F. Le Diberder,
34
A. M. Lutz,
34
B. Malaescu,
34
A. Perez,
34
P. Roudeau,
34
M. H. Schune,
34
J. Serrano,
34
V. Sordini,
34,
‡
A. Stocchi,
34
L. Wang,
34
G. Wormser,
34
D. J. Lange,
35
D. M. Wright,
35
I. Bingham,
36
C. A. Chavez,
36
J. P. Coleman,
36
J. R. Fry,
36
E. Gabathuler,
36
R. Gamet,
36
D. E. Hutchcroft,
36
D. J. Payne,
36
C. Touramanis,
36
A. J. Bevan,
37
F. Di Lodovico,
37
R. Sacco,
37
M. Sigamani,
37
G. Cowan,
38
S. Paramesvaran,
38
A. C. Wren,
38
D. N. Brown,
39
C. L. Davis,
39
A. G. Denig,
40
M. Fritsch,
40
W. Gradl,
40
A. Hafner,
40
K. E. Alwyn,
41
D. Bailey,
41
R. J. Barlow,
41
G. Jackson,
41
G. D. Lafferty,
41
J. Anderson,
42
R. Cenci,
42
A. Jawahery,
42
D. A. Roberts,
42
G. Simi,
42
J. M. Tuggle,
42
C. Dallapiccola,
43
E. Salvati,
43
R. Cowan,
44
D. Dujmic,
44
G. Sciolla,
44
M. Zhao,
44
D. Lindemann,
45
P. M. Patel,
45
S. H. Robertson,
45
M. Schram,
45
P. Biassoni,
46a,46b
A. Lazzaro,
46a,46b
V. Lombardo,
46a
F. Palombo,
46a,46b
S. Stracka,
46a,46b
L. Cremaldi,
47
R. Godang,
47,
x
R. Kroeger,
47
P. Sonnek,
47
D. J. Summers,
47
X. Nguyen,
48
M. Simard,
48
P. Taras,
48
G. De Nardo,
49a,49b
D. Monorchio,
49a,49b
G. Onorato,
49a,49b
C. Sciacca,
49a,49b
G. Raven,
50
H. L. Snoek,
50
C. P. Jessop,
51
K. J. Knoepfel,
51
J. M. LoSecco,
51
W. F. Wang,
51
L. A. Corwin,
52
K. Honscheid,
52
R. Kass,
52
J. P. Morris,
52
N. L. Blount,
53
J. Brau,
53
R. Frey,
53
O. Igonkina,
53
J. A. Kolb,
53
R. Rahmat,
53
N. B. Sinev,
53
D. Strom,
53
J. Strube,
53
E. Torrence,
53
G. Castelli,
54a,54b
E. Feltresi,
54a,54b
N. Gagliardi,
54a,54b
M. Margoni,
54a,54b
M. Morandin,
54a
M. Posocco,
54a
M. Rotondo,
54a
F. Simonetto,
54a,54b
R. Stroili,
54a,54b
E. Ben-Haim,
55
G. R. Bonneaud,
55
H. Briand,
55
G. Calderini,
55
J. Chauveau,
55
O. Hamon,
55
Ph. Leruste,
55
G. Marchiori,
55
J. Ocariz,
55
J. Prendki,
55
S. Sitt,
55
M. Biasini,
56a,56b
E. Manoni,
56a,56b
A. Rossi,
56a,56b
C. Angelini,
57a,57b
G. Batignani,
57a,57b
S. Bettarini,
57a,57b
M. Carpinelli,
57a,57b,
k
G. Casarosa,
57a,57b
A. Cervelli,
57a,57b
F. Forti,
57a,57b
M. A. Giorgi,
57a,57b
A. Lusiani,
57a,57c
N. Neri,
57a,57b
E. Paoloni,
57a,57b
G. Rizzo,
57a,57b
J. J. Walsh,
57a
D. Lopes Pegna,
58
C. Lu,
58
J. Olsen,
58
A. J. S. Smith,
58
A. V. Telnov,
58
F. Anulli,
59a
E. Baracchini,
59a,59b
G. Cavoto,
59a
R. Faccini,
59a,59b
F. Ferrarotto,
59a
F. Ferroni,
59a,59b
M. Gaspero,
59a,59b
L. Li Gioi,
59a
M. A. Mazzoni,
59a
G. Piredda,
59a
F. Renga,
59a,59b
T. Hartmann,
60
T. Leddig,
60
H. Schro
̈
der,
60
R. Waldi,
60
T. Adye,
61
B. Franek,
61
E. O. Olaiya,
61
F. F. Wilson,
61
S. Emery,
62
G. Hamel de Monchenault,
62
G. Vasseur,
62
Ch. Ye
`
che,
62
M. Zito,
62
M. T. Allen,
63
D. Aston,
63
D. J. Bard,
63
R. Bartoldus,
63
J. F. Benitez,
63
C. Cartaro,
63
M. R. Convery,
63
J. Dorfan,
63
G. P. Dubois-Felsmann,
63
W. Dunwoodie,
63
R. C. Field,
63
M. Franco Sevilla,
63
B. G. Fulsom,
63
A. M. Gabareen,
63
M. T. Graham,
63
P. Grenier,
63
C. Hast,
63
W. R. Innes,
63
M. H. Kelsey,
63
H. Kim,
63
P. Kim,
63
M. L. Kocian,
63
D. W. G. S. Leith,
63
S. Li,
63
B. Lindquist,
63
S. Luitz,
63
V. Luth,
63
H. L. Lynch,
63
D. B. MacFarlane,
63
H. Marsiske,
63
D. R. Muller,
63
H. Neal,
63
S. Nelson,
63
C. P. O’Grady,
63
I. Ofte,
63
M. Perl,
63
T. Pulliam,
63
B. N. Ratcliff,
63
A. Roodman,
63
PHYSICAL REVIEW D
82,
111101(R) (2010)
RAPID COMMUNICATIONS
1550-7998
=
2010
=
82(11)
=
111101(9)
111101-1
Ó
2010 The American Physical Society
A. A. Salnikov,
63
V. Santoro,
63
R. H. Schindler,
63
J. Schwiening,
63
A. Snyder,
63
D. Su,
63
M. K. Sullivan,
63
S. Sun,
63
K. Suzuki,
63
J. M. Thompson,
63
J. Va’vra,
63
A. P. Wagner,
63
M. Weaver,
63
C. A. West,
63
W. J. Wisniewski,
63
M. Wittgen,
63
D. H. Wright,
63
H. W. Wulsin,
63
A. K. Yarritu,
63
C. C. Young,
63
V. Ziegler,
63
X. R. Chen,
64
W. Park,
64
M. V. Purohit,
64
R. M. White,
64
J. R. Wilson,
64
S. J. Sekula,
65
M. Bellis,
66
P. R. Burchat,
66
A. J. Edwards,
66
T. S. Miyashita,
66
S. Ahmed,
67
M. S. Alam,
67
J. A. Ernst,
67
B. Pan,
67
M. A. Saeed,
67
S. B. Zain,
67
N. Guttman,
68
A. Soffer,
68
P. Lund,
69
S. M. Spanier,
69
R. Eckmann,
70
J. L. Ritchie,
70
A. M. Ruland,
70
C. J. Schilling,
70
R. F. Schwitters,
70
B. C. Wray,
70
J. M. Izen,
71
X. C. Lou,
71
F. Bianchi,
72a,72b
D. Gamba,
72a,72b
M. Pelliccioni,
72a,72b
M. Bomben,
73a,73b
L. Lanceri,
73a,73b
L. Vitale,
73a,73b
N. Lopez-March,
74
F. Martinez-Vidal,
74
D. A. Milanes,
74
A. Oyanguren,
74
J. Albert,
75
Sw. Banerjee,
75
H. H. F. Choi,
75
K. Hamano,
75
G. J. King,
75
R. Kowalewski,
75
M. J. Lewczuk,
75
I. M. Nugent,
75
J. M. Roney,
75
R. J. Sobie,
75
T. J. Gershon,
76
P. F. Harrison,
76
T. E. Latham,
76
E. M. T. Puccio,
76
H. R. Band,
77
S. Dasu,
77
K. T. Flood,
77
Y. Pan,
77
R. Prepost,
77
C. O. Vuosalo,
77
and S. L. Wu
77
(
B
A
B
AR
Collaboration)
1
Laboratoire d’Annecy-le-Vieux de Physique des Particules (LAPP), Universite
́
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, 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 British Columbia, Vancouver, British Columbia, Canada V6T 1Z1
9
Brunel University, Uxbridge, Middlesex UB8 3PH, United Kingdom
10
Budker Institute of Nuclear Physics, Novosibirsk 630090, Russia
11
University of California at Irvine, Irvine, California 92697, USA
12
University of California at Riverside, Riverside, California 92521, USA
13
University of California at Santa Barbara, Santa Barbara, California 93106, USA
14
University of California at Santa Cruz, Institute for Particle Physics, Santa Cruz, California 95064, USA
15
California Institute of Technology, Pasadena, California 91125, USA
16
University of Cincinnati, Cincinnati, Ohio 45221, USA
17
University of Colorado, Boulder, Colorado 80309, USA
18
Colorado State University, Fort Collins, Colorado 80523, USA
19
Technische Universita
̈
t Dortmund, Fakulta
̈
t Physik, D-44221 Dortmund, Germany
20
Technische Universita
̈
t Dresden, Institut fu
̈
r Kern- und Teilchenphysik, D-01062 Dresden, Germany
21
Laboratoire Leprince-Ringuet, CNRS/IN2P3, Ecole Polytechnique, F-91128 Palaiseau, France
22
University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom
23a
INFN Sezione di Ferrara, I-44100 Ferrara, Italy
23b
Dipartimento di Fisica, Universita
`
di Ferrara, I-44100 Ferrara, Italy
24
INFN Laboratori Nazionali di Frascati, I-00044 Frascati, Italy
25a
INFN Sezione di Genova, I-16146 Genova, Italy
25b
Dipartimento di Fisica, Universita
`
di Genova, I-16146 Genova, Italy
26
Indian Institute of Technology Guwahati, Guwahati, Assam, 781 039, India
27
Harvard University, Cambridge, Massachusetts 02138, USA
28
Universita
̈
t Heidelberg, Physikalisches Institut, Philosophenweg 12, D-69120 Heidelberg, Germany
29
Humboldt-Universita
̈
t zu Berlin, Institut fu
̈
r Physik, Newtonstr. 15, D-12489 Berlin, Germany
30
Imperial College London, London, SW7 2AZ, United Kingdom
31
University of Iowa, Iowa City, Iowa 52242, USA
32
Iowa State University, Ames, Iowa 50011-3160, USA
33
Johns Hopkins University, Baltimore, Maryland 21218, USA
34
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
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
P. DEL AMO SANCHEZ
et al.
PHYSICAL REVIEW D
82,
111101(R) (2010)
RAPID COMMUNICATIONS
111101-2
39
University of Louisville, Louisville, Kentucky 40292, USA
40
Johannes Gutenberg-Universita
̈
t Mainz, Institut fu
̈
r Kernphysik, D-55099 Mainz, Germany
41
University of Manchester, Manchester M13 9PL, United Kingdom
42
University of Maryland, College Park, Maryland 20742, USA
43
University of Massachusetts, Amherst, Massachusetts 01003, USA
44
Massachusetts Institute of Technology, Laboratory for Nuclear Science, Cambridge, Massachusetts 02139, USA
45
McGill University, Montre
́
al, Que
́
bec, Canada H3A 2T8
46a
INFN Sezione di Milano, I-20133 Milano, Italy
46b
Dipartimento di Fisica, Universita
`
di Milano, I-20133 Milano, Italy
47
University of Mississippi, University, Mississippi 38677, USA
48
Universite
́
de Montre
́
al, Physique des Particules, Montre
́
al, Que
́
bec, Canada H3C 3J7
49a
INFN Sezione di Napoli, I-80126 Napoli, Italy
49b
Dipartimento di Scienze Fisiche, Universita
`
di Napoli Federico II, I-80126 Napoli, Italy
50
NIKHEF, National Institute for Nuclear Physics and High Energy Physics, NL-1009 DB Amsterdam, The Netherlands
51
University of Notre Dame, Notre Dame, Indiana 46556, USA
52
Ohio State University, Columbus, Ohio 43210, USA
53
University of Oregon, Eugene, Oregon 97403, USA
54a
INFN Sezione di Padova, I-35131 Padova, Italy
54b
Dipartimento di Fisica, Universita
`
di Padova, I-35131 Padova, Italy
55
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
56a
INFN Sezione di Perugia, I-06100 Perugia, Italy
56b
Dipartimento di Fisica, Universita
`
di Perugia, I-06100 Perugia, Italy
57a
INFN Sezione di Pisa, I-56127 Pisa, Italy
57b
Dipartimento di Fisica, Universita
`
di Pisa, I-56127 Pisa, Italy
57c
Scuola Normale Superiore di Pisa, I-56127 Pisa, Italy
58
Princeton University, Princeton, New Jersey 08544, USA
59a
INFN Sezione di Roma, I-00185 Roma, Italy
59b
Dipartimento di Fisica, Universita
`
di Roma La Sapienza, I-00185 Roma, Italy
60
Universita
̈
t Rostock, D-18051 Rostock, Germany
61
Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, OX11 0QX, United Kingdom
62
CEA, Irfu, SPP, Centre de Saclay, F-91191 Gif-sur-Yvette, France
63
SLAC National Accelerator Laboratory, Stanford, California 94309 USA
64
University of South Carolina, Columbia, South Carolina 29208, USA
65
Southern Methodist University, Dallas, Texas 75275, USA
66
Stanford University, Stanford, California 94305-4060, USA
67
State University of New York, Albany, New York 12222, USA
68
Tel Aviv University, School of Physics and Astronomy, Tel Aviv, 69978, Israel
69
University of Tennessee, Knoxville, Tennessee 37996, USA
70
University of Texas at Austin, Austin, Texas 78712, USA
71
University of Texas at Dallas, Richardson, Texas 75083, USA
72a
INFN Sezione di Torino, I-10125 Torino, Italy
72b
Dipartimento di Fisica Sperimentale, Universita
`
di Torino, I-10125 Torino, Italy
73a
INFN Sezione di Trieste, I-34127 Trieste, Italy
73b
Dipartimento di Fisica, Universita
`
di Trieste, I-34127 Trieste, Italy
74
IFIC, Universitat de Valencia-CSIC, E-46071 Valencia, Spain
75
University of Victoria, Victoria, British Columbia, Canada V8W 3P6
76
Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom
77
University of Wisconsin, Madison, Wisconsin 53706, USA
(Received 12 September 2010; published 1 December 2010)
We present a study of the
D
þ
,
D
0
þ
, and
D
þ
systems in inclusive
e
þ
e
!
c
c
interactions in a
search for new excited
D
meson states. We use a data set, consisting of
454 fb
1
, collected at center-of-
mass energies near 10.58 GeV by the
B
A
B
AR
detector at the SLAC PEP-II asymmetric-energy collider. We
*
Now at Temple University, Philadelphia, PA 19122, USA
†
Also with Universita
`
di Perugia, Dipartimento di Fisica, Perugia, Italy
‡
Also with Universita
`
di Roma La Sapienza, I-00185 Roma, Italy
x
Now at University of South AL, Mobile, AL 36688, USA
k
Also with Universita
`
di Sassari, Sassari, Italy
OBSERVATION OF NEW RESONANCES DECAYING TO
...
PHYSICAL REVIEW D
82,
111101(R) (2010)
RAPID COMMUNICATIONS
111101-3
observe, for the first time, candidates for the radial excitations of the
D
0
,
D
0
, and
D
þ
, as well as the
L
¼
2
excited states of the
D
0
and
D
þ
, where
L
is the orbital angular momentum of the quarks.
DOI:
10.1103/PhysRevD.82.111101
PACS numbers: 14.40.Lb, 12.38.
t, 13.25.Ft
The spectrum of mesons consisting of a charm and an up
or a down quark is poorly known. The spectrum of quark-
antiquark systems was predicted in 1985 using a relativistic
chromodynamic potential model [
1
]. The low-mass spec-
trum of the
c
u
or
c
d
system is comprised of the ground
states (1S), the orbital excitations with angular momentum
L
¼
1
;
2
(1P, 1D), and the first radial excitations (2S).
In this paper we label the states using the notation
D
ð
2
S
þ
1
Þ
J
ð
nL
Þ
, where
J
is the total angular momentum of
the state,
n
is the radial quantum number, and
L
and
S
are
the orbital angular momentum and total spin of the quarks.
Besides the ground states
ð
D;D
Þ
, only two 1P states,
known as the
D
1
ð
2420
Þ
and
D
2
ð
2460
Þ
[
2
], are well-
established experimentally since they have relatively
narrow widths (
30 MeV
). In contrast, the other two 1P
states, known as the
D
0
ð
2400
Þ
and
D
0
1
ð
2430
Þ
, are very
broad (
300 MeV
), making them difficult to detect [
3
–
5
].
To search for states not yet observed, we analyze the
inclusive
production of the
D
þ
,
D
0
þ
, and
D
þ
[
6
]
final states in the reaction
e
þ
e
!
c
c
!
D
ðÞ
X
, where
X
is any additional system. We use an event sample consist-
ing of approximately
590
10
6
e
þ
e
!
c
c
events
(
454 fb
1
) produced at
e
þ
e
center-of-mass (CM) ener-
gies near 10.58 GeVand collected with the
B
A
B
AR
detector
at the SLAC PEP-II asymmetric-energy collider. Our sig-
nal yield for the
L
¼
1
resonances is more than 10 times
larger than the best previous study [
7
], resulting in much
greater sensitivity to higher resonances.
The
B
A
B
AR
detector is described in detail in Ref. [
8
].
Charged-particle momenta are measured with a five-layer,
double-sided silicon vertex tracker (SVT) and a 40-layer
drift chamber (DCH) inside a 1.5-T superconducting sole-
noidal magnet. A calorimeter consisting of 6580 CsI(Tl)
crystals is used to measure electromagnetic energy. A ring-
imaging Cherenkov radiation detector (DIRC), aided by
measurements of ionization energy loss,
dE=dx
, in the
SVT and DCH, is used for particle identification (PID) of
charged hadrons.
The
D
system is reconstructed in the neutral
D
þ
and charged
D
0
þ
modes, where
D
þ
!
K
þ
þ
and
D
0
!
K
þ
. A PID algorithm is applied to all tracks.
Charged kaon identification has an average efficiency of
90% within the acceptance of the detector and an
average pion-to-kaon misidentification probability of
1.5%.
For all channels we perform a vertex fit for the
D
þ
and
D
0
daughters. To improve the signal-to-background
ratio for
D
þ
!
K
þ
þ
, we require that the measured
flight distance of the
D
þ
candidate from the
e
þ
e
inter-
action region be greater than 5 times its uncertainty.
To improve the signal purity for
D
0
!
K
þ
we require
cos
K
>
0
:
9
, where
K
is the angle formed by the
K
in
the
D
0
candidate rest frame with respect to the prior
direction of the
D
0
candidate in the CM reference frame.
The
D
candidates for both
D
þ
and
D
0
are then recon-
structed by performing a vertex fit with an additional
charged
primary
pion, which originates from the
e
þ
e
interaction region. For all vertex fits we require a
2
probability
>
0
:
1%
.
In the
D
0
þ
sample, we veto
D
0
candidates from
D
þ
or
D
0
decays by forming
D
0
þ
(where the
þ
is any addi-
tional pion in the event) and
D
0
0
combinations, and
rejecting the event if the invariant-mass difference between
this combination and the
D
0
candidate is within
2
of the
nominal
D
-
D
mass difference [
2
], where
is the detector
resolution.
The
K
þ
þ
and
K
þ
mass distributions are shown
in Figs.
1(a)
and
1(b)
. We fit these distributions to a linear
background and a Gaussian signal; the signal widths ob-
tained are
D
þ
¼
6
:
7 MeV
=c
2
and
D
0
¼
7
:
6 MeV
=c
2
.
The signal region is defined to be within
2
:
5
of the
peak, while sideband regions are defined as the ranges
ð
5
:
0
;
7
:
5
Þ
and
ð
4
:
0
;
6
:
5
Þ
for the
D
þ
and
D
0
, respectively. The
D
þ
signal region has purity
N
S
=
ð
N
S
þ
N
B
Þ¼
65%
, where
N
S
(
N
B
) is the number of
signal (background) events, while the
D
0
purity is 83%.
The
D
þ
system is reconstructed using the
D
0
!
K
þ
and
D
0
!
K
þ
þ
decay modes. A
D
0
)
2
) (GeV/c
+
π
+
π
-
m(K
1.82
1.84 1.86 1.88
1.9
1.92
2
Entries / 1 MeV/c
0
50
100
150
200
1000
×
a)
)
2
) (GeV/c
+
π
-
m(K
1.82
1.84
1.86
1.88
1.9
2
Entries / 1 MeV/c
0
100
200
300
400
1000
×
b)
)
2
candidate mass (GeV/c
0
D
1.8
1.82 1.84 1.86 1.88 1.9
1.92
2
Entries / 1 MeV/c
0
20
40
60
80
1000
×
c)
)
2
) (GeV/c
0
) - m(D
+
π
0
m(D
0.14 0.142 0.144 0.146 0.148 0.15 0.152
2
Entries / 0.1 MeV/c
0
100
200
1000
×
d)
FIG. 1 (color online). Mass distribution for (a)
D
þ
and (b)
D
0
candidates in the
D
þ
and
D
0
þ
samples. Plots (c) and
(d) correspond to the
D
þ
sample and show the mass distri-
bution for
D
0
candidates and the
m
distribution for
D
þ
candidates. The vertical lines show the signal and, in (a) and
(b), the sideband regions.
P. DEL AMO SANCHEZ
et al.
PHYSICAL REVIEW D
82,
111101(R) (2010)
RAPID COMMUNICATIONS
111101-4
candidate is accepted if its invariant mass is within
30 MeV
=c
2
of the mean value. A
D
þ
candidate is
reconstructed by requiring an additional slow pion (
þ
s
)
originating from the
e
þ
e
interaction region. We select
a
D
þ
candidate if the mass difference
m
¼
m
ð
K
þ
ð
þ
Þ
þ
s
Þ
m
ð
K
þ
ð
þ
ÞÞ
is within
2
:
0 MeV
=c
2
of the mean value. The
D
0
candidate
invariant-mass distribution and the
m
distribution are
shown in Figs.
1(c)
and
1(d)
. The
D
þ
signal purity is
89%. Finally, we reconstruct a
D
þ
candidate by com-
bining a
D
þ
candidate with an additional charged track
identified as a
and applying a vertex fit.
Background from
e
þ
e
!
B
B
events, and much of the
combinatorial background, are removed by requiring the
CM momentum of the
D
ðÞ
system to be greater than
3
:
0 GeV
=c
. In addition, we remove fake primary pion
candidates originating mainly from the opposite side of
the event by requiring
cos
>
0
:
8
. The angle
is
defined in the
D
ðÞ
rest frame as the angle between the
primary pion direction and the prior direction of the
D
ðÞ
system in the CM frame.
To extract the resonance parameters we define the var-
iables
M
ð
D
þ
Þ¼
m
ð
K
þ
þ
Þ
m
ð
K
þ
þ
Þþ
m
D
þ
and
M
ð
D
0
þ
Þ¼
m
ð
K
þ
þ
Þ
m
ð
K
þ
Þþ
m
D
0
, where
m
D
þ
and
m
D
0
are the values of the
D
þ
and
D
0
mass [
2
]. The use of the mass difference improves the
resolution on the reconstructed mass to about
3 MeV
=c
2
.
We remove the contribution due to fake
D
þ
and
D
0
can-
didates by subtracting the
M
ð
D
Þ
distributions obtained by
selecting events in the
D
þ
or
D
0
candidate mass sidebands.
The
D
þ
and
D
0
þ
mass spectra are presented in
Fig.
2
and show similar features.
(i) Prominent peaks for
D
2
ð
2460
Þ
0
and
D
2
ð
2460
Þ
þ
.
(ii) The
D
þ
mass spectrum shows a peaking back-
ground (feeddown) at about
2
:
3 GeV
=c
2
due to
decays from the
D
1
ð
2420
Þ
0
and
D
2
ð
2460
Þ
0
to
D
þ
. The
D
þ
in these events decays to
D
þ
0
and the
0
is missing in the reconstruction. The
missing
0
has very low momentum because the
D
þ
decay is very close to threshold. Therefore,
these decays have a mass resolution of only
5
:
8 MeV
=c
2
and a bias of
143
:
2 MeV
=c
2
.
Similarly,
D
0
þ
shows peaking backgrounds due
to the decays of the
D
1
ð
2420
Þ
þ
and
D
2
ð
2460
Þ
þ
to
D
0
þ
, where the
D
0
decays to
D
0
0
.
(iii) Both
D
þ
and
D
0
þ
mass distributions show
new structures around 2.6 and
2
:
75 GeV
=c
2
.We
call these enhancements
D
ð
2600
Þ
and
D
ð
2760
Þ
.
We have compared these mass spectra with those ob-
tained from generic
e
þ
e
!
cc
Monte Carlo (MC) events.
These events were generated using
JETSET
[
9
] with all the
known particle resonances incorporated. The events are
then reconstructed using a detailed GEANT4 [
10
] detector
simulation and the event selection procedure used for the
data. In addition, we study
D
mass spectra from the
D
þ
and
D
0
candidate mass sidebands, as well as mass spectra
for wrong-sign
D
þ
þ
and
D
0
samples. We find no
backgrounds or reflections that can cause the structures at
2.6 and
2
:
76 GeV
=c
2
. In the study of the
D
0
þ
final state
we find a peaking background due to events where the
D
0
candidate is not a true
D
0
, but the
K
candidate and the
primary
þ
candidate are from a true
D
0
!
K
þ
decay.
These combinations produce enhancements in
M
ð
D
0
þ
Þ
both in the
D
0
candidate mass signal region and sidebands.
However, we find this background to be linear as a function
of the
D
0
candidate mass, and it is removed by the sideband
subtraction.
The smooth background is modeled using the function
B
ð
x
Þ¼
P
ð
x
Þ
e
c
1
x
þ
c
2
x
2
for
x
x
0
e
d
0
þ
d
1
x
þ
d
2
x
2
for
x>x
0
;
(1)
where
P
ð
x
Þ
1
2
x
ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
½
x
2
ð
m
D
þ
m
Þ
2
½
x
2
ð
m
D
m
Þ
2
p
is a two-body phase-space factor and
x
¼
M
ð
D
Þ
. Only
four parameters are free in the piecewise exponential:
c
1
,
c
2
,
d
2
, and
x
0
. The parameters
d
0
and
d
1
are fixed by
)
2
) (GeV/c
-
π
+
M(D
2.2
2.4
2.6
2.8
3
3.2
)
2
Events / (0.005 GeV/c
0
5
10
15
20
25
1000
×
)
2
) (GeV/c
-
π
+
M(D
2.2
2.4
2.6
2.8
3
3.2
)
2
Events / (0.005 GeV/c
0
5
10
15
20
25
1000
×
2.4
2.5
2.6
2.7
2.8
0
1
2
3
4
2.4
2.5
2.6
2.7
2.8
0
1
2
3
4
Fit A
)
2
) (GeV/c
+
π
0
M(D
2.2
2.4
2.6
2.8
3
3.2
)
2
Events / (0.005 GeV/c
0
5
10
15
20
25
1000
×
)
2
) (GeV/c
+
π
0
M(D
2.2
2.4
2.6
2.8
3
3.2
)
2
Events / (0.005 GeV/c
0
5
10
15
20
25
1000
×
2.4
2.5
2.6
2.7
2.8
0
1
2
2.4
2.5
2.6
2.7
2.8
0
1
2
Fit B
FIG. 2 (color online). Mass distribution for
D
þ
(top) and
D
0
þ
(bottom) candidates. Points correspond to data, with the
total fit overlaid as a solid curve. The dotted curves are the signal
components. The lower solid curves correspond to the smooth
combinatoric background and to the peaking backgrounds at
2
:
3 GeV
=c
2
. The inset plots show the distributions after sub-
traction of the combinatoric background.
OBSERVATION OF NEW RESONANCES DECAYING TO
...
PHYSICAL REVIEW D
82,
111101(R) (2010)
RAPID COMMUNICATIONS
111101-5
requiring that
B
ð
x
Þ
be continuous and differentiable at the
transition point
x
0
. We account for the feeddown of peak-
ing backgrounds by convolving Breit-Wigner (BW) func-
tions [
11
] with a function describing the resolution and bias
obtained from the simulation of these decays. The mass
and width of the
D
1
ð
2420
Þ
feeddown are fixed to the values
obtained in the
D
þ
analysis described below, while the
parameters of the
D
2
ð
2460
Þ
feeddown are fixed to those of
the true
D
2
ð
2460
Þ
in the same
M
ð
D
Þ
distribution.
The
D
2
ð
2460
Þ
is modeled using a relativistic BW func-
tion with the appropriate Blatt-Weisskopf centrifugal bar-
rier factor [
2
]. The
D
ð
2600
Þ
and
D
ð
2760
Þ
are modeled
with relativistic BW functions [
2
]. Finally, although not
visible in the
M
ð
D
þ
Þ
mass distribution, we include
a BW function to account for the known resonance
D
0
ð
2400
Þ
, which is expected to decay to this final state.
The
2
per number of degrees of freedom (NDF) of the fit
decreases from
596
=
245
to
281
=
242
when this resonance is
included. This resonance is very broad and is present
together with the feeddown and
D
2
ð
2460
Þ
0
; therefore we
restrict its mass and width parameters to be within
2
of
the known values [
5
]. The shapes of the signal components
are corrected for a small variation of the efficiency as a
function of
M
ð
D
Þ
and are multiplied by the two-body
phase-space factor. They are also corrected for the mass
resolution by convolving them with the resolution function
determined from MC simulation of signal decays. The
fit to the
M
ð
D
þ
Þ
distribution (fit A) is shown in Fig.
2
(top). The results of this fit, as well as fits to the other final
states described below, are shown in Table
I
. In this table,
we show the significance for each new signal, defined as
the signal yield divided by the total uncertainty on the
yield.
The fit to the
D
0
þ
mass spectrum is similar to that
described for the
D
þ
system. Because the feeddown is
larger and the statistical precision of the resonances is not
as good as for
D
þ
, we fix the width parameters of all
resonances to the values determined from
D
þ
assuming
isospin symmetry. The fit to the
M
ð
D
0
þ
Þ
mass distribu-
tion (fit B) is shown in Fig.
2
(bottom); this fit has
2
=
NDF
of
278
=
224
. We find consistent mass values for both
D
ð
2600
Þ
and
D
ð
2760
Þ
in the fits of the
D
þ
and
D
0
þ
mass distributions.
We now search for these new states in the
D
þ
decay
mode. We define the variable
M
ð
D
þ
Þ¼
m
ð
K
þ
ð
þ
Þ
þ
s
Þ
m
ð
K
þ
ð
þ
Þ
þ
s
Þþ
m
D
þ
where
m
D
þ
is the value of the
D
þ
mass [
2
]. The
D
þ
mass distribution is shown in Fig.
3
and shows the
following features:
(i) Prominent
D
1
ð
2420
Þ
0
and
D
2
ð
2460
Þ
0
peaks.
(ii) Two additional enhancements at
2
:
60 GeV
=c
2
and
2
:
75 GeV
=c
2
, which we initially denote as
D
ð
2600
Þ
0
and
D
ð
2750
Þ
0
.
Studies of the generic MC simulation as well as studies of
the
D
þ
sidebands and the wrong-sign sample (
D
þ
þ
)
show no peaking backgrounds in this mass spectrum.
We fit
M
ð
D
þ
Þ
by parametrizing the background
with the function in Eq. (
1
). The
D
1
ð
2420
Þ
0
and
D
2
ð
2460
Þ
0
resonances are modeled using relativistic BW
functions with appropriate Blatt-Weisskopf form factors.
The
D
ð
2600
Þ
0
and
D
ð
2750
Þ
0
are modeled with relativistic
BW functions. The broad resonance
D
0
1
ð
2430
Þ
0
is known to
decay to this final state, however, this fit is insensitive to it
due to its large width (
380 MeV
)[
4
] and because the
background parameters are free.
TABLE I. Summary of the results. The first error is statistical and the second is systematic; ‘‘fixed’’ indicates the parameters were
fixed to the values from fit A or C. The significance is defined as the yield divided by its total error.
Resonance
Channel (fit) Efficiency (%)
Yield (
10
3
)
Mass (
MeV
=c
2
)
Width (MeV)
Significance
D
1
ð
2420
Þ
0
D
þ
(C)
102
:
8
1
:
3
2
:
3 2420
:
1
0
:
1
0
:
831
:
4
0
:
5
1
:
3
D
þ
(E)
1
:
09
0
:
03
214
:
6
1
:
2
6
:
4
2420.1 (fixed)
31.4 (fixed)
D
2
ð
2460
Þ
0
D
þ
(A)
1
:
29
0
:
03
242
:
8
1
:
8
3
:
4 2462
:
2
0
:
1
0
:
850
:
5
0
:
6
0
:
7
D
þ
(E)
1
:
12
0
:
04
136
2
13
2462.2 (fixed)
50.5 (fixed)
D
ð
2550
Þ
0
D
þ
(C)
34
:
3
6
:
7
9
:
2
2539
:
4
4
:
5
6
:
8
130
12
13
3
:
0
D
þ
(E)
1
:
14
0
:
04
98
:
4
8
:
2
38
2539.4 (fixed)
130 (fixed)
D
ð
2600
Þ
0
D
þ
(A)
1
:
35
0
:
05
26
:
0
1
:
4
6
:
6
2608
:
7
2
:
4
2
:
593
6
13
3
:
9
D
þ
(D)
50
:
2
3
:
0
6
:
7
2608.7 (fixed)
93 (fixed)
7
:
3
D
þ
(E)
1
:
18
0
:
05
71
:
4
1
:
7
7
:
3
2608.7 (fixed)
93 (fixed)
D
ð
2750
Þ
0
D
þ
(E)
1
:
23
0
:
07
23
:
5
2
:
1
5
:
2
2752
:
4
1
:
7
2
:
771
6
11
4
:
2
D
ð
2760
Þ
0
D
þ
(A)
1
:
41
0
:
09
11
:
3
0
:
8
1
:
0
2763
:
3
2
:
3
2
:
360
:
9
5
:
1
3
:
68
:
9
D
2
ð
2460
Þ
þ
D
0
þ
(B)
110
:
8
1
:
3
7
:
5 2465
:
4
0
:
2
1
:
1
50.5 (fixed)
D
ð
2600
Þ
þ
D
0
þ
(B)
13
:
0
1
:
3
4
:
5
2621
:
3
3
:
7
4
:
2
93 (fixed)
2
:
8
D
ð
2760
Þ
þ
D
0
þ
(B)
5
:
7
0
:
7
1
:
5
2769
:
7
3
:
8
1
:
5
60.9 (fixed)
3
:
5
P. DEL AMO SANCHEZ
et al.
PHYSICAL REVIEW D
82,
111101(R) (2010)
RAPID COMMUNICATIONS
111101-6
Because of the vector nature of the
D
þ
, the
D
þ
final state contains additional information about the spin-
parity (
J
P
) quantum numbers of the resonances. In the rest
frame of the
D
þ
, we define the
helicity
angle
H
as the
angle between the primary pion
and the slow pion
þ
from the
D
þ
decay. The distributions in
cos
H
for the
predicted resonances, assuming parity conservation, are
given in Table
II
. Initially, we have attempted to fit the
M
ð
D
þ
Þ
distribution incorporating only two new sig-
nals at
2
:
6 GeV
=c
2
and at
2
:
75 GeV
=c
2
. However,
when we extract the yields as a function of
cos
H
we
find that the mean value of the peak at
2
:
6 GeV
=c
2
increases by
70 MeV
=c
2
between
cos
H
¼
1
and
cos
H
¼
0
, and decreases again as
cos
H
!þ
1
. This
behavior suggests two resonances with different helicity-
angle distributions are present in this mass region. To
proceed we incorporate a new component, which we call
D
ð
2550
Þ
0
, into our model at
2
:
55 GeV
=c
2
. We extract
the parameters of this component by requiring
j
cos
H
j
>
0
:
75
in order to suppress the other resonances. In this fit
(fit C), shown in Fig.
3
(top), we fix the parameters of the
D
2
ð
2460
Þ
0
and
D
ð
2600
Þ
0
to those measured in
D
þ
.We
obtain a
2
=
NDF
of
214
=
205
for this fit. This fit also
determines the parameters of the
D
1
ð
2420
Þ
0
. We then
perform a complementary fit (fit D), shown in Fig.
3
(middle), in which we require
j
cos
H
j
<
0
:
5
to discrimi-
nate in favor of the
D
ð
2600
Þ
0
. We obtain a
2
=
NDF
of
210
=
209
for this fit. To determine the final parameters of
the
D
ð
2750
Þ
0
signal we fit the total
D
þ
sample while
fixing the parameters of all other BW components to the
values determined in the previous fits. This final fit (fit E),
shown in Fig.
3
(bottom), has a
2
=
NDF
of
244
=
207
.
Systematic uncertainties on all fit results are estimated
by varying the parameters that were fixed in the fits and by
varying the bin width and mass range of the histograms. In
addition, the BW shape used for the new signals is replaced
by that for a
D
-wave decay, and we vary the background
model according to deviations observed when this model is
used to fit the smooth distribution in the wrong-sign
samples. A systematic uncertainty is also estimated from
a possible contribution of the
D
0
1
ð
2430
Þ
. Finally, we esti-
mate uncertainties on the mass values due to uncertainties
in the magnetic field and the SVT material density. Effects
due to possible interference between the decay amplitudes
for different excited states and the background amplitudes
are ignored in this inclusive analysis.
The final model for the
M
ð
D
þ
Þ
distribution is used
to extract the signal yields as a function of
cos
H
.We
divide the data into 10 subsamples corresponding to
cos
H
intervals of 0.2 between
1
and
þ
1
. Each sample is fitted
with all shape parameters fixed to the values determined
above. The yields extracted from these fits are plotted for
each signal in Fig.
4
. For the
D
1
ð
2420
Þ
we measure the
2.2
2.4
2.6
2.8
3
3.2
)
2
Events / ( 0.005 GeV/c
2
4
6
8
10
12
14
16
18
1000
×
2.2
2.4
2.6
2.8
3
3.2
)
2
Events / ( 0.005 GeV/c
2
4
6
8
10
12
14
16
18
1000
×
2.4
2.5
2.6
2.7
2.8
0
0.5
1
1.5
2
2.5
2.4
2.5
2.6
2.7
2.8
0
0.5
1
1.5
2
2.5
Fit C
2.2
2.4
2.6
2.8
3
3.2
)
2
Events / ( 0.005 GeV/c
2
4
6
8
10
12
14
16
18
2.2
2.4
2.6
2.8
3
3.2
)
2
Events / ( 0.005 GeV/c
2
4
6
8
10
12
14
16
18
2.4
2.5
2.6
2.7
2.8
0
1
2
3
4
5
2.4
2.5
2.6
2.7
2.8
0
1
2
3
4
5
Fit D
)
2
) (GeV/c
-
π
*+
M(D
2.2
2.4
2.6
2.8
3
3.2
)
2
Events / ( 0.005 GeV/c
5
10
15
20
25
30
35
40
45
)
2
) (GeV/c
-
π
*+
M(D
2.2
2.4
2.6
2.8
3
3.2
)
2
Events / ( 0.005 GeV/c
5
10
15
20
25
30
35
40
45
2.4
2.5
2.6
2.7
2.8
0
2
4
6
8
10
2.4
2.5
2.6
2.7
2.8
0
2
4
6
8
10
Fit E
FIG. 3 (color online). Mass distributions for
D
þ
candi-
dates. Top: candidates with
j
cos
H
j
>
0
:
75
. Middle: candidates
with
j
cos
H
j
<
0
:
5
. Bottom: all candidates. Points correspond to
data, with the total fit overlaid as a solid curve. The lower solid
curve is the combinatoric background, and the dotted curves are
the signal components. The inset plots show the distributions
after subtraction of the combinatoric background.
TABLE II. Properties of the predicted states [
1
]. The value of
the parameter
h
depends on the state.
State
Predicted mass
J
P
cos
H
distribution
D
1
0
ð
2S
Þ
2
:
58 GeV
=c
2
0
/
cos
2
H
D
3
1
ð
2S
Þ
2
:
64 GeV
=c
2
1
/
sin
2
H
D
1
1
ð
1P
Þ
2
:
44 GeV
=c
2
1
þ
/
1
þ
h
cos
2
H
D
3
0
ð
1P
Þ
2
:
40 GeV
=c
2
0
þ
Decay not allowed
D
3
1
ð
1P
Þ
2
:
49 GeV
=c
2
1
þ
/
1
þ
h
cos
2
H
D
3
2
ð
1P
Þ
2
:
50 GeV
=c
2
2
þ
/
sin
2
H
D
1
2
ð
1D
Þ
2
:
83 GeV
=c
2
2
/
1
þ
h
cos
2
H
D
3
1
ð
1D
Þ
2
:
82 GeV
=c
2
1
/
sin
2
H
D
3
2
ð
1D
Þ
2
:
83 GeV
=c
2
2
/
1
þ
h
cos
2
H
D
3
3
ð
1D
Þ
2
:
83 GeV
=c
2
3
/
sin
2
H
OBSERVATION OF NEW RESONANCES DECAYING TO
...
PHYSICAL REVIEW D
82,
111101(R) (2010)
RAPID COMMUNICATIONS
111101-7
helicity parameter
h
¼
5
:
72
0
:
25
, where the error in-
cludes both statistical and systematic uncertainties. This
value is consistent with the measurement by ZEUS [
12
].
The
cos
H
distributions of the
D
2
ð
2460
Þ
and
D
ð
2600
Þ
are
consistent with the expectations for
natural parity
, defined
by
P
¼ð
1
Þ
J
, and leading to a
sin
2
H
distribution. This
observation supports the assumption that the enhancement
assigned to the
D
ð
2600
Þ
in the
D
þ
and
D
þ
belong
to the same state; only states with natural parity can decay
to both
D
þ
and
D
þ
. The
cos
H
distribution for the
D
ð
2550
Þ
0
is consistent with pure
cos
2
H
as expected for a
J
P
¼
0
state.
The ratio of branching fractions
B
ð
D
!
D
þ
Þ
B
ð
D
!
D
þ
Þ
(where
D
labels any resonance) can be useful in the identification
of the new signals with predicted states. We compute this
ratio for the
D
2
ð
2460
Þ
0
,
D
ð
2600
Þ
0
, and
D
ð
2750
Þ
0
using
the yields obtained from the fits to the total samples
and correcting for the reconstruction efficiency:
ð
N
D
="
D
Þ
=
ð
N
D
="
D
Þ
. The efficiencies and yields are
shown in Table
I
. We find the following ratios:
B
ð
D
2
ð
2460
Þ
0
!
D
þ
Þ
B
ð
D
2
ð
2460
Þ
0
!
D
þ
Þ
¼
1
:
47
0
:
03
0
:
16
;
B
ð
D
ð
2600
Þ
0
!
D
þ
Þ
B
ð
D
ð
2600
Þ
0
!
D
þ
Þ
¼
0
:
32
0
:
02
0
:
09
;
B
ð
D
ð
2760
Þ
0
!
D
þ
Þ
B
ð
D
ð
2750
Þ
0
!
D
þ
Þ
¼
0
:
42
0
:
05
0
:
11
:
The first uncertainty is due to the statistical uncertainty on
the yields. The second uncertainty includes the systematic
uncertainty on the yields, the systematic uncertainty due to
differences in PID and tracking efficiency, and the errors
from the branching fractions for the decay chains [
2
].
Although in the last ratio the signal in the numerator may
not be the same as the signal in the denominator, we
determine the ratio, as it may help elucidate the nature of
this structure.
In summary, we have analyzed the inclusive production
of the
D
þ
,
D
0
þ
, and
D
þ
systems in search of new
D
-meson resonances using
454 fb
1
of data collected by
the
B
A
B
AR
experiment. We observe for the first time
four signals, which we denote
D
ð
2550
Þ
0
,
D
ð
2600
Þ
0
,
D
ð
2750
Þ
0
, and
D
ð
2760
Þ
0
. We also observe the isospin
partners
D
ð
2600
Þ
þ
and
D
ð
2760
Þ
þ
. The
D
ð
2550
Þ
0
and
D
ð
2600
Þ
0
have mass values and
cos
H
distributions that
are consistent with the predicted radial excitations
D
1
0
ð
2
S
Þ
and
D
3
1
ð
2
S
Þ
. The
D
ð
2760
Þ
0
signal observed in
D
þ
is
very close in mass to the
D
ð
2750
Þ
0
signal observed in
D
þ
; however, their mass and width values differ by
2
:
6
and
1
:
5
, respectively. Four
L
¼
2
states are pre-
dicted to lie in this region [
1
], but only two are expected to
decay to
D
þ
. This may explain the observed features.
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
B
A
B
AR
. 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), MES (Russia), MICIIN (Spain), and STFC
(United Kingdom). Individuals have received support from
the Marie Curie EIF (European Union), the A. P. Sloan
Foundation (USA), and the Binational Science Foundation
(USA-Israel).
[1] S. Godfrey and N. Isgur,
Phys. Rev. D
32
, 189 (1985)
.
[2] C. Amsler
et al.
(Particle Data Group),
Phys. Lett. B
667
,1
(2008)
.
[3] A. F. Falk and M. E. Peskin,
Phys. Rev. D
49
, 3320
(1994)
.
[4] K. Abe
et al.
(Belle Collaboration),
Phys. Rev. D
69
,
112002 (2004)
.
[5] B. Aubert
et al.
(
B
A
B
AR
Collaboration),
Phys. Rev. D
79
,
112004 (2009)
.
[6] Charge conjugates are implied throughout this paper.
H
θ
cos
-1
-0.5
0
0.5
1
Signal Yield / 0.2
0
20
40
1000
×
0.25)
±
[1+(5.72
∝
Y
H
ε
)]
H
θ
(
2
cos
×
(2420)
1
D
H
θ
cos
-1
-0.5
0
0.5
1
Signal Yield / 0.2
0
10
20
1000
×
H
ε
)
H
θ
(
2
sin
∝
Y
(2460)
2
*
D
H
θ
cos
-1
-0.5
0
0.5
1
Signal Yield / 0.2
0
10
20
1000
×
H
ε
)
H
θ
(
2
cos
∝
Y
D(2550)
H
θ
cos
-1
-0.5
0
0.5
1
Signal Yield / 0.2
0
5
10
1000
×
H
ε
)
H
θ
(
2
sin
∝
Y
D (2600)
*
H
θ
cos
-1
-0.5
0
0.5
1
Signal Yield / 0.2
0
1
2
3
1000
×
0.28)
±
[1-(0.33
∝
Y
H
ε
)]
H
θ
(
2
cos
×
D(2750)
FIG. 4 (color online). Distribution in
cos
H
for each signal in
D
þ
. The error bars include statistical and correlated systematic
uncertainties. The curve is a fit using the function
Y
shown in the plot;
"
H
is the efficiency as a function of
cos
H
.
P. DEL AMO SANCHEZ
et al.
PHYSICAL REVIEW D
82,
111101(R) (2010)
RAPID COMMUNICATIONS
111101-8