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The New Narrow “Ds” States – A minireview
Frank Porter
Caltech
(From the BaBar Collaboration)
Results from:
BaBar (abstract 395, PRL 90 (2003) 242001, A. Palano PIC)
Belle (abstract 570, R. Chistov & K. Trabelsi FPCP 2003)
CLEO (abstract 813, hep-ex/0305100, submitted to PRD,
J. Urheim CIPANP)
CDF (M. Shapiro FPCP 2003)
Two new narrow states (names from presumed quantum numbers, qq̄
model):D∗
sJ(2317)±
DsJ(2460)±1 Frank Porter, 17 July 2003, International Europhysics Conference on High Energy Physics
The Ds Level Scheme
Light quark angular momentum (j), combined with heavy quark spin.
P -wave multiplet
Spin-Orbit Tensor Force
= 0 ...l
= 1l
= 2 ...l
= 1/2j
= 3/2j
+ = 0PJ
+ = 1PJ
+ = 1PJ
+ = 2PJ
3× 2 ×2 states
2×2
4×2 states
1
3
3
5 states
mixing
)2M
ass
(GeV
/c
2
2.2
2.4
2.6
2.8
3
–0 –1 +0 +1 +2 –3 =PJ
DK
K*D
Godfrey/Isgur (1985)Di Pierro/Eichten (2001)ObservedNewly Discovered
Figures: Courtesy of David Williams
Conventional wisdom: P -wave j = 1/2 states heavy enough for isospin-
allowed strong decays to produce large widths. E.g., D∗±s0 → D0K±.
2 Frank Porter, 17 July 2003, International Europhysics Conference on High Energy Physics
The New Narrow State at 2317 MeV in M(Dsπ0)
Mass peak consistent with experimental resolution. Hence Γ < several MeV.
BaBarDs → φπ Ds → K∗Kπ
Ds → KKππ0
Belle preliminary
0
50
100
150
200
250
300
350
0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6
M(Ds π0) - M(Ds)GeV/c
2GeV/c
2
Eve
nts
/5M
eV
π sideband0
D sidebands
CLEO
2.10 2.20 2.30 2.40 2.50 2.60M(Dsπ
0) (GeV/c2)
0
40
80E
vent
s/5M
eV/c
2
80
Data
qq Monte Carlo
(a)
3 Frank Porter, 17 July 2003, International Europhysics Conference on High Energy Physics
Isospin of State at M = 2317 MeV
Narrow decay width suggests isospin violating decay, I �= 1.
Not seen in D±s π∓, D±
s π±, hence I = 0.
CDF preliminary
]2
Candidates [GeV/c+
πφMass of
1.9 1.92 1.94 1.96 1.98 2 2.02
2N
umbe
r of
Can
dida
tes/
2 M
eV/c
0
500
1000
1500
2000
2500
3000
CDF Run II Preliminary
2RMS: 7.6 MeV/c
-1 ~80 pb’ss+Signal Window: 24600 D
2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3N
umbe
r of
Ent
ries
/ 10
MeV
0
50
100
150
200
250
300
-πs+
D
+πs+
D
CDF Run II Preliminary-1 ~80 pb) > 350 MeV/cπ(tp
2317
M(D ) candidate (GeV)s π
Sensitivity estimated with D∗2 → Dπ modes, relative Ds:D rates.
Working to further quantify using DsJ(2573) → DK for normalization.
4 Frank Porter, 17 July 2003, International Europhysics Conference on High Energy Physics
D∗sJ(2317)± Spin-Parity
D∗sJ(2317) → Dsπ
0. If parity conserved, then natural JP (hence ∗).BaBar
D∗sJ(2317) → Dsπ
0 helicity angle
distribution consistent with uni-
form; consistent with 0+, or with
isotropic polarization.
Not seen in Dsπ+π− or Dsπ
0π0, which are forbidden for 0+:
CLEO
0.30 0.35 0.40 0.45 0.50 0.550
4
8
12
Eve
nts/
2M
eV/c
2
2317
M(D ) (GeV))-M(Ds s
+ -ππ
BaBar
π πM(D ) (GeV)00s
CDF preliminary
2.25 2.3 2.35 2.4 2.45 2.5N
umbe
r of E
ntri
es /
10
MeV
0
20
40
60
80
100
120
140
160
-π+πs+
D
-π-πs+
D
C DF R un II P reliminary-1 ~80 pb
+π+πs+
D
> 350 MeV/ct
Minimum P ion p
2317
ππ) (GeV)sM(D
5 Frank Porter, 17 July 2003, International Europhysics Conference on High Energy Physics
D∗sJ(2317)± Spin-Parity (continued)
If D∗sJ(2317) is spin zero,
then decay to Dsγ is for-
bidden. Not seen.
Belle preliminary B → DDsγ
0
0
2.2 2.3 2.4 2.5 2.
(c)
M(Ds ) (GeV)γ
2
23172317
CLEO
0.00 0.10 0.20 0.30 0.40 0.50 0.60M(Dsγ)-M(Ds) (GeV/c2)
101
102
103
Eve
nts/
5MeV
/c2 (a)2317
BaBar
Look forward to angular analysis in B → DD∗sJ (2317) decays.
6 Frank Porter, 17 July 2003, International Europhysics Conference on High Energy Physics
Observation of D∗sJ(2317) in Exclusive B → DDsπ
0 Decays(Belle preliminary, 124 × 106BB̄, D+
s → φπ+, K̄∗0K+, K0SK+)
0
10
20 (a)
0-0.1-0.2 0.1 0.2
Eve
nts
/10
Me
V
E (GeV)∆
0
10
20 (a)
2.2 2.3 2.4 2.5 2.6
Events
/10 M
eV
M(D ) (GeV)s
0π
B Decay channel Yield (∆E) B(10−4)
D̄0D∗sJ(2317), D∗
sJ(2317) → Dsπ0 13.7+5.1
−4.5 8.1+3.0−2.7 ± 2.4
D̄−D∗sJ(2317), D∗
sJ(2317) → Dsπ0 10.3+3.9
−3.1 8.6+3.3−2.6 ± 2.6
D̄0D∗sJ(2317), D∗
sJ(2317) → Dsγ 3.4+2.8−2.2 2.4+2.0
−1.5(< 5.7)
D̄−D∗sJ(2317), D∗
sJ(2317) → Dsγ 2.3+2.5−1.9 2.6+2.8
−2.2(< 7.1)
cf (RPP 2002): B+ → D̄0D+s = (1.3 ± 0.4)%, B0 → D−D+
s = (0.8 ± 0.3)%;
B+ → D̄0D∗+s = (0.9 ± 0.4)%, B0 → D−D∗+
s = (1.0 ± 0.5)% .
7 Frank Porter, 17 July 2003, International Europhysics Conference on High Energy Physics
D∗sJ(2317)± Summary
Quantity BaBar Belle CLEO
Dataset (fb−1) 91 87 13.5
Ds Modes φπ, K∗K φπ φπ
Mass (MeV) 2316.8 ± 0.4 ± 3 2317.2 ± 0.5 ± 0.9 2318.5 ± 1.2 ± 1.1
M(2317) − M(Ds) (MeV) 348.4 ± 0.4 ± 3 348.7 ± 0.5 ± 0.7 350.0 ± 1.2 ± 1.0
Width (MeV, 90% C.L.) < 10 † < 7
B(Dsπ+π−)/B(Dsπ
0) (90% C.L.) < 0.019B(Dsγ)/B(Dsπ
0) (90% C.L.) < 0.05 < 0.052B(D∗
sπ0)/B(Dsπ
0) (90% C.L.) < 0.11B(D∗
sγ)/B(Dsπ0) (90% C.L.) < 0.059
σ·B(D∗sJ→Dsπ
0)σ(Ds)
(p > 3.5 GeV) (7.9 ± 1.2 ± 0.4) × 10−2
† σ = 7.6 ± 0.5 MeV consistent with resolution.
I = 0 favored (Narrow width to Dsπ0, CDF search in Dsπ
±)
JP natural, consistent with 0+
8 Frank Porter, 17 July 2003, International Europhysics Conference on High Energy Physics
The New Narrow State at 2460 MeV in Dsπ0γ
Mass peak consistent with experimental resolution. Hence Γ < several MeV.
CLEO(a)
(b)
M(Dsγπ0) - M(Dsγ) (GeV/c2)
Eve
nts
/ 5 M
eV/c
2
0
10
20
0
10
20
0.1 0.2 0.3 0.4 0.5 0.6
D*
D*
s
s
region
sideband region
Belle preliminary
0
20
40
60
80
100
0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6
M(Ds* π0) - M(Ds*)GeV/c
2
Eve
nts
/5M
eV D
regions*
sidebandπ0
BaBar
preliminary
D
regions
sD sideband*
*
9 Frank Porter, 17 July 2003, International Europhysics Conference on High Energy Physics
Reflection (Cross-feed) Ambiguity
∆M(DsJ(2460)−D∗s(2112)) ∼ ∆M(D∗
sJ(2317)−Ds) ∼ 350 MeV
→ Feed-up of D∗sJ(2317) to DsJ(2460) peak possible by adding a ran-
dom photon consistent with D∗s(2112) → Dsγ.
→ Feed-down of DsJ(2460) to D∗sJ(2317) peak possible by neglecting
the photon in the D∗s(2112) → Dsγ transition.
⇒ Ambiguity in DsJ(2460) decays: Is it DsJ(2460) → D∗s(2112)π0
or DsJ(2460) → D∗sJ(2317)γ?
BaBar/Belle/CLEO all correct for cross-feeds under the DsJ(2460) → D∗s(2112)π0 hy-
pothesis.
10 Frank Porter, 17 July 2003, International Europhysics Conference on High Energy Physics
Study of Cross-feed Ambiguity (BaBar preliminary)Dsπ
0γ: The M(Dsγ) vs M(Dsπ0) scatter plot.2460 boundary
Data Monte Carlo
Projections with linear background subtraction:Is it DsJ(2460) → D∗
s(2112)π0? Is it DsJ(2460) → D∗sJ(2317)γ?
Conclusion: Much better fit to DsJ (2460) → D∗s(2112)π0
11 Frank Porter, 17 July 2003, International Europhysics Conference on High Energy Physics
DsJ(2460) Spin-Parity
Observed in DsJ(2460) → Dsγ, hence J �= 0.
0
5
10
15
20
25
30
35
40
45
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8M(Ds γ) - M(Ds)
GeV/c2
Eve
nts
/5M
eV
Belle preliminary; Continuum
No DsJ(2317) seen (forbidden for spin 0)
N(DsJ(2460) → Dsγ) = 152 ± 18 ± 11
Rules out J = 0
Helicity angle in DsJ(2460) → D∗s(2112)π0, D∗
s(2112)π0 → Dsγ (BaBar preliminary)Inconsistent with JP = 0−. [nb: no prediction for 1+, 2−.]
D (2460)
D (2112)*s
sJ
s
0
D
.
γθ
π
12 Frank Porter, 17 July 2003, International Europhysics Conference on High Energy Physics
Angular analysis in B → DDsJ(2460) → DDsγ (Belle preliminary)
0
0
2.2 2.3 2.4 2.5 2.
(c)
M(Ds ) (GeV)γ
2 B → DDsγ
B(B → DDsJ(2460) → DDsγ)
=(6.7+1.3
−1.2 ± 2.0) × 10−4
B(DsJ (2460) → Dsγ)
B(DsJ (2460) → D∗sπ
0)= 0.38 ± 0.11 ± 0.04
0
2
4
6
8
10
12
-1 -0.5 0 0.5 1
cos(θDsγ)
Eve
nts
B → DDsJ (2460) → DDsγ
Data = points with errorsSpin 1 = histogram; Spin 2 = dashed line.Consistent with sin2 θ, as expected for 1+
13 Frank Porter, 17 July 2003, International Europhysics Conference on High Energy Physics
Observation in Exclusive B Decays (Belle preliminary)
124 × 106BB̄
B → DD(∗)sJ , D → Kπ, Kππ, Kπππ, Ds → φπ, K̄∗0K+, K0
SK+
0
10
20 (a)
0
10
(b)
0
10
20
-0.2 -0.1 0 0.1 0.2
(c)
∆E (GeV)
Events/(0.01 GeV)
0
10
20 (a)
0
10
20 (b)
0
20
2.2 2.3 2.4 2.5 2.6
(c)
M(DsJ) (GeV/c2)
Events/(0.01 GeV)
M(DM(D
M(DM(D
M(DM(D
*
s )
0π
γ
s
s
π0)
)
14 Frank Porter, 17 July 2003, International Europhysics Conference on High Energy Physics
Exclusive B Decays (Belle preliminary)
B Decay channel Yield (∆E) B(10−4)
D̄0DsJ(2460), DsJ(2460) → D∗sπ
0 7.2+3.7−3.0 11.9+6.1
−4.9 ± 3.6
D−DsJ(2460), DsJ(2460) → D∗sπ
0 11.8+3.8−3.2 22.7+7.3
−6.2 ± 6.8
D̄0DsJ(2460), DsJ(2460) → Dsγ 19.1+5.6−5.0 5.6+1.6
−1.5 ± 1.7
D−DsJ(2460), DsJ(2460) → Dsγ 18.5+5.0−4.3 8.4+2.4
−2.2 ± 2.5
D̄0DsJ(2460), DsJ(2460) → D∗sγ 4.4+3.8
−3.3 3.1+2.7−2.3(< 7.5)
D−DsJ(2460), DsJ(2460) → D∗sγ 1.1+1.8
−1.2 1.3+2.0−1.4(< 4.6)
D̄0DsJ(2460), DsJ(2460) → Dsπ0 < 2.4 < 2.2
D−DsJ(2460), DsJ(2460) → Dsπ0 < 2.4 < 2.8
D̄0DsJ(2460), DsJ(2460) → Dsπ+π− < 4.0 < 2.4
D−DsJ(2460), DsJ(2460) → Dsπ+π− < 2.5 < 2.0
15 Frank Porter, 17 July 2003, International Europhysics Conference on High Energy Physics
DsJ(2460) Summary
Quantity BaBar Belle CLEO
Dataset (fb−1) 91 87 13.5
N(D∗sπ
0, D∗s → Dsγ) 127 ± 22 126 ± 25 ± 24 41 ± 12
Mass (MeV) 2457.0 ± 1.4 ± 3 2456.5 ± 1.3 ± 1.1 2463.6 ± 1.7 ± 1.2
M(2460) − M(D∗s) (MeV) 344.6 ± 1.2 ± 3 344.1 ± 1.3 ± 0.9 351.2 ± 1.7 ± 1.0
Width (MeV, 90% C.L.) † † < 7B(Dsπ
+π−)B(D∗
sπ0) (90% C.L.) < 0.08B(Dsγ)B(D∗
sπ0) (90% C.L.) 0.63 ± 0.15 ± 0.15 < 0.49B(D∗
sγ)B(D∗
sπ0) (90% C.L.) < 0.16B(DsJ (2317)∗γ)
B(D∗sπ0) (90% C.L.) < 0.58
† Width of mass peak is consistent with resolution.
JP �= 0±, consistent with 1+.
Not seen in Dsπ±, Dsπ
+π− modes in CDF. Not seen in Dsπ+π− in B decays in Belle.
16 Frank Porter, 17 July 2003, International Europhysics Conference on High Energy Physics
Production Rates (pCM > 3.5 GeV)CLEOσ·B(D∗+
sJ →D+s γ)
σ(D+s )
= 0.59 ± 0.03 ± 0.01
σ·B(D∗sJ(2317)+→D+
s π0)σ(D+
s )= (7.9 ± 1.2 ± 0.4) × 10−2
σ·B(DsJ(2460)+→D∗+s π0)
σ(D+s )
= (3.5 ± 0.9 ± 0.2) × 10−2
Belle Preliminary
σ·B(DsJ(2460)+→D∗+s π0)
σ·B(D∗sJ(2317)+→D+
s π0)= 0.26 ± 0.05 ± 0.06
σ·B(DsJ(2460)+→D+s π0)
σ·B(D∗sJ(2317)+→D+
s π0)< 0.06 (90% C.L.)
17 Frank Porter, 17 July 2003, International Europhysics Conference on High Energy Physics
Summary
Two new narrow states have been observed with cs̄ content:D∗
sJ(2317) and DsJ(2460).They are consistent with being 0+ and 1+ states, respectively.
Their masses are lower than consensus expectation in cs̄ spectroscopy.
Mass of DsJ(2460) on margin of inconsistency among experiments:
BaBar 2457.0 ± 1.4 ± 3
Belle 2456.5 ± 1.3 ± 1.1
CLEO 2463.1 ± 1.7 ± 1.2Weighted Average∗ 2459.2 ± 1.2
∗ Adding systematic and statistical uncertainties in quadrature; neglect-ing possible correlations (eg, from D∗
s mass uncertainty of 0.7 MeV).χ2 probability for consistency is 3%.
For mass difference, weighted average is 346.6± 1.2, with 2% consistency.(Removes correlated D∗
s mass uncertainty).
More results expected soon!18 Frank Porter, 17 July 2003, International Europhysics Conference on High Energy Physics
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