Dalitz Plot Analysis of D0?K0K K- and DsJ states

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Dalitz Plot Analysis of D0?K0KK- and DsJ states

• Marco Pappagallo
• University of Bari INFN
• (on behalf of the collaboration)

12th Lomonosov Conference on Elementary Particle
Physics Moscow, August 25 31,2005
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Outline

• BaBar Detector
• Dalitz Plot Analysis of D0?K0KK-
  (hep-ex/0507026)
• BR of D0?K0KK- / D0?K0??-
• Partial Wave Analysis
• Dalitz Plot Analysis
• CP asymmetries
• DsJ states
• DsJ(2317)/DsJ(2460) (hep-ex/0408067)
• Search for radiative and dipion transitions
• Four-quark content
• DsJ(2632) (hep-ex/0408087)

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PEP II B-Factory

• Data
• 90 _at_ vs 10.58 GeV ?(4S)
• 10 _at_ vs 10.54 GeV qq

• 288 fb-1 so far recorded

ee-? s(nb)
bb 1.05
cc 1.30
ss 0.35
uu 1.39
dd 0.35
tt- 0.94
µµ- 1.16
ee- 40
374M cc pairs
PEP II is also a charm factory
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BaBar Detector
Electromagnetic Calorimeter(EMC) 6580
crystals(CsI) e- Id ?0/? reconstruction
Instumented Flux Return(IFR) 19 layers of
RPC/LST ? KL Id
e(3.1 GeV)
1.5 T solenoid magnet
Drift Chamber(DCH) 40 layers Tracking dE/dx
e-(9.0 GeV)
Silicon Vertex Tracker(SVT) 5 layers of double
sided silicon strips Tracking(with DCH),
tracking(SVT only), dE/dx
Cherenkov Detector(DIRC) 144 bars (fused
silica) K/? -separation
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Scalar Mesons JPC0

• On the experimental side
• Scalar mesons are difficult to resolve because
  of their large decay widths, and the presence of
  non-BW-like amplitude contributions at low mass
  value (e.g. LASS K? S-wave parametrization).
• On the QCD theory side
• Scalar meson candidates are too numerous to fit
  in a single qq nonet. Some of them may be
  multiquark, KK or other meson-meson bound states.
• Many models expect a glueball with mass in the
  range 1.5 - 1.8 GeV

I 1 I ½ I0
f0(600)?
a0(980) k(800)? f0(980)
f0(1370)
a0(1450) K0(1430) f0(1500)
f0(1710)
(F.E. Close and N.A. Tornqvist J.Phys.G28,R249)
Study of D and Ds mesons decays shed light on the
light-quark Scalar Meson Sector
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D0?K0hh- decay hK/?
D0s are required to result from a D meson decay
CF
DCS
Charge of slow pion ?s determines the D0 and K0
flavour. Presence of Doubly Cabibbo Suppressed
contribution may lead to misidentification of K0
flavour.
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D0?K0hh- decay hK/?
4s0
4s1
Event selection uses
K0KK- mass resolution better than K0??- one due
to a smaller Q-value involved
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B.R. (D0?K0KK- / D0?K0??-)
Number of events in a given Dalitz plot cell (x,y)
Efficiency correction ei Samples of Monte Carlo
events generated according to phase space and
subjected to the same reconstruction and event
selection procedure as for the data
B.R.(15.8 ? 0.1(stat.) ? 0.5(syst.))x10-2 PDGB.R
.(17.2 ? 1.4)x10-2
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Partial Wave Analysis
Large Forward-Backward Asymmetry variation with
the KK- mass due to interference between
S-wave(a0(980)/f0(980)) and P-wave(F(1020))
Contribution due to a0(980) doesnt overlap with
the F(1020) region. A partial wave analysis in
the low mass KK- region allows the KK- scalar
and vector components to be separated resolving
S.U. Chung, Phys. Rev. D56, 7299(1997)
Weight each event by Y0l(cos ?K)/? (l0,1,2)
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Partial Wave Analysis

• MODEL
• KK- system F(1020) and a0(980)
• No evidence of f0(980) comparing K0K and KK-
  (normalized) S-waves
• K0K system a0(980)

Simultaneous fit to P2, S2, m(K0 K), fSP
FREE
gkk 473 29(stat.)?40(syst.) (MeV)1/2 Crystal
Barrel gkk 328 ? 27 (MeV)1/2 A.Abele et al.,
phys. Rev. D57, 3860(1998)
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Dalitz Plot Analysis of D0?K0KK-
Results of a unbinned maximum likelihood fit
Final State Amplitude Phase(radians) Fraction()
K0a0(980)0 1. 0. 66.41.67.0
K0F(1020) 0.4370.0060.060 1.910.020.10 45.90.70.7
K-a0(980) 0.4600.0170.056 3.590.050.20 13.41.13.7
K0f0(1400) 0.4350.0330.162 -2.630.100.71 3.80.72.3
K0f0(980) 0.40.20.8
DCS Ka0(980)- 0.80.30.8
Sum 130.72.2
Outcome

• Decay is dominated by D0?K0a0(980)0,
  D0?K0?(1020) and D0?K- a0(980)
• DCS and f0(980) contributions consistent with
  zero
• Presence of tail of a broad resonance (f0(1400)?)

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Search for CP asymmetries
The Dalitz plot analysis has been separated for
D0 and D0
No statistically significant asymmetries in
fractions, amplitudes or phases
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DsJ states
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Heavy Meson Spectroscopy Theory
l
Potential Model
cs system considered as a hydrogen atom
? Ds2(2573)
? Ds1(2536)
States predicted to have large widths


S. Godfrey and N. Isgur, Phys. Rev. D32,
189(1985) M. Di Pierro and E. Eitchen, Phys.
Rev. D64, 114004(2001)
l 0
l 1
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Two new states DsJ(2317)?Ds?0
DsJ(2317)

• Unbinned Maximum Likelihood Fit
• Presence of 2 reflections
• No evidence of DsJ(2460)

DsJ(2460)?Ds(Ds?)?0
Ds?
DsJ(2460)
m(DsJ(2317))2318.9?0.3(stat.)?0.9(syst.)
MeV/c2 (below D()K threshold)
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Two new states DsJ(2460)?Ds?0
High Ds sideband
DsJ(2460)
DsJ(2317)?
Ds??

• Unbinned Maximum Likelihood Fit
• Presence of 2 reflections
• No evidence of DsJ(2460)?DsJ(2317)?

Low Ds sideband
m(DsJ(2460))2459.1?1.3(stat.)?1.2(syst.)
MeV/c2 (below DK threshold)
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DsJ(2317),DsJ(2460) ? (0,1) missing states?
Search for radiative and dipion transitions in
order to confirm or rule out some of these
hypotheses
Ds??- (JP0-,1?,2?)
Ds? (JP1?,2?,)
Ds1(2536)
DsJ(2460)
DsJ(2317)
Absence consistent with JP0 allowed for all
other natural parity
B?D DsJ(2460)?Ds? angular distribution favours
J1
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Four-Quark Content in DsJ states?
Some authors have discussed the possibility of a
four quark content in DsJ states in order to
explain the low mass of these states
T. Barnes, F.E.Close and H.J.Lipkin, Phys.
Rev., D68, 054006(2003) H. J. Lipkin, Phys.
Lett. B580, 50(2004) T.E. Browder, S. Pakvasa,
and A. A. Petrov, Phys. Lett. B578, 365(2004)
DsJ(2317)0
No evidence for isovector partners of DsJ(2317)
DsJ(2317)0 , DsJ(2317)
I0 Decay to Ds?0I1 possible via ?/?0 mixing
DsJ(2317)
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Search for DsJ(2632)?Ds?
SELEX
?lt17MeV yet well above threshold ?(D0K)/?(Ds?)0.
14?0.06 but D0K has a 1.5x phase space
N(Ds)196000
N(?)3900
BABAR
?s associated with Ds production!
125 fb-1

• Ds??(1020)?, K(892)0K
• ???? where
• ? ??0???
• ? ?Ds?Ds?

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Nine Tiles Method
1
3
2
4
5
6
7
9
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Evidence of correlated Ds and ? production
Opposite jet
No evidence of DsJ(2632)
Same jet
Background Subtraction
m(Ds?) distribution of tile No.5
(zoom)
Background contribution coming from tiles
No.1-46-9
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Search for DsJ(2632)?D0Kand DKs0 too
Ds2(2573)
Ds1(2536)
Not shown by SELEX
D0K-
BaBar sees no evidence for DsJ(2632)?D0K and for
DsJ(2632)?DKs0 in 125 fb-1 data
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Conclusion

• Dalitz Plot Analysis of D0?K0KK-
• a0(980)/f0(980)?KK lineshape extracted with
  little background. Further information may result
  from a Dalitz Plot Analysis of D0?KS0??0
• No evidence of CP asymmetries
• DsJ states
• DsJ(2317) observed in Ds?0 system
• DsJ(2458) observed in Ds?0, Ds?, Ds??-
• No evidence for isovector DsJ(2317) partners
  predicted by four quark model
• Evidence so far points out that DsJ states may
  be interpreted as cs states yet, the low mass of
  the DsJ states has still to be understood.
  Evidence of new decay modes (Ds?0?0,Ds?) may
  confirm the correctness of such a hypothesis.
• No evidence for a DsJ(2632) state reported by
  SELEX

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Backup Slides
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Partial Wave Analysis
S.U. Chung, Phys. Rev. D56, 7299(1997)
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Partial Wave Analysis
Dalitz Plot Projection
?(1020) reflection
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Search for CP asymmetries
Decay Mode Fraction() Amplitude Phase(radians) ?2/NDF
D0? K0a0(980)0 66.52.0 1. 0. 671/649
D0?K0a0(980)0 66.32.0 1. 0. 643/646
D0? K0?(1020) 46.30.8 0.4380.009 1.930.03
D0? K0?(1020) 45.60.8 0.4350.009 1.880.03
D0? K-a0(980) 13.21.3 0.4560.025 3.580.07
D0? Ka0(980)- 13.61.3 0.4630.025 3.590.07
D0? K0f0(1400) 4.10.9 0.4510.047 -2.580.13
D0? K0f0(1400) 3.60.9 0.4210.038 -2.680.14
The Dalitz plot analysis of D0 and D0 dont show
any statistically significant asymmetries in
fractions, amplitudes or phases
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Two new narrow states
DsJ(2317)_at_BABAR
BABAR
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DsJ(2317)?DsJ(2460)
Mutual cross feed
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Likelihood Fit of Ds?0? System
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3
2
4
5
6
7
9
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Result of a likelihood fit to the Ds?0 and Ds?
masses of the Ds?0? candidates. The points
correspond to the data. The histograms are a
Monte Carlo representation of the fit results.
Shown in gray(black) are the contributions from
DsJ(2460)?Ds(2112)?0 (DsJ2460)?Dsj(2317)?)
decay predicted by the fit. The light gray area
is the contribution from combinatorial
background.
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Likelihood Fit of Ds? System
No evidence of DsJ(2317)?Ds?
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DsJ(2317),DsJ(2460)
Preliminary results
_at_95 c.l.