New States in Charm Spectroscopy from Babar and Belle: a review

1
New States in Charm Spectroscopy from Babar and
Belle a review
byUsha Mallik (The University of
Iowa) International Conference on Relativistic
Hadronic and Nuclear Physics LC2007, Columbus,
OH, May 14-18

• An Intro
• DsJ Spectroscopy
• X,Y,Z states
• Charmed baryons
• News flash from
• Measurement of Spins
• D0-D0 Mixing
• Summary and Conclusion

2
What happens at ee- B-factory
e- beam energy 9.1 GeV, e beam energy 3 GeV,
E(cm) 10.58 GeV e- beam energy 8.0 GeV, e beam
energy 3.5 GeV, E(cm) 10.58 GeV
3
BELLE AND BABAR B AND c-FACTORIES

• Asymmetric ee- collisions at 10.58 GeV

Peak luminosity 17 x 1033 cm-2 s-1
710 fb-1 recorded
Belle
422 fb-1 recorded
Babar
4
Charm-strange mesons (cs) Ds, DsJ

• Ds0(2317) and Ds1(2460) surprising states
• DsJ(2860) another new state
• X(2690) and DsJ(2700) even more new states, or
  are they the same ?

5
Expected spectroscopy
6
Observed States
States prior to 2003 Even for 2573 2 not
established
DSJ(2317) and DSJ(2460) observed in ee- ? cc
Also observed in B-decays Well-established
experimentally - Masses and width - Natural
JP 0 for Ds0(2317) and 1 for Ds1(2460) -
Decay modes and Branching fractions
Interpretation of these new states still
unclear! One possibility identify these 2
states as the 0 and 1 cs states However strong
difficulties within the potential
model Semi-relativistic model Other
possibilities 4 quark states? DK molecule? D?
atom? Chiral symmetry?
Ground State DS(1969) JP0-, c and s spins
opposite, in S-wave
Belle Phys. Rev. Lett. 91 (2003) 262001 BaBar
Phys. Rev. D74 (2006) 032007 Belle
Belle-Conf-0461 (2006) BaBar Phys. Rev. D74
(2006) 031103
7
DsJ(2860) ANOTHER NEW STATE

• Looking in cc continuum
• ee- ? D0(K-?,K-??0)KX and ee- ?
  D(K-??)K0sX

D(K-? ?)K0s
D0(K-?)K
D0(K-? ?0)K
Ds2(2573)
Ds1(2536)
Ds1(2536)
240 fb-1
Ds2(2573)
Ds2(2573)
Ds1(2536)
New state at 2860 MeV/c2! Bump at 2690 MeV/c2?
BaBar Phys. Rev. Lett. 97 (2006) 222001
8
DsJ(2860) AND X(2690)?

• Combining the 3 modes
• M (2856.6 1.5 5.0) MeV/c2
• ? (47 7 10) MeV
• JP 0, 1-, 2,
• Final state is DK, i.e. two pseudoscalars
• Interpretation?
• Radial excitation of Ds0(2317)? hep-ph/0606110
• cs with JP 0?
  hep-ph/0608139
• cs with JP 3-?
  hep-ph/0607245
• Another structure at 2690 MeV/c2?
• M (2688 4 3) MeV/c2
• ? (112 7 36) MeV
• Need confirmation by other experiments

Sum of 3 modes
X(2690)
240 fb-1
Bkg subtracted
DsJ(2860)
BaBar Phys. Rev. Lett. 97 (2006) 222001
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EVEN MORE STATES DsJ(2700)

• Study of B ? D0D0K
• Looking at the Dalitz plot and the D0K
  projection
• New resonance decaying to D0K
• B ? D0DsJ, DsJ ? D0K
• M (2715 11 11-14) MeV/c2
• ? (115 20 36-32) MeV
• JP 1- favored
• Same resonance as seen by BaBar in continuum,
  X(2690)?
• Mass and width not inconsistent, same decay mode
• Interpretation?
• cs state 23S1?
• expected mass at 2720 MeV/c2
• Chiral symmetry 1 - 1- doubletpaired with
  Ds1(2536)?
• Phys.Polon. B 35, 2377 (2004)

D0K projection
Dalitz plot
DsJ(2700)
DsJ(2700)
Background
D0K projection
420 fb-1
DsJ(2700)
bkg subtracted
J1
414 fb-1
J0
J2
449 x 106 BB pairs produced
Belle hep-ex/0608031
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EVEN MORE STATES DsJ(2700)

• Study of B ? D()D()K decays in BaBar (22 modes)
• Looking at 8 DK 8 DK invariant masses, adding
  15 decay modes wrt Belle
• Enhancement observed around 2700 MeV/c2 in DK and
  DK
• Additional cs surprise? Maybe!
• One or two resonances around 2.6-2.7 GeV/c2 in
  DK?
• Need to perform a full Dalitz plot analysis
• Takes into account interferences

Summing all 8 DK modes
Summing all 8 DK modes
Ds1(2536)
New result preliminary
347 fb-1
Phase space
Background (generic MC)
BaBar preliminary
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CURRENT SITUATION
A Very Rich Spectroscopy in cs is emerging

• Ds0(2317), Apr. 2003 unexpected observation of
  a narrow resonance in BaBar

DsJ(2860)

• Ds1(2460), May 2003 CLEO, BaBar observed a new
  narrow resonance

X(2690)
DsJ(2700)

• DsJ(2860), Jul. 2006 new state discovered by
  BaBar

Ds1(2460)
Ds0(2317)

• X(2690), Jul. 2006 broad enhancement seen in
  BaBar

• DsJ(2700), Jul. 2006 new state discovered by
  Belle (? X(2690)?)

S wave P wave D wave
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NEXT The New Charmonia(-like) States ! The
Alphabet Soup !

• X(3872)
• X(3940), Y(3940) and Z(3930)
• Y(4260)

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The Charmonium(-like) States
hc
Below DD threshold states well understood. The
X,Y,Z states are all above the threshold
14
X(3872)
X(3872) ? J/???-

• First observation by BELLE in B decays
• B ?X(3872)K with X(3872) ? J/???-
• Confirmed by BaBar, CDF, D0
• M (3871.2 0.5) MeV/c2
• ? lt 2.3 MeV at 90 CL
• Observation of B ? X(3872)K,
• X(3872) ? J/? ?
• Implies CX(3872)1
• Belle, CDF ??- inv. mass distribution angular
  analyses
• L(??-) odd, I 1 ? J/??0?0 should not be
  observed
• JPC 1 favored
• BaBar search for a charged partner (decaying to
  J/??0?-)
• No signal ? I 0 ? I violated in J/???-

250 fb-1
X(3872) ? J/? ?
260 fb-1
Belle Phys. Rev. Lett. 91 (2003) 262001 Belle
hep-ex/0505038 BaBar Phys. Rev. D73 (2006)
011101 Belle hep-ex/0505037 BaBar Phys. Rev.
D74 (2006) 071101
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X(3872) STILL SOME SURPRISES

• Belle looking at B ? D0D0?0K
• Excess in the D0D0?0 invariant mass
• M 3875.4 0.7 1.2-2.0 MeV/c2

• BaBar looking at B ? D0D0K (D0 ? D0?0/?)
• Excess in the D0D0 invariant mass
• M 3875.6 0.7 1.4-1.5 MeV/c2

414 fb-1
347 fb-1
New result preliminary

• Masses between Belle and BaBar in good agreement
• 2.5? away from the X(3872) world average!
• If X(3872), JP 2 disfavored
  hep-ex/0606055

Belle Phys. Rev. Lett. 97 (2006) 162002 BaBar
preliminary
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X(3872) INTERPRETATION

• X(3872) likely not a charmonium state
• Radial excitation of ?c1 (JPC 1) expected at
  3950 MeV/c2
• If 3D1 or 3D2, radiative decays to ? states, not
  observed
• No satisfactory cc assignment
• D0D0 molecule? Prediction Phys.
  Rev. D71 (2005) 074005
• B0 ? X(3872)K0 suppressed by a factor 10 compared
  to B ? X(3872)K
• Measurements
• R(B0/B) 0.50 0.30 0.05 in B ? J/???-
  BaBar Phys. Rev. D73 (2006) 011101
• R(B0/B) 2.23 0.93 0.55 in B ? D0D0K
  BaBar Preliminary
• 4 quark state? Prediction
  Phys. Rev. D71 (2005) 014028
• Predict 2 neutral states and 2 charged states
• Neutral states produced in B0 and B decays ?m ?
  (7 2) MeV/c2
• Measurements
• ?m (2.7 1.3 0.2) MeV/c2 in B ? J/???-
  BaBar Phys. Rev. D73 (2006) 011101
• ?m (0.2 1.6) MeV/c2 in B ? D0D0K
  BaBar Preliminary
• Glueball? Hybrid?

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X(3940), Y(3940) AND Z(3930)
Y(3940)
X(3940)

• Near threshold enhancement in B ? J/?? K

• New state seen in ee- ? J/? X
• Also, observed X ? DD,
• but not X ? DD

253 fb-1
357 fb-1
M (3943 11 13) MeV/c2 ? (87 22 26)
MeV cc state ?c1 23P1?
Z(3930)
New resonance state in ?? ? DD

• M (3943 6 6) MeV/c2
• ? (15.4 10.1) MeV
• cc state ?c(3S) 31S0?

M (3929 5 2) MeV/c2 ? (29 10 2)
MeV cc state ?c2 23P2?
395 fb-1
Belle hep-ex/0507019 Belle Phys. Rev. Lett. 94
(2005) 182002 Belle Phys. Rev. Lett. 96 (2006)
082003
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Y(4260) ANOTHER MYSTERY

• New resonance discovered in ee- ? ?ISR(J/???-)
  by BaBar
• BaBar measures M (4259 8) MeV/c2, ? (88
  23) MeV
• Belle measures M (4295 10 10-3) MeV/c2, ?
  (133 26-2213-6) MeV
• Confirmed by CLEO M (4284 17-16 4) MeV/c2,
  ? (7339-25 5) MeV
• No evidence for
• ee- ? ?ISR(DD), ee- ? ?ISR(???-), ee- ?
  ?ISR(pp), ee- ? ?ISR(J/???)
• 3? enhancement in B decays
• B-?YK-, Y?J/???-
• Needs confirmation

JPC1--
233 fb-1
553 fb-1
BaBar Phys. Rev. Lett. 95 (2005) 142001 Belle
hep-ex/0612006 BaBar hep-ex/0607083 BaBar PRD
73, 011101 (2006) Cleo-c PRD 74, 091104 (2006)
19
Y(4260)... AND Y(4325)?

• Study of Y(4260) ? ?(2S)?? in ISR production
• Incompatible
• with BaBar Y(4260), ?(4415) or 3-body phase space
• Compatible
• with Belle Y(4295)

Preliminary
M (4324 24) MeV/c2 ? (172 33) MeV
298 fb-1
BaBar hep-ex/0610057
20
Y(4260) INTERPRETATION

• No cc assignment for 1-- state
• Probably not a glueball
  Phys. Lett. B625 (2005) 212
• No evidence for Y(4260) ? ???
• 4 quark state cscs?
  Phys. Rev. D72 (2005) 031502
• Should decay dominantly to DsDs
• Hybrid meson?
• DD, DD, DD decays suppressed
• DD1(2420) decays should dominate
• ??c1 molecule?
  Phys. Lett. B634 (2006) 399
• hybrid quenched lattice QCD predicts, for 1--
  
• M 4380 150 MeV/c2
  Phys. Rev. D74 (2006) 034502

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CC Summary

• Possibly charmonium states
• X(3940) ?c(3S)? Y(3940) ?c1? Z(3930)
  ?c2?
• Probably NOT charmonium states (what are they?)
• X(3872), Y(4260), Y(4325)

Y(4260)
Y(3940) ?c1?
X(3940) ?c(3S)?
Z(3930) ?c2?
X(3872)
22
NEXT The Status of Charmed Baryons
23
Baryons with 4 flavors (u,d,s,c)
4?4?4 4 ?20?20?20
1/2
3/2
Ground states

u,d,s, octet
Anti-symmetric
Ground state
1/2-
u,d,s, decuplet
All 9 ground states c1, JP ½ observed
5 ground states with JP 3/2 observed only ?c
was missing
24
About charmed baryons
Anti-symm under the interchange of the two light
quarks (u,d,s)
symm. under the interchange of the two light
quarks (u,d,s)
Charmed baryons can be produced from continuum or
from B-decays
Characteristics momentum of charmed baryon in
ee- rest frame, p high when produced in cc,
low when produced in B decays
25
Charmed Baryon States
Most of the JPs assigned none measured
26
Observation of ?c(2880) and ?c(2940) decaying
to D0p
BaBar PRL 98012001(2007)
?c(2940)
New Decay mode ?c(2880) ? D0p First observation
of charm baryon ? charm meson
?c(2880)
Nsig2280?310
Belle confirms in ?c ? (?c??)
Belle Hep-ex/0608043
?c(2765)
Wrong sign D0P
?c(2880)
?c(2940)
D0p invariant mass GeV/c2
D0 mass sidebands
M(?C ? ?-) GeV/c2
Excellent agreement in mass and width
27
Observation of ?c(2815) ?c(2980)
414 fb-1
preliminary
hep-ex/0608012
28
preliminary
29
?c0 Production and Decay
?c0 Decay
PDG values
hep-ex/0703030, submitted to PRL
30
?c0 Production in B decays
hep-ex/0703030, submitted to PRL
From B decaysfirst observation
Continuum production
p distribution, momentum in the ee- rest frame
Off-peak data Below B-pair thres-hold, no peak
31
BaBar PRL 231 fb-1 97232001(2006)
Discovery of the ?C

Data from all four ?c0 decay modes are combined
and fit yields 105 ? 21 ? 6 5.2?
signal significance
No signal found in the ?c0 mass Sidebands
(hatched area)
?m ( m?c - m?c0) (70.8 ? 1.0 ? 1.1) MeV/c2
Theory range ?m 50 94 MeV/c2
1.01? 0.23? 0.11
Combined
For XP gt 0.5, most/all the ?c0 might result from
?c production, but uncertainty is large.
32
Also observed the charged partner ?c
33
Measurement of Absolute Branching Fraction of ?c
34
Measurement of B ? ?cp?
35
Study of b ? ccs decay
BABAR, PRL. 95 142003, 2005 PRD
75 012003, 2007
Inconsistency in the MC and data p distribution
MC only has b ? cud
Search B decays into charm-baryon-anti-charm-baryo
n pair
B ? ?c?c and B ? ?c ?c K
36
B decays to ?c?c and ?c ?cK
An example
?E energy difference between reconstructed B
and Ecm mES beam momentum substituted
reconstructed B mass ee- BB
37
B decays to ?c?c
PRD 74 (2006) 111105
38
B decays to ?c ?cK
PRL 97 (2006) 202003
39
NEXT Spin Measurements
40

• Examine implications of W- spin hypotheses
• for angular distribution of L from W- decay

?(L) 1/2
q
quantization axis
?(K) 0
J 1/2 m 1/2 m - 1/2
?(K) 0
?
l(W) 1/2 l(W) - 1/2
W- inherits the spin projections of the Xc0
since, no orbital angular momentum projection
w.r.t. quantization axis in ?c0 decay

• Initial helicity, ?i ? (W) 1/2
• Final state helicity, ?f ? (L) -
  ?(pseudoscalar) 1/2
• Decay amplitude for O- ? ? K-

41
Spin measurement of W- from Xc0 ? W- K, W- ?
L K- decays
Data 116 fb-1
Background-Subtracted Efficiency-Corrected
PRL 97 (2006) 112001
Similar conclusion from Wc0 ? W-p, W- ? LK-
decays
ConclusionJ(W-) 3/2
assumingJ(Xc0) 1/2
JW 1/2
? Fit Prob 10 -17
JW 3/2
? Fit Prob 0.64
? Fit Prob 10 -7
JW 5/2
42
Extending the Spin Formalism to 3-body Decays
Study of X (1530)0 and X (1690)0

• The X (1530)0 Spin from Lc ? (X- p) K
  ? also mass, width info. ?
  amplitude analysis (in progress)? The X (1690)0
  Spin from Lc ? (L0KS0) K
  ? also mass, width info. ? amplitude analysis
  (to be done) ? (X-p)/(LK0) Branching Ratio
  Limit (to be done)

12
43
NEXT D0 D0 Mixing
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Time-Evolution of D0 Decays
D0 can reach the K ?- final state in two
ways 1) Doubly-Cabibbo-Suppressed decay 2)
Mixing to D0bar, followed by Cabibbo-Favoured
decay ... and interference between them.
Q How can we distinguish these? A By the time
evolution.
46
Summary
PDG 2006

• Mixing contours from 2006 PDG
• Kp decay the dominant mode in the search for
  mixing
• CP lifetimes sensitive to measuring y
• Semileptonic sensitive to RM (x2y2)/2

95 CL allowed
CPV allowed
yCP(0.90?0.42)
?K?0? assumed
dKp 0? measured by CLEO
47
Summary
hep-ex/0703036 Submitted To PRL(Belle) hep-ex/0703
020 Submitted To PRL (BaBar) 0704.1000v1
hep-ex, Moriond EW/QCD 2007(Belle)
Updated with new results for this talk (HFAG
plots will be available soon)

• Assuming CP conservation BaBar has found evidence
  for mixing at 3.9s CL using D0?Kp decay mode (384
  fb-1)
• ycp by Belle also evidence for mixing at 3.2s CL
  (540 fb-1)
• Clear Evidence of Mixing
• Most sensitive measurement of x by Belle
  (D0?Kspp)
• A precision measurement of cosd needed to express
  mixing in x and y
• CLEO-c quantum correlation
• BaBar and Belle B-factories
• Are also charm factories
• Searches for CP violation
• Improved techniques
• More data

95 CL allowed
CPV allowed
Belle ycp (1s)
Belle ycp
BaBar Kp
Belle Kspp
?K?0? assumed
dKp 0? measured by CLEO
48
Some Recent Theoretical Work

• D-Dbar Mixing And New Physics General
  Considerations and Constraints on the MSSN (M.
  Ciuchini et al)
• hep-ph/0703204v1
• Lessons from BaBar and Belle measurements of
  D0-D0bar mixing parameters, (Y. Nir)
• hep-ph/0703235v1
• Littlest Higgs Model with T-Parity Confronting
  the New Data on D0-D0bar Mixing,(M. Blanke et al)
• hep-ph/0703254v1
• Basics of D0-D0bar Mixing, (P. Ball)
• hep-ph/0703245v1

49
Summary

• Experimental status
• A new landscape in many areas including
  spectroscopy has opened up with high luminosity
  and precision
• New DsJ Spectroscopy
• X, Y, Z States
• Charmed Baryon Spectroscopy
• Spin Measurements (necessary to identify levels,
  complex analysis for multi-body states ?c
  (1530), ?c (1690), in Charmed Baryon decays )
• Evidence for D0-D0 Mixing
• Lots of on-going analyses with the current
  dataset
• More decay modes investigated to understand these
  resonances
• Lots of new data to analyse!

Expecting three/four times more data than shown
in analyses A race to find Beyond Standard Model
Physics
50
Example Mixing
One of the main HEP discoveries in 2006 Bs
Oscillations
x24.8 y0.1?
Bs0 oscillate very rapidly
Rate first measured in 2006 by CDF and D0
Toy MC
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Fit Results
Evidence for D0-D0 mixing!
53
Many validation tests done
Most powerful is performing a time-independent
fit of the Wrong-Sign and Right-Sign yields in
slices of proper lifetime
Consistent with prediction from full likelihood
fit ?21.5
(stat. only)
Inconsistent with no-mixing hypothesis ?224
Ratio of WS/RS events clearly increase with time.
Mixing signal!
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B-Factories production processes
Production in continuum s1/2 10.58 GeV - Two
photons production - Double charmonium
production - Initial State radiation
Production in B decay s1/2 5.28 GeV b?c color
suppressed transition charmonium and open-charm
27
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Legendre Polynomial Moments in Spin Determination

For W- spin J, the previous angular distributions
can be written
9
59
Illustration of the Use of Legendre Polynomial
Moments in Spin Determination

(will prove
useful later)
wj v10 P2(cosq) from Xc0 signal region

• - ?
• signal

W- ? signal
? efficiency-corrected , mass-sideband-subtract
ed unweighted m(L K-) distribution in data
efficiency-corrected v10 P2 (cosq) weighted
efficiency-corrected (7/ v2) P4 (cosq) weighted
60
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62
Observation of b ? ccs
? cw- (W- ? cs)
Charm baryon pair production in B Decays
W-
W-
63
List of Decay Modes (pair production)
Reconstruct the B meson Use energy momentum
conservation between ee- cm and BB in cm
Look for signal events in the mes, ?E 2D
distribution
64
Fit to Signal
B- ? ?c ?c K-
Analysis ongoing
pK-?
65
Study of ?c0 (css)

• Production Process and Ratio of Branching
  Fractions of ?C0 (css)
• cc or B ? ?C0 X
  ?C0 ? ?- ?
• 
  ? ?- ? ?- ?
• 
  
  ??-K- ? ?

Preliminary results shown at 2005 summer
conferences Improved analysis using likelihood
selection in progress
66
Helicity Formalism, Spin Determination

• Suited to two-body (successive) decays
• Can be extended to intermediate resonances
• (ie, quasi-twobody decays using Dalitz plots)

67
Helicity angle of ? Angle made by p(?) in ?-
rest frame with p(?-) in ?c0 rest frame
?
?c0
?-
K
K-
Xc0 ? K W- ? L0 K-
?K 0
J 1/2 m 1/2 m - 1/2
?f 1/2
?K 0
?i 1/2 ?i - 1/2

• J(?c0) 1/2 ? in ?c0 rest-frame m 1/2
  along z (quantization) axis
• no angular momentum projection w.r.t.
  quantization axis ? O- helicity, ?i 1/2
• final state helicity ?f ?f (?0) - ?f
  (pseudoscalar) 1/2
• Decay amplitude for O- ? ?0 K-
• ?Total Intensity

Does not depend on li Wigner-Eckart theorem
68
Spin measurement of W-
Background-Subtracted Efficiency-Corrected
? Fit Prob 10 -17
JW 1/2
JW 3/2
? Fit Prob 0.64
? Fit Prob 10 -7
JW 5/2
69
Spin measurement of W- from Xc0 ? W- K, W- ?
L0 K- decays
Angular Distribution Parametrizations for JO3/2
hypothesis
Background-Subtracted Efficiency-Corrected
Negligible Decay Asymmetry Parameter
b 0.04 0.06
No Asymmetry
b 0
Asymmetry
Fit for b ? b 0.04 0.06
9
70
Spin measurement of Wc0 from Wc0 ? W- p, W- ?
L0 K- decays
Fit parametrization a(1 3 cos2?) for JO 3/2
hypothesis ? Fit Prob 0.69 J(W-) 3/2,
consistent with
results from Xc0 ? W- p
PRL version ready for review comm
Conclusion J(W-) 3/2 Assuming J(Xc0) ,
J(Wc0) lt5/2
71
Reconstructed Lc ? X- p K, X- ? L0 p-
Events
m(X- p) ? Lc mass-signal region ? m(X-
p) ? Lc mass-sideband region .



. m(X- p) ? (Lc)
mass-sideband-subtracted
Data 230 fb-1
Uncorrected
(Lc)Mass-sideband-subtracted
Uncorrected
? Lc ? X- p K
? X(1530)0 ? X- p
PDG mass
13
72
Resonant Structures in Lc ? X- p K, X- ? L0
p- Events
Only obvious structure X (1530)0 ? X- p
Lc signal region
73
Spin measurement of X0(1530) from Lc ?
X0(1530) K, X0(1530) ? X- p decays
a(1 3 cos2?) for J3/2 hypothesis
Uncorrected cos?X Spectrum
Clear 13cos2? structure
X0(1530) Signal Region Not mass-sideband-subtrat
ed
X0(1530) Mass-Sideband Regions

• Skewed distribution due to
• Efficiency loss at small angles ? Not big
  effect
• (X- p) system decay asymmetry ? S-P wave
  interference (next slides)

74
Using the angular structure of X(1530)0 ? X- p
candidates to project
away
background events
Lc ? X- p K Signal Region Uncorrected
sidebands
? Legendre polynomials orthogonality condition
? Weight N x P2(cosq)
For pure spin 3/2 dN/dcosq a(1 3 cos2q)
Use of angular structure to project away the
bkgr.
Lc Signal Region
Projects mass distribution having cos2q component
Lc Low Mass-Sideband Region
100

• No cos2q component
• in sideband distributions

Lc High Mass-Sideband Region
100
75
Evidence of S-P wave interference in the (X- p)
system produced in the

decay Lc ? X- p K
m(X- p) distribution weighted by P1(cosq)
76
S-P wave description of the (X-p) system
produced in the decay Lc ? X- p K
K
Amplitudes describing the (X- p) system
? Total Intensity
77
Helicity Formalism (3)
Assume 0 to extract cosq
S-P interference
0 (Assume r1/2 r-1/2)
78
towards a measurement of the mass width of
X0(1530)
L 2, 1
p
X0(1530) J3/2
q
K
X0(1530)
l 1 () parity
p
X-
Fit with relativistic Breit-Wigner Function with
L2 l 1 incorporating a Blatt-Weisskopf
barrier factor (R 5 (GeV)-1) and resolution
smearing
p
q
p
q
Fit Params M 1531.6 0.1 (stat.) G 11.9
0.2 MeV
PDG M 1531.80 0.32 G 9.1 0.5 MeV
Uncorrected
P2(cosq) weighted
(Very preliminary)
In progress
79
Reconstructed Lc ? L0 KS0 K Events
(Lc)Mass-sideband-subtracted
? X(1690)0 ? L0 KS0
80
towards a measurement of the mass width of X
(1690)0 ? L0 KS0
Only obvious structure X (1690)0 ? L0 KS0
S-Wave Breit-Wigner Function ( Linear
bkgr.) with resolution smearing
Uncorrected
Fit Params M 1684.7 - 0.9 (stat.) G 12.0 -
0.2 MeV
Background-subtracted Uncorrected
(Very preliminary)
Stop fit at 1.76
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81
Spin measurement of X(1690)0 from Lc ? X(1690)0
K, X0(1690) ? L0KS0 decays
Uncorrected Background-Subtracted
cos?L Spectrum
Direct Method - Extract signal cosqL
distribution - Requires large sideband
subtraction
Flat ? consistent with J1/2 hypothesis
a(1 3 cos2?) for J3/2 hypothesis
prob 0.2
a(1) for J1/2 hypothesis
prob 0.9
Inconclusive
Spin 1/2 favored ?
Indirect Method
Lc signal region
Uncorrected
Uncorrected
m(L KS) distribution weighted by P2(cosq) ?
Lc signal events
? No cos2q component anywhere ? Spin 1/2
? Spin hypothesis Weight signal events by
P2(cosq)
24
82
towards an U.L. on BR(X (1690)0 ? X- p )/BR(X
(1690)0 ? L0 KS0 )
Uncorrected (L0 KS0) invariant mass Lc ? L0
KS0 K Clear signal for X (1690)0 ? L0 KS0
Lc ? L0 KS0 K
Background-subtracted
Lc ? X- p K
Background-subtracted
Uncorrected (X- p) invariant mass Lc ? X- p
K No signal for X (1690)0 ? X- p
83
X0 Production in Lc Xc0, Decays
cancel
84
Investigation of Xc,0 Decaysto 3-body Final
States

• Xc ? X- p p ? Xc ? L0 KS0 p ? Xc0 ? L0
  K- p

85
Reconstructing Xc ? L0 KS0 p Events
Data 200 fb-1
? DS 0
? DS -1
Cabbibo-suppressed Lc ? L0 K0 p
86
Lc ? L0 K0 p Dalitz Plot Analysis
Obvious resonant structures
Mass-sideband-subtracted
K(892)? KS0p?
Large K(892) contrib.
Uncorrected
S(1385)
Mass-sideband-subtracted
Uncorrected
K(892) Yield/ 10 MeV/c2
? S(1385) ? L0 p
Evidence for the decay Lc ? L0 K(892)
? Previously observed C.S. mode Lc ? S
K(892)0
87
Excited Charm Baryons
88
Excited Xc States
L0 straightforward
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90
X(3872) BELLE Finds Data Disfavors 0 and 2,
Leaving 1
cc ? 1 is ?c1
Solid lines Experiment Left NR model, Barnes,
Godfrey, Swanson Right Relativized model,
Godfrey, Isgur (Spin) Singlets dotted, Triplets
dashed
X(3872) is too light
91
BABAR
230 fb -1
e
e-
Detector Tomography with pKS0 vertices
92
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