1 New States in Charm Spectroscopy from Babar and Belle: a review • An Intro • D sJ Spectroscopy • X,Y,Z states • Charmed baryons • News flash from – Measurement of Spins – D0-D0 Mixing • Summary and Conclusion by Usha Mallik (The University of Iowa) International Conference on Relativistic Hadronic and Nuclear Physics – LC2007, Columbus, OH, May 14-18
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1 New States in Charm Spectroscopy from Babar and Belle: a review An Intro D sJ Spectroscopy X,Y,Z states Charmed baryons News flash from –Measurement.
3 BELLE AND BABAR: B AND c-FACTORIES 710 fb -1 recorded Belle Asymmetric e + e - collisions at GeV Babar 422 fb -1 recorded Peak luminosity 17 x cm -2 s -1
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1
New States in Charm Spectroscopy from Babar and Belle: a review
• An Intro
• DsJ Spectroscopy
• X,Y,Z states
• Charmed baryons
• News flash from– Measurement of Spins
– D0-D0 Mixing
• Summary and Conclusion
byUsha Mallik (The University of Iowa)
International Conference on Relativistic Hadronic and Nuclear Physics – LC2007, Columbus, OH, May 14-18
2
What happens at e+e- B-factory
e- beam energy 9.1 GeV, e+ beam energy 3 GeV, E(cm) = 10.58 GeVe- beam energy 8.0 GeV, e+ beam energy 3.5 GeV, E(cm) = 10.58 GeV
b
b
b
q
q
b
(4S)
B
B
(10580) MeV
e+e- 4S) BB also cc, ss, uu, dd
(5279MeV)
e+e- bb) 1.05 nb (cc) 1.30 nb (uds) 2.09 nb
timeAlso a charm factory
3
BELLE AND BABAR: B AND c-FACTORIES
710 fb-1
recordedBelle
Asymmetric e+e- collisions at 10.58 GeV
Babar 422 fb-1
recorded
Peak luminosity 17 x 1033 cm-2 s-1
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
DSJ(2317)+ and DSJ(2460)+ observed in e+e- cc
States prior to 2003
Even for 2573: 2+ not established
Also observed in B-decaysWell-established experimentally - Masses and width
- Natural JP: 0+ for Ds0*(2317) and 1+ for Ds1(2460)
- Decay modes and Branching fractions
Ground State DS(1969)+: JP=0-, c and s spins opposite, in S-wave
Observed States
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 modelSemi-relativistic model
Other possibilities:4 quark states? DK molecule? D atom? Chiral symmetry?
– Probably NOT charmonium states (what are they?)• X(3872), Y(4260), Y(“4325”)
CC Summary
Y(3940) = ’c1?X(3940) = c(3S)?
Z(3930) = ’c2?
X(3872)
Y(4260)
22
NEXT
The Status of Charmed Baryons
23
Baryons with 4 flavors (u,d,s,c)
3/2+1/2+
1/2-u,d,s, decuplet
u,d,s, octet
Ground states
Ground state
= 4 20’20’20
Anti-symmetric
*
5 ground states with JP = 3/2 observed: only c* was missing
All 9 ground states c=1, JP = ½ + observed
24
The singly charmed u,d,c sub-multiplets from the 20’ 9 members; JP = 1/2
(2698)
(2285)
(2472)(2466)
(2574)(2579)
3 6
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)
Charm baryon + X
e+e- BB
e+e- cc
Charmed baryons can be produced from continuum or from B-decays
Characteristics: momentum of charmed baryon in e+e- rest frame, p*: high when produced in cc, low when produced in B decays
25
c(2800)
Charmed Baryon States
Belle
Babar
Cleo
Most of the JP’s assigned none measured
26
Observation of Λc(2880)+ and Λc(2940)+ decaying to D0p
New Decay mode: Λc(2880)+ D0p First observation of charm baryon charm meson
Nsig=2280310Λc(2940)
Λc(2880)
Wrong sign D0P
D0 mass sidebands
Λc(2765)Λc(2880)
Λc(2940)
Belle confirms in c (c)
BaBar PRL 98:012001(2007)
M(ΛC + -) GeV/c25410 1.8
0.4-1.02937.9 1007060-40-210 )2940(c
4.00.70.3-5.5 0.4
0.3-0.22881.2 4050880 )2880(c
5.95.217.5 1.01.32939.8 3102280 )2940(c
1.11.55.8 0.50l.2881.9 190 2800 )2880(c
[MeV] ]2M[MeV/c Yield sonanceRe
D0p invariant mass GeV/c2
Belle Hep-ex/0608043
Excellent agreement in mass and width
27
414 fb-1
preliminary
hep-ex/0608012
Observation of c(2815) & c(2980)
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cx(3077)+
cx(2970)+
New charm strange baryons BaBar confirms these states
Belle, PRL97:162001(2006) BaBar hep-ex/0607042
preliminary
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c0 Production and Decay
PDG values
c0 Decay
hep-ex/0703030, submitted to PRL
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From B decays:first observation
Continuum production
Off-peak data: Below B-pair thres-hold, no peak
c0 Production in B decays
p* distribution, momentum in the e+e- rest frame
hep-ex/0703030, submitted to PRL
-410 Few )0( XcBB
31
Discovery of the C*
Combined
BaBar PRL 231 fb-1
97:232001(2006)
)2GeV/c(pdgMMM 0c
0c
*c
Data from all four c0
decay modes are combined and fit yields: 105 21 6 5.2 signal significance
m ( mc* - mc0)= (70.8 1.0 1.1) MeV/c2
Theory range: m = 50 – 94 MeV/c2
= 1.01 0.23 0.11
For XP > 0.5, most/all the c0 might result from
c* production, but uncertainty is large.
No signal found in the c0 mass
Sidebands (hatched area)
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
Inconsistency in the MC and data p* distribution: MC only has b → cud
Search B decays into charm-baryon-anti-charm-baryon pair
B → cc and B → c c K
BABAR, PRL. 95 142003, 2005 PRD 75 012003, 2007
36
B decays to cc and c cK
E = energy difference between reconstructed B and Ecm
mES : beam momentum substituted reconstructed B mass: e+e- BB
An example
37
B decays to cc
PRD 74 (2006) 111105
38
B decays to c cK PRL 97 (2006) 202003
39
NEXT
Spin Measurements
40
- inherits the spin projections of the c0
Examine implications of - spin hypotheses for angular distribution of from - decay
Initial helicity, λi = λ ()= ± 1/2 Final state helicity, λf = λ () - λ(pseudoscalar) = ± 1/2
Decay amplitude for Ω- → Λ K-: ffifiADA JJ
)0,,(*
λ() = ± 1/2
λ(K) = 0
λ(K) = 0J = 1/2m = + 1/2m = - 1/2
) = + 1/2() = - 1/2
quantization axis
K-
-K+(+) c
0 = 0 c
- = 0
since, no orbital angular momentum projection w.r.t. quantization axis in Ξc0 decay
41
)cos5cos21(
)cos31(
1
42
2
I
I
I
Spin measurement of - from c0 → - K+, -
→ K- decays
→ Fit Prob = 10 -17
→ Fit Prob = 0.64→ Fit Prob = 10 -7
Background-SubtractedEfficiency-Corrected
J = 1/2
J = 5/2
J = 3/2
Data
~ 116 fb-1
Similar conclusion from c
0 → -+, - → K- decays
[assumingJ(c0) = 1/2]
PRL 97 (2006) 112001
Conclusion:J(-) = 3/2
Extending the Spin Formalism to 3-body Decays
The (1530)0 Spin from c+ → (- +) K+
also mass, width info. amplitude analysis (in progress)
The (1690)0 Spin from c+ → (0KS
0) K+
also mass, width info. amplitude analysis (to be done) (-p+)/(K0) Branching Ratio Limit
(to be done)
12
Study of and
43
NEXT
D0 – D0 Mixing
44
45
Time-Evolution of D0 DecaysD0 can reach the K+ - final state in two ways:1) Doubly-Cabibbo-Suppressed decay2) Mixing to D0bar, followed by Cabibbo-Favoured decay... and interference between them.
Q: How can we distinguish these?A: By the time evolution.
46
• Mixing contours from 2006 PDG– K decay the dominant
mode in the search for mixing
– CP lifetimes sensitive to measuring y
– Semileptonic sensitive to RM= (x2+y2)/2
95% CL allowed
CPV allowed
K=0 assumed
yCP=(0.900.42)%
Summary PDG 2006
~ 0: measured by CLEO
47
Summary
K=0 assumed
~ 0: measured by CLEO
95% CL allowed
CPV allowed
BaBar K
Belle ycp (1)
Updated with new results for this talk
(HFAG plots will be available soon)
• Assuming CP conservation BaBar has found evidence for mixing at 3.9 CL using D0Kdecay mode (384 fb-1)
• ycp by Belle also evidence for mixing at 3.2CL (540 fb-1)– Clear Evidence of Mixing
• Most sensitive measurement of x by Belle (D0Ks)
• A precision measurement of cosneeded 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
Belle ycp
hep-ex/0703036 Submitted To PRL(Belle)hep-ex/0703020 Submitted To PRL (BaBar)0704.1000v1 [hep-ex], Moriond EW/QCD 2007(Belle)
Belle Ks
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
SummaryExperimental 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
x=24.8y~0.1?Bs
0 oscillate very rapidly
Rate first measured in 2006 by CDF and D0
Toy MC
51
52
Best fit
No mixing
1σ
2σ
3σ4σ5σ
Contours include statistical & systematic errors
Fit is inconsistentwith no-mixing at 3.9
Fit Results
RD: (3.03±0.16±0.10)x10-
3 x’2: (-0.22±0.30±0.21)x10-3
y’: (9.7±4.4±3.1)x10-3x'2, y' correlation: -0.94
WS decay time, signal region
data - no mix PDFmix - no mix PDF
Fit to signal & sideband regionsPlot above shows just signal region:
1.843<m<1.883 GeV/c2
0.1445<m< 0.1465 GeV/c2
Evidence for D0-D0 mixing!
53Ratio of WS/RS events clearly increase with time. Mixing signal!