Download - Tau-charm physics at B factories
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Stephen L. Olsen, Univ of Hawai’iChinas workshop-2006 June 11-18, Beijing
Tau-charm physics at B
factories
馬 鵬
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• Main purpose: Study CP violation in asymmetric e+e - (4S) BB
• Both experiments have far exceeded their design goals• Approx. 1 ab-1 integrated flux combined
BaBar and Belle
e- (8 GeV/c)
e+ (3.5 GeV/c)
Peak luminosity 1.081034 cm–
2s–1
Integrated luminosity 363 fb–
1
Peak luminosity 1.621034 cm–
2s–1
Integrated luminosity 602 fb–
1
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B Factories are -charm factories
On
~5M charm particles/fb-1
ECM (GeV)
0.89 nb ~2M ’s/fb-1
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-physics at B factories
• M
• Spectral functions– Non-strange & strange
• Rare decays
• Forbidden decays
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m away from threshold
Lafferty Charm 2006
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Precision measurements
79 fb-1
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Strange spectral function
Belle
Path to world-best measurements of |Vus| and ms
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Rare decaysHuge signals for decays
limits on decays
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LFV decays,ℓ-ℓ-
ℓ+, etc
Lafferty Charm 2006
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LFV limits from BaBar & BelleX10-7
Lafferty Charm 2006
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constraints from limits
Lafferty Charm 2006
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constraints from limits
Lafferty Charm 2006
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Future for LFV decays
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Charm physics
•Charmed particle spectroscopy
•Rare decays
•Form-factors
•DDbar mixing
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Sources of charm at B-factories
D
c
d
u
q
D
D
• Continuum– D*-tagged– Recoil tags
• B decays
• Radiative return
c
c
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Old new charmed-strange particles
BaBar BaBar
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BDs DsJ decays are spin filters
BDsDsJ
J=0J=0 J=?; m=0
DsJ(2460)
DsJ(2317)J=0DsJ(2460)J=1
Belle
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P –wave c-s mesons?
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Broad D** states found by Belle
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Masses coincide?
See tak by Dmitrasinovic @ Charm 2006
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New new charmed-strange particles
DsJ(2860)D0K+
BaBar
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Baryons, baryons, baryons..
Signal
c+ sideband
Feeddown from c(2880)+
cc++-- cc
++00 cc++++
ISOTRIPLET!
BelleBelle
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Rare FCNC charm decaysRare FCNC charm decays
18Paul D. Jackson Charm 2006
FCNC decays only occur in loop diagrams in SM:
New physics can introduce new particles into loop Some models increase
BF(cull) to 10-6—10-5
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No signal forFCNC charmdecays foundLimits on yieldsextracted withunbinned likelihood fits
Largest “signal”is ~1.5 in
c+pµ+µ– decays
D+e+e– D+µ+µ–
Ds+Ke+e– D
s+Kµ+µ–
c+pe+e–
c+pµ+µ–
Unblinded Mass DistributionsUnblinded Mass Distributions
Paul D. Jackson Charm 2006 24
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Branching Fraction LimitsBranching Fraction Limits
26Paul D. Jackson Charm 2006
Improved limits in 17 modes, more than order magnitude in 12 modes
(preliminary)
Upper limits on BF (x10-6) at 90% CL
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Ktag
D
mass-constrained vertex fits
e+ e-3.5 GeV 8 GeV
K
K
D0
slow
e/µ
D*-
„inverse“ fit
tag side
Recoil-tagged Charmed mesons
D*
signal side
additional primary mesonsIP
L. Widhalm Charm06
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Form Factors – Comparison with Models
ISGW2 modellattice calculation modified pole model
D0 lD0 l
D0 lD0 l
pole mass (GeV)
Kl 1.82 ± 0.04stat ± 0.03syst
l 1.97 ± 0.08stat ± 0.04syst
simple pole
Kl 0.52 ± 0.08stat ± 0.06syst
l 0.10 ± 0.21stat ± 0.10syst
modified pole(poles fixed at theo. values)
fit results
f+(0)
Kl 0.695 ± 0.007stat ± 0.022syst
l 0.624 ± 0.020stat ± 0.030syst
Belle
L. Widhalm Charm2006
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CLEO-c untagged with v-reconstruction
bcM
Decay Mode - Simple Pole |Vcd| f +(0) mpole
D0 ±e 0.146 ± 0.004 ± 0.003 1.87 ± 0.03 ± 0.01
D± 0e 0.152 ± 0.007 ± 0.004 1.97 ± 0.07 ± 0.02
Decay Mode - Modified Pole |Vcd| f +(0)
D0 ±e 0.142 ± 0.005 ± 0.003 0.37 ± 0.09 ± 0.03
D± 0e 0.151 ± 0.008 ± 0.004 0.12 ± 0.17 ± 0.05
Preliminary
f (q2 ) f (0)
1 q2 mpole2 f (q2 )
f (0)
1 q2 mpole2 1 q2 mpole
2 Simple Pole
ModelModified Pole
Model
D0→-e+ D0→-e+
2q
I Shipsey Charm2006
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DDbar mixing using D*-tags
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DDbar mixing limits
Covered by A Schwartz
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Particles with hidden charm
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Charmonium production in B decays
j=½
j=½
J = 0 or 1
Spectator model says Jcc= 0 or 1 shoulddominate exclusive BK(cc) decays.
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charmonium states
All sub-open-charmthreshold states havebeen identified
Discovered at B factories
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Allowed decays all have Bf~10-3
cK 0.9 x10-3
JK 1.0 x10-3
J/K* 1.4 x10-3
’K 0.7 x10-3
’K* 0.9 x10-3
c0K 0.6 x10-3
c1K 0.7 x10-3
J/K12701.8 x10-3
BK cc(J=2) still not seen
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XYZ particles• X(3872)
– J/ in BKJ/
• Z(3930)– DD in DD
• Y(3940)– J/ in BK J/
• Z(3940)– DD* in e+e- J/ DD*
• Y(4260)– J/ in e+e- J/
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Z(3931) DD at Belle
41 11 evts (5.5)
M=3931 4 2 MeV
208 3 MeV
sin4 (J=2)
Matches well to c2’ expectations
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Z(3931) is most likely the c2’
3931
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X(3940)
e+e-J/ + X
e+e-J/ + DD*
Seen in DD* but not DD; this implies c1’ or c”
but e+e-J/ +c0 not seen
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Is the X(3940) the c”?
3940Mass is about
150 MeV too low
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X(3872)
BK J/
M(J)
’J/
X(3872)J/
S.K. Choi et al PRL 91, 262001
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C=+1 is establishedX(3872)J/ seen in:
Belle
&
M( looks like a (CDF)
X(3872)””J/ seen in Belle
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angular analysis favors 1++ or 2 -+
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X(3872) has no obvious cc assignment
3872
Masswidth way too smallAngular dist. wrong
c is allowed J/ is isospin forbidden
c”
2
MassJ/ way too smallc1’
Masswidth too smallAngular dist wrongc0’
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Y(3940) in BK J/M≈3940 ± 11 MeV≈ 92 ± 24 MeV
S.K. Choi et al. (Belle)PRL94, 182002 (2005)
M(J/) MeV (Y3940 J/ > ~7 MeV (an SUF(3)-violating decay)
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Is the Y(3940) the c1’ ?
Y(3940) J/ enhanced by FSI ?
Y
D
D*FSI
JIt seems strange (to me) that an SU(3)-violating
process can “short out” an SU(3)-allowed process
If the Z(3930) is the c2’ (which seems likely)the Y(3940) mass is too high for the c1’
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Y(4260) /ISR Jee
J/ sideband
Well above DD & DD* threshold but wide & found in a suppressed
mode??
M=4259 8 MeV = 88 23 MeV
B. Aubert et al. (BaBar)hep-ph/0506081
Y(4260)
10.58 GeV
4.26 GeV
not seen in (e+e-hadrons)at Ecm =4.26 GeV
J.Z. Bai et al. (BESII)PRL 88 101802
BES
(e
+e
- h
ad
ron
s)
cc~5nb
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CLEO-c results on the Y(4260)
58 12 pb
PRL 96 162003 (2006)
(Y4260)J/ > ~1.8 MeV>10x higher than what we are used to
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DD** threshold in relation to the Y(4260)
4.26-mD
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Is the Y(4260) a hybrid?Expect distortions of J/ line shape
DD1
No sign ofYDD** “turn-ons”
DD0*0 DD0’0
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Summary• B factories are also -charm factories
• Sensitivity for rare and forbidden LFV decays probably better than at threshold region
• Many discoveries of new (& sometimes unusual) charmed and hidden-charm particles
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謝 謝Thank you