1. Present status of Charm Measurements
Arantza Oyanguren
(IFIC –Valencia)

2. Outline:  Introduction  Charm fragmentation  Leptonic decays
 Semileptonic decays
 Mixing and CP violation
 Rare and forbidden decays
 Hadronic decays

3. Introduction: why charm? VII Meeting on B Physics
The aim: find NEW PHYSICS
The role of charm:
1) Overconstraining the UT
Vcd
 Understand the strong interaction:
Hadronic effects in leptonic and
semileptonic decays, fragmentation,
hadronic decays
Help for inputs in B decays
(more sensitive to NP) validating LQCD computations
Search for New Physics in Mixing and
CP violation, rare and forbidden decays
Specific processes with
c-hadrons
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4. VII Meeting on B Physics
Charm Landscape
CLEO-c
BESIII
LHCb
ATLAS
CMS
BELLE
FOCUS
BABAR
B-Factories
e+e-(4S)
Charm-”Factories”
e+e-(3770)
Hadronic
production
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5. VII Meeting on B Physics
Charm Data Samples
Physics at charm threshold: (DD)
Physics at (4S) : (BB threshold)
CLEO-c:
BESIII:
~ 1  (3770)
( 10fb-1 in 6 years ?)
BELLE:
(1000 fb-1)
0.818  (3770)
~ 106 D+D- pairs
711  (4S)
BaBar:
(530 fb-1)
0.586  (4170)
~ 106 D*sDs pairs
433  (4S)
DD ~ 6nb
(4S)
cc ~1.3 nb
More statistics ~109 D(s)(*)(**)
Clean environment:
- less background
- easy to recontruct all decay products
More background
Fragmentation:
access to D*, D**, Ds, c, etc…
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6. VII Meeting on B Physics
Charm Fragmentation
@ the (4S) the c quark hadronizes into D, D*, D**, Ds , baryons…
Their fractions and energetic distributions give infos for the CKM picture
(Ex: D** fractions enter as systematic uncertainties for Vcb, Vub…)
The charm fragmentation:
- Provide reference data on decay properties
- Help in the understanding of the QCD processes (test of models)
(6 fb-1)
Present Status:
(103 fb-1)
- Old measurements from Belle and CLEO-III
(BaBar on the way)
Would like to have all (D, D*, D**, Ds, c, etc…)
fragmentation functions
- Important to separate perturbative and
non-perturbative parts
D* fragmentation
JHEP04(2009)082
pD*/pbeam
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7. Leptonic Decays: Measurement of decay constants: fD, fDs  Vcd
SM: Dln = 2.35 x 10-5 : 1: 2.65 (e::)
Measurement of decay constants: fD, fDs
Vcd 
fD(s) provides Lattice-QCD validation
@ charm threshold: + K+
Tag-side:
- full reconstruction
CLEO-c -
CLEO-c D-
’’ D+ + 
Signal-side:
- Missing mass squared:
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8. VII Meeting on B Physics
Leptonic Decays:
@ B-factories: K
arXiv: X
521 fb-1
- Ds (Ds*Ds) reconstruction from all the event including fragmentation particles D 
- Reconstructed mass: cc 
mr2(DKX) l+
D*s-
Ds- l
Present Status:
258(11)
CLEO-c () (‘09)
Good agreement between lattice and
experiments on fD, not so good (2) on fDs.
Lattice quite precise.
260(9)
CLEO-c () (‘09)
275(20)
BELLE () (‘07)
259(10)
BaBar (l) (‘10)
260(5)
Exp. Average (CKM ‘10)
CLEO-c
207(9)
Lattice HPQCD+UKQCD (‘08)
241(3)
Lattice HPQCD+UKQCD (‘08)
207 (4)
260 (10)
Lattice FNAL+ MILC (‘09)
Lattice FNAL+ MILC (‘09)
217(10)
248 (3)
Lattice HPQCD (‘10)
248 (9)
Lattice ETMC (‘10)
Lattice ETMC (‘10)
205(10)
fDs
(MeV) fD
(MeV)
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9. VII Meeting on B Physics
Semileptonic Decays
Measurement of form factors f+(q2):
hadronic effects
parameterized by form factors f(q2)
q2=(pl+p)2=(pD-px)2
Vcs, Vcd
PRD (‘09)
1) Pseudoscalar: 1 form factor; DP (P=K,)
2) Vectorial: 3 form factors; D(s)V (V=K*, ,)
CLEO-c
1) D(K or ) 
818 pb-1
@ charm threshold: -
Full reconstruction in the tag side
pion + lepton in the signal side
U = Emiss – |pmiss| D0 K+
’’
 good signal/bkg separation
 good q2 resolution D0 e+ e -
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10. VII Meeting on B Physics
Semileptonic Decays
@ B-factories:
Partial reconstruction (D* tag) @ BaBar
and full Belle (CLEO-c like)
D0K-l+
D0K-l+
(4S) rest frame
PRD 76 (2007)
Present Status:
- Precise measurements of
DK and D form factors (BaBar, CLEO-c)
DK
FNAL/MILC
D
- New precise results from
Lattice agree with experiment
Lattice 2010
- New results from CLEO-c on
D  form factor
Preliminary
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11. VII Meeting on B Physics
Semileptonic Decays
2) Ds
@ charm threshold:
@ B factories : DsKKe
- Full reconstruction method
-Partial reconstruction method
-Also visible the 0+: f0 (980)
214 fb-1
d depends on
q2,  v , l , 
and 2 form factor ratios:
rV and rA
CLEO-c
  K+K-
600 pb-1
70% peaking ()
PRD78 (2008) (RC)
asymmetry
Interference with 
PRD 80 (2009)
First evidence of a S-wave component:
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12. VII Meeting on B Physics
Semileptonic Decays
@ charm threshold:
2) DK*
- Full reconstruction method
@ B factories : DKe
Also measure the suppressed
decay De ()
Preliminary
d depends on
m, q2,  v , l , 
and 2 form factor ratios:
rV and r2
Preliminary
Also measures the phase
of the K S-wave:
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13. VII Meeting on B Physics
Semileptonic Decays
Present Status:
- Accurate measurements of form factors:
- Lattice lacks precision:
Ds
DK*
Comparison with LQCD:
Ds
Preliminary
D
0.83  0.15
1.48 0.12
DK*
CLEO-c
BaBar
BaBar
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14. Mixing and CP Violation VII Meeting on B Physics
Charm mixing:
mass and flavor eigenstates are different
The mixing is measured with two parameters: x and y
x=(m1-m2)/
(with =(1+ 2)/2 )
y=(1-2)/2
In the SM |x| and |y| <10-2
CP Violation in the SM occurs at per mil level and could be found:
- In the decay (direct)
- In mixing (indirect)
Weak phase:
- In the interference between mixing and decay
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15. Mixing and CP Violation VII Meeting on B Physics
@ B factories:
Time dependent mesurements:
- Select D0 mesons from D*+D0+ (tags flavour)
- m=mD*+ - mD0 to supress bkg.
- Measure the decay time (t ~ 0.2 ps)
First evidence for D0-D0 mixing
Wrong sign D0K+- decays:
RS/WS ratio as function of time,
extract rotated mixing parameters (x’2, y’).
Amplitude analysis of D0(t)  Ks h+h-
Average decay time as function of Dalitz-plot position allows to get the mixing parameters x and y
384 fb-1
(New and most precise result to date)
Mixing 3.9s
468.5 fb-1
Phys.Rev.Lett.98(2007)211802
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16. Mixing and CP Violation VII Meeting on B Physics
Present Status:
- Many experimental results:
- Mixing established at 10.2
- No CPV point within 1
No CPV point ?
No mixing point
- SM predictions difficult due to non-perturbative (long-distance) contributions…
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17. Rare and forbidden decays VII Meeting on B Physics
Lepton decays (D0+-), GIM suppressed decays (DMeson +-),
decays violating Lepton Flavour (De) or Lepton Number (D+Meson ++)
Very suppressed (B < 10-6), ultra-suppressed or forbidden in the SM
New Physics could enhance the rates through virtual non-standard particles
Present Status:
Some present results and projections
(BESIII with 20fb-1)
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18. VII Meeting on B Physics
Summary
Measurements in the charm sector are important for the CKM picture 
control of hadronic effects, validation of Lattice QCD
It can also give signs of New Physics
Leptonic decays:
theory and experiment agree on D, not so well on Ds (2)
Some results from LQCD more accurate than experiment (BESIII?)
Semileptonic decays:
Experimental results from B-Factories and CLEO-c agree
Theory lacks precision (LQCD for sl decays improving…)
Charm mixing:
Charm mixing established, need to separate x and y. No CPV at present.
What does the SM say?
Rare decays:
Sensitivity ~10-6 at CLEO-c, waiting BESIII (~10-8 with 20fb-1) and/or SuperB
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