Present status of Present status of CharmCharm

MeasurementsMeasurements

Arantza Oyanguren Arantza Oyanguren ((IFIC –Valencia)IFIC –Valencia)

Outline:Outline:

IntroductionIntroduction Charm fragmentationCharm fragmentation Leptonic decays Leptonic decays Semileptonic decaysSemileptonic decays Mixing and CP violationMixing and CP violation Rare and forbidden decaysRare and forbidden decays Hadronic decaysHadronic decays

Introduction: why charm?Introduction: why charm?Introduction: why charm?Introduction: why charm?

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Vcd

The aim: The aim: find NEW PHYSICS find NEW PHYSICS The role of charm:The role of charm:

1) Overconstraining the UT

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

2) Specific processes with c-hadrons

Charm LandscapeCharm LandscapeCharm LandscapeCharm Landscape

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B-Factories e+e-

(4S)

Charm-”Factories” e+e-(3770)

Hadronic production

BABARBABAR

BELLEBELLE

CLEO-cCLEO-c

BESIIIBESIII

FOCUSFOCUSLHCbLHCbATLAS ATLAS CMS CMS

Charm Data SamplesCharm Data SamplesCharm Data SamplesCharm Data Samples

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0.818 fb-1 @ (3770) ~ 106 D+D- pairs

0.586 fb-1 @ (4170) ~ 106 D*

sDs pairs

BESIII:~ 1 fb-1 @ (3770)( 10fb-1 in 6 years ?)

CLEO-c:

cc ~1.3 nb(4S) (4S)

BELLE:

Physics at charm threshold: (DD)

Physics at (4S) : (BB threshold)

711 fb-1 @ (4S) BaBar: 433 fb-1 @ (4S)

Clean environment: - less background- easy to recontruct all decay products

More statistics ~109 D(s)(*)(**)

More background

DD ~ 6nb

Fragmentation: access to D*, D**, Ds, c, etc…

(530 fb-1)

(1000 fb-1)

Charm FragmentationCharm FragmentationCharm FragmentationCharm Fragmentation

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@ 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…)

pD*/pbeam

D* fragmentation

Present Status:

- 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

The charm fragmentation:- Provide reference data on decay properties- Help in the understanding of the QCD processes (test of models)

JHEP04(2009)082

(103 fb-1)(6 fb-1)

Leptonic Decays:Leptonic Decays:Leptonic Decays:Leptonic Decays:

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Vcd

SM: D= 2.35 x 10-5 : 1: 2.65 (e::)

@ charm threshold:

’’

D+

D-

+K+

-

+

Tag-side:- full reconstruction

- Missing mass squared: Signal-side:

Measurement of decay constants: fD, fDs

fD(s) provides Lattice-QCD validation

CLEO-cCLEO-c

Leptonic Decays:Leptonic Decays:Leptonic Decays:Leptonic Decays:@ B-factories:

cc

D*s-

D

K

+

- Ds (Ds*Ds) reconstruction from all the event including fragmentation particles

521 fb-1

Present Status: - Good agreement between lattice and experiments on fD, not so good (2) on fDs.

- Lattice quite precise.

Ds-

X

- Reconstructed mass:

mr2(DKX

)

arXiv: 1008.4080

CLEO-c () (‘09)

258(11) CLEO-c () (‘09)260(9)

275(20) BELLE () (‘07)

BaBar () (‘10)

Exp. Average (CKM ‘10)

259(10)

260(5)

241(3)

260 (10)

248 (3)

Lattice HPQCD+UKQCD (‘08)

Lattice FNAL+ MILC (‘09)

Lattice HPQCD (‘10)

fDs (MeV)

248 (9) Lattice ETMC (‘10)

207(9)

207 (4)

217(10)

205(10)

fD

Lattice FNAL+ MILC (‘09)

Lattice HPQCD+UKQCD (‘08)

CLEO-c

(MeV)

Lattice ETMC (‘10)

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Semileptonic DecaysSemileptonic DecaysSemileptonic DecaysSemileptonic Decays

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Measurement of form factors f+(q2):

Vcs, Vcd

hadronic effects parameterized by form factors f(q2)

q2=(p+p)2=(pD-px)2

@ charm threshold: -Full reconstruction in the tag side- pion + lepton in the signal side- U = Emiss – |pmiss|

good signal/bkg separation good q2 resolution

CLEO-c

818 pb-1

1) Pseudoscalar: 1 form factor; DP (P=K,)2) Vectorial: 3 form factors; D(s)V (V=K*, ,)

1) D(K or )

’’

D0

D0

-

K+

e+

e -

PRD 80 032005 (‘09)

Present Status:

- Precise measurements of DK and D form factors (BaBar, CLEO-c)

Semileptonic DecaysSemileptonic DecaysSemileptonic DecaysSemileptonic Decays

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@ B-factories:

FNAL/MILC

Preliminary

D

DK

(4S) rest frame

- Partial reconstruction (D* tag) @ BaBar and full reconstraction @ Belle (CLEO-c like) DD00KK--++

DD00KK--++

- New results from CLEO-c on D form factor

- New precise results from Lattice agree with experiment

PRD 76 (2007) 052005

Lattice 2010

Semileptonic DecaysSemileptonic DecaysSemileptonic DecaysSemileptonic Decays

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2) Ds

First evidence of a S-wave component:

70% peaking ()

asymmetryasymmetry

@ charm threshold:@ B factories : DsKKe

Interference with

d depends on q2, v , l , and 2 form factor ratios: rV and rA

-Partial reconstruction method -Also visible the 0+: f0 (980) - Full reconstruction method

K+K-

PRD78 (2008) 051101 (RC)

CLEO-c

PRD 80 (2009) 052009

600 pb-1

214 fb-1

Semileptonic DecaysSemileptonic DecaysSemileptonic DecaysSemileptonic Decays

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2) DK* @ charm threshold:

@ B factories : DKe

d depends on m, q2, v , l , and 2 form factor ratios: rV and r2

-Also measure the suppressed decay De ()

- Full reconstruction method

Also measures the phase of the K S-wave:

Preliminary

Preliminary

Semileptonic DecaysSemileptonic DecaysSemileptonic DecaysSemileptonic Decays

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Present Status:

- Accurate measurements of form factors: DK*Ds

D

0.83 0.15

1.48 0.12

CLEO-c

BaBar BaBar

Comparison with LQCD:

- Lattice lacks precision:

Ds

DK*

Preliminary

Mixing and CP ViolationMixing and CP ViolationMixing and CP ViolationMixing and CP Violation

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Charm mixing: mass and flavor eigenstates are different

The mixing is measured with two parameters: x and y

x=(m1-m2)/

y=(1-2)/2(with =(1+ 2)/2 )

CP Violation in the SM occurs at per mil level and could be found:

In the SM |x| and |y| <10-2

- In the decay (direct)

- In mixing (indirect)

- In the interference between mixing and decay

Weak phase:

468.5 fb-1

Mixing and CP ViolationMixing and CP ViolationMixing and CP ViolationMixing and CP Violation

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First evidence for D0-D0 mixing

Phys.Rev.Lett.98(2007)211802

Wrong sign D0K+- decays:

Amplitude analysis of D0(t) Ks h+h-

(New and most precise result to date)

RS/WS ratio as function of time, extract rotated mixing parameters (x’2, y’).

Mix

ing

ev

ide

nc

e @

3.9

Average decay time as function of Dalitz-plot position allows to get the mixing parameters x and y

@ 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)

384 fb-1

Present Status:

Mixing and CP ViolationMixing and CP ViolationMixing and CP ViolationMixing and CP Violation

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- No CPV point within 1

- Mixing established at 10.2

No mixing point

No CPV point

- Many experimental results:

- SM predictions difficult due to non-perturbative (long-distance) contributions…

?

Present Status:

Rare and forbidden decaysRare and forbidden decaysRare and forbidden decaysRare and forbidden decays

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- Some present results and projections (BESIII with 20fb-1)

Lepton decays (D0+-), GIM suppressed decays (DMeson +-), decays violating Lepton Flavour (De) 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

SummarySummarySummarySummary

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Measurements in the charm sector are important for the CKM picture control of hadronic effects, validation of Lattice QCDIt 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 agreeTheory lacks precision (LQCD for sl decays improving…)

Charm mixing:

Rare decays:

Charm mixing established, need to separate x and y. No CPV at present.What does the SM say?

Sensitivity ~10-6 at CLEO-c, waiting BESIII (~10-8 with 20fb-1) and/or SuperB