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Present status of Charm Measurements

Present status of Charm Measurements. Arantza Oyanguren. ( IFIC –Valencia). Outline :.  Introduction  Charm fragmentation  Leptonic decays  Semileptonic decays  Mixing and CP violation  Rare and forbidden decays  Hadronic decays. Introduction : why charm ?.

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Present status of Charm Measurements

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

  2. Outline:  Introduction  Charmfragmentation  Leptonicdecays  Semileptonicdecays  Mixing and CP violation  Rare and forbiddendecays  Hadronicdecays

  3. Introduction: whycharm? The role of charm: Theaim: find NEW PHYSICS Vcd 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 • Specific processes with • c-hadrons 3 VII Meeting on B Physics ArantzaOyanguren

  4. CharmLandscape CLEO-c BESIII LHCb ATLAS CMS BELLE FOCUS BABAR Charm-”Factories” e+e-(3770) B-Factories e+e-(4S) Hadronic production 4 VII Meeting on B Physics ArantzaOyanguren

  5. Charm Data Samples Physics at (4S) : (BB threshold) Physics at charm threshold: (DD) CLEO-c: BESIII: ~ 1 fb-1 @  (3770) ( 10fb-1 in 6 years ?) BELLE: (1000 fb-1) 0.818 fb-1 @  (3770) ~ 106 D+D- pairs 711 fb-1 @  (4S) BaBar: (530 fb-1) 0.586 fb-1 @  (4170) ~ 106 D*sDs pairs 433 fb-1 @  (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… 5 VII Meeting on B Physics ArantzaOyanguren

  6. CharmFragmentation @ 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) Present Status: (6 fb-1) (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 6 VII Meeting on B Physics ArantzaOyanguren

  7. LeptonicDecays: SM: Dln= 2.35 x 10-5 : 1: 2.65 (e::) Measurement of decayconstants: fD,fDs  Vcd fD(s) providesLattice-QCD validation @ charmthreshold: + K+ Tag-side: - full reconstruction CLEO-c - CLEO-c D- ’’ D+ +  Signal-side: - Missingmasssquared: 7 VII Meeting on B Physics ArantzaOyanguren

  8. LeptonicDecays: arXiv: 1008.4080 K @ B-factories: X 521 fb-1 - Ds (Ds*Ds) reconstructionfromalltheeventincludingfragmentationparticles D  cc - Reconstructedmass:  D*s- l+ mr2(DKX) Ds- l Present Status: CLEO-c () (‘09) 258(11) • Good agreement between lattice and • experiments on fD, not so good (2) on fDs. • Lattice quite precise. 260(9) CLEO-c () (‘09) BELLE () (‘07) 275(20) BaBar (l) (‘10) 259(10) 260(5) Exp. Average (CKM ‘10) CLEO-c 207(9) Lattice HPQCD+UKQCD (‘08) 241(3) Lattice HPQCD+UKQCD (‘08) 207 (4) Lattice FNAL+ MILC (‘09) 260 (10) Lattice FNAL+ MILC (‘09) 217(10) Lattice HPQCD (‘10) 248 (3) Lattice ETMC (‘10) 248 (9) Lattice ETMC (‘10) 205(10) fDs (MeV) fD (MeV) 8 VII Meeting on B Physics ArantzaOyanguren

  9. SemileptonicDecays Measurement of formfactorsf+(q2): hadronic effects parameterized by form factors f(q2) q2=(pl+p)2=(pD-px)2 Vcs, Vcd PRD 80 032005 (‘09) 1) Pseudoscalar: 1 form factor; DP (P=K,) 2) Vectorial: 3 formfactors; D(s)V (V=K*, ,) CLEO-c 1) D(K or)  818 pb-1 @ charmthreshold: - • 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 - 9 VII Meeting on B Physics ArantzaOyanguren

  10. SemileptonicDecays @ B-factories: • Partial reconstruction (D* tag) @ BaBar • and full reconstraction @ Belle (CLEO-c like) D0K-l+ D0K-l+ (4S) rest frame PRD 76 (2007) 052005 Present Status: DK - Precise measurements of DK and D form factors (BaBar, CLEO-c) FNAL/MILC D - New precise results from Lattice agree with experiment Lattice 2010 Preliminary - New results from CLEO-c on D  form factor 10 VII Meeting on B Physics ArantzaOyanguren

  11. SemileptonicDecays 2) Ds @ charmthreshold: @ B factories : DsKKe - Full reconstruction method -Also visible the 0+: f0 (980) -Partial reconstruction method 214 fb-1 d dependson q2,v , l , and 2 form factor ratios: rVandrA CLEO-c   K+K- 600 pb-1 70% peaking () PRD78 (2008) 051101 (RC) asymmetry Interference with  PRD 80 (2009) 052009 Firstevidence of a S-wave component: 11 VII Meeting on B Physics ArantzaOyanguren

  12. SemileptonicDecays @ charmthreshold: 2) DK* - Full reconstruction method @ B factories : DKe • Also measure the suppressed • decay De () Preliminary d dependson m, q2,v , l , and 2 form factor ratios: rVandr2 Preliminary Also measures the phase of the K S-wave: 12 VII Meeting on B Physics ArantzaOyanguren

  13. SemileptonicDecays Present Status: - Accurate measurements of form factors: - Lattice lacks precision: Ds DK* Comparison with LQCD: Ds Preliminary DK* CLEO-c BaBar BaBar 13 VII Meeting on B Physics ArantzaOyanguren

  14. Mixing and CP Violation 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) Weakphase: - In the interference between mixing and decay 14 VII Meeting on B Physics ArantzaOyanguren

  15. Mixing and CP Violation @ B factories: Time dependent mesurements: - Select D0 mesons from D*+D0+ (tagsflavour) - 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 evidence @ 3.9s 468.5 fb-1 Phys.Rev.Lett.98(2007)211802 15 VII Meeting on B Physics ArantzaOyanguren

  16. Mixing and CP Violation 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… 16 VII Meeting on B Physics ArantzaOyanguren

  17. Rare and forbiddendecays • 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) 17 VII Meeting on B Physics ArantzaOyanguren

  18. 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 18 VII Meeting on B Physics ArantzaOyanguren

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