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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 ArantzaOyanguren (IFIC –Valencia)
Outline: Introduction Charmfragmentation Leptonicdecays Semileptonicdecays Mixing and CP violation Rare and forbiddendecays Hadronicdecays
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
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
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
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
LeptonicDecays: SM: Dln= 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
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
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; DP (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
SemileptonicDecays @ B-factories: • Partial reconstruction (D* tag) @ BaBar • and full reconstraction @ Belle (CLEO-c like) D0K-l+ D0K-l+ (4S) rest frame PRD 76 (2007) 052005 Present Status: DK - Precise measurements of DK 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
SemileptonicDecays 2) Ds @ charmthreshold: @ B factories : DsKKe - 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
SemileptonicDecays @ charmthreshold: 2) DK* - Full reconstruction method @ B factories : DKe • Also measure the suppressed • decay De () 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
SemileptonicDecays Present Status: - Accurate measurements of form factors: - Lattice lacks precision: Ds DK* Comparison with LQCD: Ds Preliminary DK* CLEO-c BaBar BaBar 13 VII Meeting on B Physics ArantzaOyanguren
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
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 D0K+- 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
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
Rare and forbiddendecays • 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 Present Status: • Some present results and projections • (BESIII with 20fb-1) 17 VII Meeting on B Physics ArantzaOyanguren
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