Bo XinD  K/π e + and Vcs and Vcd at CLEO-c 12/20/2008 Study of and measurement of V cs and V cd at CLEO-c Study of D  K/πe + and measurement of V cs and V cd at CLEO-c  Introduction  Reconstruction techniques  Results: branching fractions, form factors, V cs and V cd  Projections  Summary Bo Xin Purdue University CLEO collaboration Lake Louise Winter Institute, Feb , 2008 K-K-  - - e+e+ K+K+

Bo XinD  K/π e + and Vcs and Vcd at CLEO-c 22/20/2008 Semileptonic decays are an excellent laboratory to study Introduction Weak Physics QCD Physics ** Gold-plated modes are P  P semileptonic transitions as they are the simplest modes for both theory and experiment: – Cabibbo favored : – Cabibbo suppressed :  Assuming theoretical calculations of form factors, we can extract |V cs | and |V cd |  Since |V cs | and |V cd | are tightly constrained by unitarity, we can check theoretical calculations of the form factors  Tested theory can then be applied to B semileptonic decays to extract |V ub |.

Bo XinD  K/π e + and Vcs and Vcd at CLEO-c 32/20/2008 The CLEO-c detector and data sample SVX CLEO III  p/p = 0.6% at 800 MeV/c  E/E = 2% at 1 GeV, 5% at 100 MeV 5% at 100 MeV 93% coverage (charged and neutral) Excellent electron and particle ID CLEO-c Advantages at  (3770) –Pure, no additional particles –Low multiplicity –High tagging efficiency CLEO has world’s largest data set at GeV Today’s results (281/pb) 30X MARK III 15X BES II

Bo XinD  K/π e + and Vcs and Vcd at CLEO-c 42/20/2008 Analysis Technique  Candidate events are selected by reconstructing a D, called a tag, in several hadronic modes  Then we reconstruct the semileptonic decay in the system recoiling from the tag.  Two key variables in the reconstruction of a tag:  Define  The absolute branching fraction is Tagging creates a single D beam of known 4-momentum

Bo XinD  K/π e + and Vcs and Vcd at CLEO-c 52/20/2008 Pure DD, zero additional particles, ~5-6 charged particles per event ~3.1x 10 5 D 0 and ~1.6 x 10 5 D + tags Reconstructed from ~1.8 x 10 6 DD events We tag ~25% of the events, compared to ~0.1% of B’s at the Y(4S) D tagging at CLEO-c (281/pb of Data) World’s largest data set at GeV

Bo XinD  K/π e + and Vcs and Vcd at CLEO-c 62/20/2008 Reconstruction of Semileptonic Decays S/N ~ 40/1, Compared to Belle 282/fb – 1000xCLEO-c ~220 signal events, S/N ~ 4/1 S/N ~ 300/1, Compared to Belle 282/fb – 1000xCLEO-c ~2700 signal events, S/N ~ 20/1  Extract yields from U distributions and measure branching fractions with multiple tag modes separately and combined  Study form factors and CKM matrix elements using efficiency- corrected decay rate distributions 295     84 PRELIMINARY

Bo XinD  K/π e + and Vcs and Vcd at CLEO-c 72/20/2008 Neutrino Reconstruction (Untagged) Larger signal yields, also larger backgrounds  Hermeticity and excellent resolution of the CLEO-c detector  Simultaneously fit M bc distributions of the 4 signal modes in 5 q 2 bins to extract d(BF)/dq 2 and integrate to get branching fractions.

Bo XinD  K/π e + and Vcs and Vcd at CLEO-c 82/20/2008 D  K/πe + Branching fractions Isospin Invariance: (From Tagged analysis) CLEO-c Tagged/untagged consistent, 40% overlap, DO NOT AVERAGE CLEO-c most precise! Theoretical precision lags experiment

Bo XinD  K/π e + and Vcs and Vcd at CLEO-c 92/20/2008 q 2 resolutions and Raw q 2 distributions D 0 →K - e + ν D0→π-e+νD0→π-e+ν ~700 events S/B ~40/1 CLEOIII(Y(4S)):  q 2 ~ 0.4 GeV 2 CLEO-c(  (3770)):  q 2 ~ 0.012GeV 2  q2 ~ 0.012GeV 2  q2 ~ 0.011GeV 2 Raw q 2 distributionq 2 resolution background in blue ~7000 events S/B > 300/1 D0→π-e+νD0→π-e+ν D 0 →K - e + ν  Excellent q 2 resolution and S/B ratio  To find the absolute decay rate, need to subtract background and apply efficiency corrections. background in blue PRELIMINARY

Bo XinD  K/π e + and Vcs and Vcd at CLEO-c 102/20/2008 Fit to the Absolute Decay rates Modified Pole (BK) Model Simple Pole Model Hill Series parameterization Fit to Simple Pole Model Shown PRELIMINARY

Bo XinD  K/π e + and Vcs and Vcd at CLEO-c 112/20/2008 Form factors as a stringent test of LQCD Removing the kinematic terms reveals the form factor Assuming V cs =  (CKM unitarity) FNAL-MILC-HPQCD (Curve courtesy Andreas Kronfeld) Modified Pole (BK) Model shown

Bo XinD  K/π e + and Vcs and Vcd at CLEO-c 122/20/2008 Simple Pole Model D → K e + ν CLEO-c has 1 st measurements of M pole for D + Important consistency check! My average

Bo XinD  K/π e + and Vcs and Vcd at CLEO-c 132/20/2008 Modified Pole (BK) Model D → π e + ν 0.32(5) BK parameterization α~1.75 CLEO-c values > 10σ away Physical basis of BK model not supported Compatible Consistent For D → K e + ν, CLEO-c α values > 27σ away from BK physical value, LQCD precision (10%) lags experiments (2%) ! LQCD precision(10%) lags experiments (4%) My average 0.634(18)(9)(8)

Bo XinD  K/π e + and Vcs and Vcd at CLEO-c 142/20/2008 Becher-Hill series parameterization Both Linear “series(2)” and quadratic “series(3)” parameterization describes data well Quadratic “series(3)” a 2 not well-determined with current statistics As data does not support physical basis for the pole & modified pole models, the model independent Becher-Hill series parameterization is used for |V cx |. Dashed lines show 1 σ region

Bo XinD  K/π e + and Vcs and Vcd at CLEO-c 152/20/2008 V cs and V cd Results Tagged/ untagged consistent, 40% overlap DO NOT AVERAGE Combine measured |V cx |f + (0) values using Becher-Hill parameterization with (FNAL_MILC-HPQCD) for f + (0) Decay Mode|V cx | ± (stat) ± (syst) ± (theory) PDG D   e  (tagged) ± ± ± ± (  interactions) D   e  (untagged) ± ± ± D  Ke  (tagged) ± ± ± ± 0.16 (excl. sl. Width excluding CLEO/BES) W  cs tagged D  Ke  (untagged) ± ± ± Expt. uncertainties Vcs <2% Vcd~4% Theory 10% CLEO-c: Best determination of Vcs, and Vcd in good agreement with PDG

Bo XinD  K/π e + and Vcs and Vcd at CLEO-c 162/20/2008 Projections with 818/pb data 281/pb 818/pb 281/pb 818/pbNOT CLEO-c official  Statistical uncertainties will be reduced by a factor of  Most systematic uncertainties are being reevaluated. some are expected to be reduced. I. Shipsey Aspen 2008 Winter Conference

Bo XinD  K/π e + and Vcs and Vcd at CLEO-c 172/20/2008 Summary  Most precise B( D  K e + ) and B(D   e + ).  Most precise measurements of f + (0) and shape for D   e +.  Best direct measurement of |V cs |.  Most precise determination of |V cd | from semileptonic decays.  More stringent tests of theory for D  K/  e + f + (0) and shape.  Reduced uncertainties on |V cs | and |V cd |. What we have achieved (281/pb) What we are going to achieve (818/pb) We are eagerly awaiting more precise LQCD calculations of semileptonic form factors.