Extract the partial rates We can make fits to the partial decay rates to extract

1. l l B n n p p(K) Improved measurements of D meson semileptonic decays to πand K mesons CLEO-c Now CLEO-c full data set + 3-4% theory uncertainties (ρ, η) Δmd,s ~|Vub| Bo Xin, Ian Shipsey, Purdue University, CLEO Collaboration Introduction Form factors as a stringent test of LQCD • The three charge +2/3 quarks and three charge -1/3 quarks change identity via the weak interaction with a probability proportional to the elements of the 3x3 unitary Cabibbo-Kobayashi-Maskawa matrix. These nine elements are related to four fundamental parameters of the standard model of particle physics and must be determined by experiment. • Semileptonic decays are theprincipal process for measuring the CKM matrix elements • Strong interaction effects are confined to the hadronic current and are parameterized by form factors in massless lepton limit • For P to P transitions • The theory must predict the absolute normalization of the form factors: • As |Vcd| and |Vcs| are tightly constrained by the unitarity of the CKM matrix. Measurements of charm semileptonic decay rates and form factors rigorously test the theory (e.g. LQCD) • Validated theory can then be applied to B decays to determine |Vub|, which is the one of the most poorly known CKM matrix elements Form factor measures probability hadron will be formed • Extract the partial rates • We can make fits to the partial decay rates • to extract • (1) normalization f+ (0)|Vcx| • (2) Form factor shape parameters • r1 and r2 (or just r1) for series • Mpole for simple pole • α for modified pole • r for ISGWII from fits to U 1 σ bands (stat and syst) by FNAL-MILC-HPQCD from fits to Mbc Moriond 09 Assuming |Vcs|=0.973340.00023 (CKM unitarity) arXiv:0906.2983 (accepted PRD Jul 22 2009) Suffer from large theory uncertainty HQS 1 σ bands (stat and syst) by FNAL-MILC-HPQCD D D Tagging at 3770 MeV Assuming |Vcd |= 0.22560.0010 (CKM unitarity) Modified pole model used to compare with LQCD Standard D Tags (Tag):One D in the event is fully reconstructed in a hadronic decay mode, the second D decays semileptonically 818 pb-1 @3770 (full data set) World’s largest data set at 3.770 GeV Pure DD, zero additional particles, ~5-6 charged particles per event ~6.6x 105 D0 and ~4.8 x 105 D+ tags reconstructed from ~5.4 x 106 DD events We tag ~20% of the events, compared to ~0.1% of B’s at the Y(4S) α : CLEO-c prefers smaller value for shape parameter than other experiments f+ (0): experiments (1.2%) consistent with LQCD (10%) CLEO-c is most precise. Theoretical precision lags. α : CLEO-c measurements are compatible with LQCD f+ (0): experiments (2.9%) consistent with LQCD (10%). CLEO-c is most precise. Theoretical precision lags. |Vcs | and |Vcd | Results Fits to the U Distributions THEORY UNCERTAINITY REMOVED The data determine |Vcs(d)|f+(0). To extract |Vcs(d)|, we combine the measured |Vcs(d)|f+(0)values using the Becher-Hill parameterization with (FNAL-MILC-HPQCD) forf+(0) • For semileptonic D : U peaks at zero for real semileptonic decays An absolute measurement, independent of the integrated luminosity and number of D mesons in the data sample * * * CLEO-c: the most precise direct determination of |Vcs| * PDG2002 4 of 21 U fits * PDG2002 * PDG2002 4 of 27 U fits CLEO-c: νN remains most precise determination • We perform binned likelihood fits to U distributions in each q2 bin and tag mode • Signal shapes are taken from signal MC, smeared with double Gaussians • Background shapes are taken from MC with all DD and non-DD decays The uncertainties on our results are dominated by uncertainties from LQCD 4 of 42 U fits Summary 4 of 54 U fits DK/πe+ Branching fractions • Goals of CLEO-c semileptonic decay analysis program • To provide validation and calibration data for LQCD and other theoretical approaches thereby enabling theory (especially LQCD) to be applied to B physics (|Vub|). • To measure |Vcs| and |Vcd| with a validated theory • We have perform an analysis using CLEO-c’s final data set to meet these goals • Most precise branching fraction determinations for D Ke+ and D πe+ • Stringent test of LQCD calculations of semileptonic form factors. D Ke+, D πe+ form factors are found to be in general agreement with LQCD. • Best direct measurement of |Vcs|, measured to ±1.1%(experimental) ± 10%(theory). • |Vcd| is measured to ±3.1%(experimental) ± 10%(theory). arXiv:0906.2983 (accepted PRD Jul 22 2009) Precision measurements from BABAR/Belle/CLEO-c. CLEO-c most precise. Theoretical precision lags experiment. Plots by SebastienDescortes-Genon & Ian Shipsey See also talk by Descotres-Genon at joint BABAR-Belle-BESIII-CLEO-c Workshop 11/07, Beijing • Theoretical precision lags. In particular, • CLEO-c measures form factor normalizations for D Ke+, D πe+ to 1% and 3%, respectively, • while LQCD predicts them at 10% level. • We are eagerly awaiting more precise LQCD calculations of semileptonic form factors