Candidate events are selected by reconstructing a D, called a tag, in several hadronic modes

1. Observation of D+’ e and study of D+e from fits to U from fits to Mbc Inverse of the efficiency matrix Bo Xin, Ian Shipsey, Purdue University, CLEO Collaboration Introduction Observation of D+’ e • D→K/π eν are the gold-plated modes to measure |Vcs| and |Vcd| and to test LQCD • Observations and form factor studies of new modes are desired to gain a complete picture of charm semileptonic decays • Nine exclusive D semileptonic BF’s (56pb-1) + DK/πe • (281pb-1) • Inclusive semileptonic branching fractions (281/pb): • There is room left for new semileptonic modes with small branching fractions. Two of these modes have been found using 281 pb-1 of data • Study of D→η/η’ eν may shed light on the contents of the η/η’ mesons. • The total estimated number of background events for two η decay modes, with statistical uncertainties only, is 0.0425±0.0257 • After including the systematic uncertainties, the total number of background events is 0.0425±0.0284 • According to Poisson statistics, with the uncertainty on the background accounted for with a toy MC experiment, the probability for this background to fluctuate into 5 events is 9.7 x 10-9 , which corresponds to 5.6 standard deviations. • The branching fractions, with asymmetric Poisson errors Precision Measurements: First observation of D’e Normalized to PDG Without applying MC/data correction factors and systematic uncertainties PRL.99: 191801(2007) • Background level is high • Main background: D+→ e+FSR or unassociated noise photons • B(D→η’eν)<3.9x10-4 CLEO’s measurements most precise for ALL modes; 4 modes observed for the first time First observation of D→ηeν PRL.102: 081801(2009) Measurement of the DηeForm factor D Tagging at 3770 MeV • 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 cut on and fit to • For semileptonic D • U peaks at zero for real semileptonic decays • Use the least squares method to fit to the partial rates • Make fits to the partial rates using several form factor parameterizations to extract form factor parameters and branching fraction (First form factor study for D→ηeν) • B(D→ηeν) using this derived method supersedes the global B(D→ηeν), which serves as a cross-check. • When statistics allow (D→ηeν in our case), • The method described above can also be used to obtain partial branching fractions, or equivalently, partial rates in q2 bins. • The theoretically predicted partial rates (P→P transition) 818 pb-1 @3770 Study of dΓ/dq2 in D→ηeν Tagging creates a single D beam of known 4-momentum • Each η decay mode is divided into 3 q2 bins; each plot is for all tag modes combined, due to limited statistics. • Signal (2-tail CB) and background shapes (2nd order polynomial) are taken from signal MC and generic MC. • Each fit has two floating parameters: signal yield and background yield. • Total yield: 110.2±12.7 • (All tag modes/q2 combined fit: 113.0±12.8) Pure DD, zero additional particles, ~5-6 charged particles per event ~4.8 x 105 D+ tags reconstructed from ~2.4 x 106 D+D- events The Global Global Branching Fractions • The branching fraction of the semileptonic decay • The branching fraction determined by tagging is an absolute measurement, independent of the integrated luminosity and number of D mesons in the data sample • In this analysis, using this global • method, we will present • Improved branching fraction measurement for D→ηeν • Observation of D→η’eν and measurement of its branching fraction • Improved upper limit for D→Φeν from fits to U from fits to Mbc First Form Factor Measurement for D→ηeν D+ e branching fraction Distributions of kinematic variables in D+ e • Signal (2-tail CB) and background shapes (2nd order polynomial) are taken from signal MC and generic MC. • Each fit has two floating parameters: signal yield and background yield. Consistent Summary Without applying MC/data correction factors and systematic uncertainties • Br(De): consistent with but more precise than our previous result • First observation of D’e. 5 events consistent with signal, significance: 5.6 sigma • Improved upper limit for D e • First form factor measurement of D+ e Upper limit for D e One event observed in the signal region (-60, 60) MeV. And one in the background region. 90% C.L. interval: (0.00,3.58), corresponds to a 90% C.L. upper limit of 0.8x10-4 (without MC/data corrections) MC/data correction factors applied