D. Hertz

Improved measurement of absolute branching fraction of D{sub s}{sup +}{yields}{tau}{sup +}{nu}{sub {tau}}

We have studied the leptonic decay D{sub s}{sup +}{yields}{tau}{sup +}{nu}{sub {tau}}, via the decay channel {tau}{sup +}{yields}e{sup +}{nu}{sub e}{nu}{sub {tau}}, using a sample of tagged D{sub s}{sup +} decays collected near the D{sub s}*{sup {+-}}D{sub s}{sup {+-}} peak production energy in e{sup +}e{sup -} collisions with the CLEO-c detector. We obtain B(D{sub s}{sup +}{yields}{tau}{sup +}{nu}{sub {tau}})=(5.30{+-}0.47{+-}0.22)% and determine the decay constant f{sub D{sub s}}=(252.5{+-}11.1{+-}5.2) MeV, where the first uncertainties are statistical and the second are systematic.

First model-independent determination of the relative strong phase between D{sup 0} and D{sup 0}{yields}K{sub S}{sup 0}{pi}{sup +}{pi}{sup -} and its impact on the CKM angle {gamma}/{phi}{sub 3} measurement

We exploit the quantum coherence between pair-produced D 0 and D 0 in Ψ(3770) decays to make a first determination of the relative strong phase differences between D 0 → K 0 S π + π - and D 0 → K 0 S π + π - which are of great importance in determining the Cabibbo-Kobayashi-Maskawa angle γ/Φ 3 in B - → D 0 (D 0 )K - decays. Using 818 pb -1 of e + e - collision data collected with the CLEO-c detector at E cm = 3.77 GeV, we employ a binned Dalitz-plot analysis of K 0 S π + π - and K 0 L π + π - decays recoiling against flavor-tagged, CP-tagged, and K 0 S π + π - -tagged events to determine these strong phase differences.

Determination of the D{sup 0}{yields}K{sup +}{pi}{sup -} relative strong phase using quantum-correlated measurements in e{sup +}e{sup -}{yields}D{sup 0}D{sup 0} at CLEO

We exploit the quantum coherence between pair-produced D{sup 0} and D{sup 0} in {psi}(3770) decays to study charm mixing, which is characterized by the parameters x and y, and to make a first determination of the relative strong phase {delta} between doubly Cabibbo-suppressed D{sup 0}{yields}K{sup +}{pi}{sup -} and Cabibbo-favored D{sup 0}{yields}K{sup +}{pi}{sup -}. We analyze a sample of 1.0x10{sup 6} D{sup 0}D{sup 0} pairs from 281 pb{sup -1} of e{sup +}e{sup -} collision data collected with the CLEO-c detector at E{sub cm}=3.77 GeV. By combining CLEO-c measurements with branching fraction input and time-integrated measurements of R{sub M}{identical_to}(x{sup 2}+y{sup 2})/2 and R{sub WS}{identical_to}{gamma}(D{sup 0}{yields}K{sup +}{pi}{sup -})/{gamma}(D{sup 0}{yields}K{sup +}{pi}{sup -}) from other experiments, we find cos{delta}=1.03{sub -0.17}{sup +0.31}{+-}0.06, where the uncertainties are statistical and systematic, respectively. In addition, by further including external measurements of charm mixing parameters, we obtain an alternate measurement of cos{delta}=1.10{+-}0.35{+-}0.07, as well as xsin{delta}=(4.4{sub -1.8}{sup +2.7}{+-}2.9)x10{sup -3} and {delta}=(22{sub -12-11}{sup +11+9}) deg.

Observation of {psi}(3770){yields}{pi}{pi}J/{psi} and Measurement of {gamma}{sub ee}[{psi}(2S)]

We observe signals for the decays psi(3770) --> XJ/psi from data acquired with the CLEO detector operating at the CESR e+ e- collider with square root of s = 3773 MeV. We measure the following branching fractions Beta(psi(3770) --> XJ/psi and significances: (189 +/- 20 +/- 20) x 10(-5) (11.6sigma) for X = pi+ pi-, (80 +/- 25 +/- 16) x 10(-5) (3.4sigma) for X = pi0 pi0, and (87 +/- 33 +/- 22) x 10(-5) (3.5sigma) for X = eta, where the errors are statistical and systematic, respectively. The radiative return process e+ e- --> gamma psi(2S) populates the same event sample and is used to measure Gamma ee[psi(2S)] = (2.54 +/- 0.03 +/- 0.11) keV.

Observation of the h{sub c}({sup 1}P{sub 1}) State of Charmonium

The h{sub c}({sup 1}P{sub 1}) state of charmonium has been observed in the reaction {psi}(2S){yields}{pi}{sup 0}h{sub c}{yields}({gamma}{gamma})({gamma}{eta}{sub c}) using 3.08x10{sup 6} {psi}(2S) decays recorded in the CLEO detector. Data have been analyzed both for the inclusive reaction, where the decay products of the {eta}{sub c} are not identified, and for exclusive reactions, in which {eta}{sub c} decays are reconstructed in seven hadronic decay channels. We find M(h{sub c})=3524.4{+-}0.6{+-}0.4 MeV which corresponds to a hyperfine splitting {delta}M{sub hf}(1P){identical_to} -M({sup 1}P{sub 1})=+1.0{+-}0.6{+-}0.4 MeV, and B({psi}(2S){yields}{pi}{sup 0}h{sub c})xB(h{sub c}{yields}{gamma}{eta}{sub c})=(4.0{+-}0.8{+-}0.7)x10{sup -4}.