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Publications and source records attributed to CLEO Collaboration.
A precision measurement of the D^0 meson mass has been made using ~281 pb-1 of e+e- annihilation data taken with the CLEO-c detector at the psi(3770) resonance. The exclusive decay D^0 -> (Ks phi) has been used to obtain M(D^0)=1864.847+-0.150(stat)+-0.095(syst) MeV. This corresponds to M(D^0 D^*0)=3871.81+-0.36 MeV, and leads to a well-constrained determination of the binding energy of the proposed (D^0 D^*0) molecule X(3872), E_b=0.6+-0.6 MeV.
We present an improved measurement of the $η'$ meson energy spectrum in $Υ(1S)$ decays, using 1.2 fb^{-1} of data taken at the $Υ(1S)$ center-of-mass energy with the CLEO III detector. We compare our results with models of the $η'$ gluonic form factor that have been suggested to explain the unexpectedly large $B\to η'X_s$ rate. Models based on perturbative QCD fail to fit the data for large $η'$ energies, and thus an explanation outside the realm of the Standard Model or an improved understanding of non-perturbative QCD effects may be needed to account for this large rate.
We present measurements of the inclusive branching fractions for the decays D^+ -> X e^+ nu_e and D^0 -> X e^+ nu_e, using 281 pb^-1 of data collected on the psi(3770) resonance with the CLEO-c detector. We find Br(D^0 ->Xe^+ν_e) = (6.46 \pm 0.17 \pm 0.13)% and Br((D^+ -> Xe^+nu_e) = (16.13 \pm 0.20 \pm 0.33)%. Using the known D meson lifetimes, we obtain the ratio Gamma{D^+}^sl/Gamma_{D^0}^sl= 0.985\pm 0.028\pm 0.015, confirming isospin invariance at the level of 3%. The positron momentum spectra from D^+ and D^0 have consistent shapes.
Using 5.63 pb^-1 of data accumulated at the psi(2S) resonance with the CLEO III and CLEO-c detectors corresponding to 3.08 million psi(2S) decays, a search is performed for the decay psi(2S) -> eta_c pi^+pi^-pi^0 to test a theoretical prediction based upon the assumption that the c \bar c pair in the psi(2S) does not annihilate directly into three gluons but rather survives before annihilating. No signal is observed, and a combined upper limit from six eta_c decay modes is determined to be B(psi(2S) -> eta_c pi^+pi^-pi^0) < 1.0 x 10^-3 at 90% C.L. This upper limit is about an order of magnitude below the theoretical expectation.
Using 13.3 fb^-1 of e+e- collision data taken in the Upsilon(1S-4S) region with the CLEO III detector at the CESR collider, a search has been made for the new resonance Y(4260) recently reported by the BaBar Collaboration. The production of Y(4260) in initial state radiation (ISR), and its decay into pi+pi-J/psi are confirmed. A good quality fit to our data is obtained with a single resonance. We determine M(Y(4260))=(4284+17-16(stat)+-4(syst)) MeV/c^2, Gamma(Y(4260))=(73+39-25(stat)+-5(syst)) MeV/c^2, and Gamma_ee(Y(4260))xBr(Y(4260)->pi+pi-J/psi)=(8.9+3.9-3.1(stat)+-1.9(syst)) eV/c^2.
We present a measurement of the branching fraction for the doubly-Cabibbo-suppressed decay D+ to K+ pi0, using 281 pb-1 of data accumulated with the CLEO-c detector on the psi(3770) resonance. We find B(D+ to K+ pi0) = (2.28 +- 0.36 +- 0.15 +- 0.08) times 10^{-4}, where the first uncertainty is statistical, the second is systematic, and the last error is due to the uncertainty in the reference mode branching fraction.
Knowledge of the Bs decay fraction of the Y(5S) resonance, fs, is important for Bs meson studies at the Y(5S) energy. Using a data sample collected by the CLEO III detector at CESR consisting of 0.423/fb on the Y(5S) resonance, 6.34/fb on the Y(4S) and 2.32/fb in the continuum below the Y(4S), we measure B(Y(5S) -> phi X)=(13.8 +/- 0.7 {+2.3}{-1.5})% and B(Y(4S) -> phi X) = (7.1 +/- 0.1 +/-0.6)%; the ratio of the two rates is (1.9 +/- 0.1 {+0.3}{-0.2}). This is the first measurement of the phi meson yield from the Y(5S). Using these rates, and a model dependent estimate of B(Bs -> phi X), we determine fs = (24.6 +/- 2.9 {+11.0}{-5.3})%. We also update our previous independent measurement of fs made using the inclusive Ds yields to now be (16.8 +/- 2.6 {+6.7}{-3.4)%, due to a better estimate of the number of hadronic events. We also report the total Y(5S) hadronic cross section above continuum to be sigma(e^+e^- -> Y(5S))=(0.301 +/- 0.002 +/- 0.039) nb. This allows us to extract the fraction of B mesons as (58.9+/-10.0+/-9.2)%, equal to 1-fs. averaging the three methods gives a model dependent result of fs=(21 {+6}{-3})%.
We measure the inclusive branching fractions of charm mesons into three mesons with large s-anti-s content, namely the eta, eta' and phi. Data were accumulated with the CLEO-c detector. For D0 and D+ rates, we use 281/pb taken on the psi(3770) resonance, and for Ds+ rates, we use 195/pb taken at 4170 MeV. We find that the production rates of these particles are larger in Ds+ decays than in D0 and D+ decays. The phi rate, in particular, is 15 times greater. These branching fractions can be used to measure Bs yields either at the Upsilon(5S) resonance or at hadron colliders.
We present model independent measurements of the helicity basis form factors in the decay D+ -> K- pi+ e+ nu_e obtained from about 2800 decays reconstructed from a 281 pb^{-1} data sample collected at the psi(3770) center-of-mass energy with the CLEO-c detector. We confirm the existence of a previously observed spin-zero K- pi+ component interfering with the K*0bar amplitude. We see no evidence for additional d- or f-wave contributions.
Due to the quantum correlation between the pair-produced D0 and D0bar from the decay of the psi(3770), the time-integrated single and double tag decay rates depend on charm mixing amplitudes, doubly-Cabibbo-suppressed amplitudes, and the relative strong phase delta between D0 and D0bar decays to identical final states. Using 281 pb^{-1} collected with the CLEO-c detector on the psi(3770) resonance, we measure the absolute branching fractions of D0 decays to hadronic flavored states, CP eigenstates, and semileptonic final states to determine the relative strong phase, cos delta, of the K- pi+ final state and to limit the mixing amplitude y. The results presented in this document are preliminary.
Using data taken with the CLEO III detector at the Cornell Electron Storage Ring, we have investigated the direct photon spectrum in the decays Upsilon(1S) -> gggamma, Upsilon(2S) -> gggamma, Upsilon}(3S) -> gggamma. The latter two of these are first measurements. Our analysis procedures differ from previous ones in the following ways: a) background estimates (primarily from pi^0 decays are based on isospin symmetry rather than a determination of the pi^0 spectrum, which permits measurement of the Upsilon(2S) and Upsilon(3S) direct photon spectra without explicit corrections for pi^0 backgrounds from, e.g., chi_bJ states, b) we estimate the branching fractions with a parametrized functional form (exponential) used for the background, c) we use the high-statistics sample of Upsilon(2S) -> pi+ pi- Upsilon(1S) to obtain a tagged-sample of Upsilon(1S) -> gamma + X events, for which there are no QED backgrounds. We determine values for the ratio of the inclusive direct photon decay rate to that of the dominant three-gluon decay Upsilon -> ggg (R_gamma=B(gggamma)/B(ggg)) to be: R_gamma(1S)=(2.70+/-0.01+/-0.13+/-0.24)%, R_gamma(2S)=(3.18+/-0.04+/-0.22+/-0.41)%, and R_gamma(3S)=(2.72+/-0.06+/-0.32+/-0.37)%, where the errors shown are statistical, systematic, and theoretical model-dependent, respectively. Given a value of Q^2, one can estimate a value for the strong coupling constant alpha_s(Q^2) from R_gamma.
Motivated by concerns regarding possible two-body contributions to the recently-measured inclusive $Υ$(nS)$\toγ+X$ direct photon spectrum, we report on a preliminary new study of exclusive radiative decays of the $Υ$ resonances into two-body final states ${\cal R}γ$, with ${\cal R}$ some resonant hadronic state decaying into four or more charged particles. Such two-body processes are not explicitly addressed in the extant theoretical frameworks used to calculate the inclusive direct photon spectrum. Using data collected from the CLEO III detector at the Cornell Electron Storage Ring, we present upper limits for such $Υ({\rm 1S})$, $Υ({\rm 2S})$, and $Υ({\rm 3S})$ two-body decays as a function of the recoil mass $M_{\cal R}$. Additionally, we place upper limits on the cross-section for ${\cal R}$ production via radiative return for center-of-mass energies just below the $Υ({\rm 1S})$, $Υ({\rm 2S})$, and $Υ({\rm 3S})$ energies. The results presented in this document are preliminary.
We present preliminary measurements of D to K^0_L pi and D to K^0_S pi branching fractions using 281 pb^{-1} of psi(3770) data at the CLEO-c experiment. We find that BF(D^0 to KS pi^0) is larger than BF(D^0 to KL pi^0), with an asymmetry of R(D^0) = 0.122 +- 0.024 +- 0.030. For BF(D^+ to KS pi^+) and BF(D^+ to KL pi^+), we observe no measureable difference; the asymmetry is R(D^+) = 0.030 +- 0.023 +- 0.025. Under reasonable theoretical assumptions, these measurements imply a value for the D^0 to K^+- pi^-+ strong phase that is consistent with zero. The results presented in this document are preliminary.
We present a measurement of the branching fraction for the doubly-Cabibbo-suppressed decay D+ to K+ pi0, using 281 pb-1 of data accumulated with the CLEO-c detector on the psi(3770) resonance. We find B(D+ to K+ pi0) = (2.25 +- 0.36 +- 0.15 +- 0.07) times 10^{-4}, where the first uncertainty is statistical, the second is systematic, and the last error is due to the uncertainty in the reference mode. The results presented in this document are preliminary.
We report preliminary measurements of absolute hadronic branching fractions of Ds mesons determined using a double tag technique. These measurements are from 195 pb^{-1} of e+e- collisions recorded at center of mass energies near 4.17 GeV with the CLEO-c detector at CESR. We obtain absolute branching fractions for Ds+ decays to KS0 K+, K- K+ pi+, K- K+ pi+ pi-, pi+ pi+ pi-, pi+ eta, and pi+ etaprime. We discuss the problems inherent in measuring accurately the branching fraction for Ds+ to phi pi+, which is often used as a reference mode for measurement of other Ds+ branching fractions, and provide a measurement of a branching fraction that may be useful for this purpose.
Knowledge of the Bs decay fraction of the Y(5S) resonance, fs, is important for Bs meson studies at the Y(5S) energy. Using data collected by the CLEO III detector at CESR consisting of 0.423 1/fb on the Y(5S) resonance, 6.34 1/fb on the Y(4S) and 2.32 1/fb in the continuum below the Y(4S), we measure B(Y(5S)-> phi X)=(13.2+/- 0.7 ^{+2.2}_{-1.4})% and B(Y (4S)-> phi X)=(7.1 +/- 0.1 +/- 0.6)%, the ratio of the two rates is (1.9 +/- 0.1 ^{+0.3}_{-0.2}). This is the first measurement of the phi meson yield from the Y(5S). Using these rates, and a model dependent estimate of B(Bs -> phi X), we measure fs=(27.3 +/- 3.2 ^{+14.6}_{-~6.1})%. We update our previous, independent measurement of this branching fraction using the inclusive Ds yields to be (21.8 +/- 3.4 ^{+8.5}_{-4.2})%, due to changes in the $D_s^+ -> phi π^+$ branching fraction and a better estimate of the number of hadronic events. We also report the total Y(5S) hadronic cross section above continuum to be sigma(e^+e^- -> Y(5S))=(0.301 +/- 0.002 +/- 0.039) nb. This allows us to extract the fraction of B mesons as (58.9+/-10.0+/-9.2)%, equal to 1-fs. Averaging the three methods gives a model dependent result of fs=(26^{+7}_{-4})%.
Using a sample of 3x10^6 psi(2S) decays recorded by the CLEO detector, we study three body decays of the chi_{c0}, chi_{c1}, and chi_{c2} produced in radiative decays of the psi(2S). We consider the decay modes pi+ pi- eta, K+ K- eta, p pbar eta, pi+ pi- etaprime, K+ K- pi0, p pbar pi0, pi+ K- K0S, and K+ pbar Lambda measuring branching fractions or placing upper limits. For chi_{c1} to pi+ pi- eta, K+ K- pi0, and pi+ K- K0S our observed samples are large enough to study the substructure in a Dalitz plot analysis. The results presented in this document are preliminary.
Using data collected with the CLEO III detector at the Cornell Electron Storage Ring, we have compared proton, lambda (charged conjugate modes are implicit) and meson (phi and f2(1270)) production observed in gluon fragmentation vs. quark fragmentation. Two studies have been conducted: in the first, we corroborrate previous per-event particle yields in Upsilon(1S)->ggg vs. e+e- -> qqbar. In the second, we compare particle production in the photon-tagged process U(1S)->gggamma with that in e+e- -> qqbargamma events. For each particle, we determine the `enhancement' ratio, defined as the ratio of particle yields per gluon fragmentation event compared to quark fragmentation event. Thus defined, an enhancement of 1.0 implies equal per-event production in both gluon and quark fragmentation. In the photon-tagged analysis, we find an enhancement of order unity for protons and approximately 1.5 for lambda's. This measured proton enhancement rate is supported by a study of baryon production in chib(J=2)->proton+X relative to chib(J=1)->proton+X. The production of mesons having masses of order 1 GeV (phi and f2(1270)) are found to be also approximately the same in gggamma vs. qqbargamma fragmentation. Overall, per-event baryon production in two-gluon fragmentation is considerably smaller than that observed in three-gluon decays of the Upsilon(1S). Our results for baryon production are inconsistent with the predictions of the JETSET (7.4) fragmentation model.