Heavy Quarkonium

I review heavy quarkonium physics in view of recent experimental results. In particular, I discuss new results on spin singlet states, photon and hadronic transitions, D-states and discovery of yet unexplained narrow X(3872) state.Comment: 15 pages, 16 figures. 2nd version: minor changes in references and text. Invited talk presented at the 21st International Symposium On Lepton And Photon Interactions At High Energies (LP03) 11-16 August 2003, Batavia, Illinoi

Measurements of Branching Fractions for Electromagnetic Transitions Involving the χ_{bJ}(1P) States

Using 9.32, 5.88 million Upsilon(2S,3S) decays taken with the CLEO-III detector, we obtain five product branching fractions for the exclusive processes Upsilon(2S) =\u3e gamma chi_{b0,1,2}(1P) =\u3e gamma gamma Upsilon(1S) and Upsilon(3S) =\u3e gamma chi_{b1,2}(1P) =\u3e gamma gamma Upsilon(1S). We observe the transition chi_{b0}(1P) =\u3e gamma Upsilon(1S) for the first time. Using the known branching fractions for B[Upsilon(2S) =\u3e gamma chi_{bJ}(1P)], we extract values for B[chi_{bJ}(1P) =\u3e gamma Upsilon(1S)] for J=0, 1, 2. In turn, these values can be used to unfold the Upsilon(3S) product branching fractions to obtain values for B[Upsilon(3S) =\u3e gamma chi_{b1,2}(1P) for the first time individually. Comparison of these with each other and with the branching fraction B[Upsilon(3S) =\u3e gamma chi_{b0}] previously measured by CLEO provides tests of relativistic corrections to electric dipole matrix elements

Analysis of the Decay D0 → K0Sπ0π0

We present the results of a Dalitz plot analysis of D^0 to K^0_S pi^0 pi^0 using the CLEO-c data set of 818 inverse pico-barns of e^+ e^- collisions accumulated at sqrt{s} = 3.77 GeV. This corresponds to three million D^0 D^0-bar pairs from which we select 1,259 tagged candidates with a background of 7.5 +- 0.9 percent. Several models have been explored, all of which include the K^*(892), K^*_2(1430), K^*(1680), the f_0(980), and the sigma(500). We find that the combined pi^0 pi^0 S-wave contribution to our preferred fit is (28.9 +- 6.3 +- 3.1)% of the total decay rate while D^0 to K^*(892)^0 pi^0 contributes (65.6 +- 5.3 +- 2.5)%. Using three tag modes and correcting for quantum correlations we measure the D^0 to K^0_S pi^0 pi^0 branching fraction to be (1.059 +- 0.038 +- 0.061)%

Observation of the Dalitz Decay Ds*+ → Ds*+ e+e-

Using 586 \textrm{pb}^{-1} of e^{+}e^{-} collision data acquired at \sqrt{s}=4.170 GeV with the CLEO-c detector at the Cornell Electron Storage Ring, we report the first observation of D_{s}^{*+} \to D_{s}^{+} e^{+} e^{-} with a significance of 5.3 \sigma. The ratio of branching fractions \calB(D_{s}^{*+} \to D_{s}^{+} e^{+} e^{-}) / \calB(D_{s}^{*+} \to D_{s}^{+} \gamma) is measured to be [ 0.72^{+0.15}_{-0.13} (\textrm{stat}) \pm 0.10 (\textrm{syst})]%, which is consistent with theoretical expectations

Study of Ψ(2S) Decays to γpp, π0pp and η pp and Search for pp Threshold Enhancements

The decays of psi(2S) into gamma p bar{p}, pi^0 p bar{p} and eta p bar{p} have been studied with the CLEO-c detector using a sample of 24.5 million psi(2S) events obtained from e^+e^- annihilations at sqrt{s} = 3686 MeV. The data show evidence for the excitation of several N^* resonances in p pi^0 and p eta channels in pi^0 p bar{p} and eta p bar{p} decays, and f_2 states in gamma p bar{p} decay. Branching fractions for decays of psi(2S) to gamma p bar{p}, pi^0 p bar{p} and eta p bar{p} have been determined. No evidence for p bar{p} threshold enhancements was found in the reactions psi(2S)-\u3e X p bar{p}, where X = gamma, pi^0, eta. We do, however, find confirming evidence for a p bar{p} threshold enhancement in J/psi-\u3e gamma p bar{p} as previously reported by BES

Observation of the Hc(1P) Using e+e- Collisions Above DD Threshold

Using 586pb^-1 of e^+e^- collision data at E_CM = 4170MeV, produced at the CESR collider and collected with the CLEO-c detector, we observe the process e^+e^- --\u3e pi^+ pi^- h_c(1P). We measure its cross section to be 15.6+-2.3+-1.9+-3.0pb, where the third error is due to the external uncertainty on the branching fraction of psi(2S) --\u3e pi^0 h_c(1P), which we use for normalization. We also find evidence for e^+e^- --\u3e eta h_c(1P) at 4170MeV at the 3sigma level, and see hints of a rise in the e^+e^- --\u3e pi^+ pi^- h_c(1P) cross section at 4260MeV

Search for the Decay D^+_{s}\toωe^+ν

We present the first search for the decay D^+_{s}\to \omega e^{+}\nu to test the four-quark content of the D^+_{s} and the \omega-\phi mixing model for this decay. We use 586 \mathrm{pb}^{-1} of e^{+}e^{-} collision data collected at a center-of-mass energy of 4170 MeV. We find no evidence of a signal, and set an upper limit on the branching fraction of \mathcal{B}(D^+_{s}\to\omega e^+\nu

Upsilon(1S)-\u3eGamma+f2\u27(1525); f2\u27(1525)-\u3eK0sK0s Decays

We report on a study of exclusive radiative decays of the Upsilon(1S) resonance into a final state consisting of a photon and two K0s candidates. We find evidence for a signal for Upsilon(1S)-\u3egamma f_2\u27(1525); f_2\u27(1525)-\u3eK0sK0s, at a rate (4.0+/-1.3+/-0.6)x10^{-5}, consistent with previous observations of Upsilon(1S)-\u3egamma f_2\u27(1525); f_2\u27(1525)-\u3eK+K-, and isospin. Combining this branching fraction with existing branching fraction measurements of Upsilon(1S)-\u3egamma f_2\u27(1525) and J/psi-\u3egamma f_2\u27(1525), we obtain the ratio of branching fractions: B(Upsilon(1S)-\u3egamma f_2\u27(1525))/B(J/psi-\u3egamma f_2\u27(1525))=0.09+/-0.02, approximately consistent with expectations based on soft collinear effective theory

Studies of D^+ -\u3e {eta\u27, eta, phi} e^+ nu_e

We report the first observation of the decay D^+ -\u3e eta\u27 e^+ nu_e in two analyses, which combined provide a branching fraction of B(D+ -\u3e eta\u27 e nu) = (2.16 +/- 0.53 +/- 0.07) x 10^{-4}. We also provide an improved measurement of B(D+ -\u3e eta e nu) = (11.4 +/- 0.9 +/- 0.4) x 10^{-4}, provide the first form factor measurement, and set the improved upper limit B(D+ -\u3e phi e nu) \u3c 0.9 x 10^{-4} (90% C.L.)

Branching Fractions for Y(3S) -\u3e pi^0 h_b and psi(2S) -\u3e pi^0 h_c

Using e^+e^- collision data corresponding to 5.88M Y(3S) [25.9M psi(2S)] decays and acquired by the CLEO III [CLEO-c] detectors operating at CESR, we study the single-pion transitions from Y(3S) [psi(2S)] to the respective spin-singlet states h_{b[c]}. Utilizing only the momentum of suitably selected transition-pi^0 candidates, we obtain the upper limit B(Y(3S) -\u3e pi^0 h_b) \u3c 1.2\times 10^{-3} at 90% confidence level, and measure B(psi(2S) -\u3e pi^0 h_c) = (9.0+-1.5+-1.3)\times 10^{-4}. Signal sensitivities are enhanced by excluding very asymmetric pi^0 -\u3e gamma gamma candidates