Observation of the ^1P_1 State of Charmonium

The semileptonic decays of meson $B_c$ to a P-wave charmonium state $\chi_c(^3P_J)$ or $h_c(^1P_1)$ are computed. The results show that the decays are sizable so they are accessible in Tevatron and in LHC, especially, with the detectors LHCB and BTeV in the foreseeable future, and of them, the one to the $^1P_1$ charmonium state potentially offers us a novel window to see the unconfirmed $h_c$ particle. In addition, it is pointed out that since the two charmonium radiative de...

In this talk, recent measurements of charmonium decays of BESIII are presented. Using 448 million $\psi(3686)$ events collected with the BESIII detector, the branching fractions of the decays $\chi_{cJ} \to \phi \phi (J=0,1,2)$ have been measured most precisely, and the polarization parameters of $\chi_{cJ} \to \phi \phi$ have been determined for the first time via a helicity amplitude analysis. Using the same data sample as in the previous study, first evidence of $\eta_c(2S...

The study of the charmonium (cbar c) system is a powerful tool to understand the strong interaction. In pbar p annihilations studied with PANDA, the mass and width of the charmonium state, such as h_c, will be measured with an excellent accuracy, determined by the very precise knowledge of the momentum, p, beam resolution (dp/p=10e(-4)-10e(-5)) and not limited by the resolution of the detector. The analysis of h_c demonstrates the feasibility to accurately determine a specifi...

This paper is aimed at giving a complete review of the latest (post-1998 Physics in Collision conference) experimental results on charm physics.

Measurements of branching fractions for nine different final states, based on a data sample of approximately 4 million psi(2S) events collected with the BESI detector at the BEPC, are reported. Using the same event sample, radiative decays of the psi (2S) into pi pi, K K-bar and eta eta final states have been measured. Cross sections for e e -> e e, hadrons, pi pi J/psi, and mu mu have been measured in the vicinity of the psi(2S) resonance using the BESII detector. The psi(...

Using a sample of 9.7 million B meson pairs collected with the CLEO detector, we study inclusive B meson decays to the chi_c1 and chi_c2 charmonia states. We measure the branching fraction for the inclusive chi_c1 production in B decays to be Br(B->chi_c1 X)=(4.14+-0.31+-0.40)*10^-3, where the first uncertainty is statistical and the second one is systematic. We obtain the branching fractions for direct chi_c1 and chi_c2 production in B decays by subtracting the contribution ...

In the two years since HQL02, the long sought $j_{\ell}=1/2$ states have been observed. In the charmed non-strange sector, these states have the expected properties but, in the charmed strange sector, the states have masses below threshold for the otherwise dominant decay modes, allowing their observation in suppressed modes. Improved measurements of the masses and widths of the well established P-wave charm states have also been published.

New measurements of the masses and decay branching fractions of charmonium and bottomonium states using the data collected by the CLEO detector are presented. These include CLEO identification of the singlet states eta_c'(2S), hc(1P), and eta_b(1S). Comparison with other experimental measurements and theoretical models is also presented.

We report the recent evidence for a new narrow structure, Y(4140), decaying to the $J/\psi \phi$ final state, in exclusive $B^+\to J/\psi\phi K^+$ decays in a data sample corresponding to an integrated luminosity of 2.7 \ifb collected at the CDF II detector. This narrow structure with its mass well above open charm pairs is unlikely to be a candidate for a conventional charmonium state. From a study of the X(3872) mass and width based on the world's largest sample of $X(3872)...

Using 58 million $J/\psi$ decays, we have investigated the $p \bar{p}$ invariant mass spectrum in the radiative decay $J/\psi \to \gamma p \bar{p}$ and observe a prominent structure with mass near $2m_p$. Fitting with an S-wave Breit-Wigner, we obtain a peak mass of $M= 1859^{+3}_{-10}(\rm stat)^{+5}_{-25}(sys) MeV/c^2$. $J/\psi \to \gamma \eta_c$ decays from the same sample are used to determine the mass, width, and hadronic branching ratios of the $\eta_c$. From a sample of...