Two-photon width of the charmonium state X_(c2)

The two-photon width of X_(c2)^3P_2 state of charmonium has been measured using 14.4 fb^(-1) of e^+e^-data taken at √s =9.46–11.30 GeV with the CLEO III detector. The yy-fusion reaction studied is e^+e^- → e^+e^-yy, → yy X_(c2) → yJ/Ψ → ye^+e^-(µ^+µ^-). We measure Г_(yy) (X_(c2))B(X_(c2)) → y J/Ψ)B(J/Ψ → e^+e^- + µ^+µ^-)= 13.2 ± 1.4(stat)± 1.1(syst) eV, and obtain Г yy(Xc2)= 559 ± 57(stat) ± 48(syst) ± 36(br) eV. This result is in excellent agreement with the result of -fusion measurement by Belle and is consistent with that of the pp → X_(c2) → yy measurement, when they are both reevaluated using the recent CLEO result for the radiative decay X_(c2) → J/Ψ

A Comprehensive Study of the Radiative Decays of J/ψJ/\psi and ψ(2S)\psi(2S) to Pseudoscalar Meson Pairs, and Search for Glueballs

Using 53 pb$^{-1}$ of $e^+e^-$ annihilation data taken at $\sqrt{s}=3.686$ GeV, a comprehensive study has been made of the radiative decays of samples of 5.1 million $J/\psi$ and 24.5 million $\psi(2S)$ into pairs of pseudoscalar mesons, $\pi^+\pi^-$, $\pi^0\pi^0$, $K^+K^-$, $K_S^0K_S^0$, and $\eta\eta$. Product branching fractions for the radiative decays of $J/\psi$ and $\psi(2S)$ to scalar resonances $f_0(1370,1500,1710,2100, \text{and} 2200)$, and tensor resonances $f_2(1270,1525, \text{and} 2230)$ have been determined, and are discussed in relation to predicted glueballs. For $\psi(2S)$ radiative decays the search for glueballs has been extended to masses between 2.5 GeV and 3.3 GeV.Comment: 21 pages, 14 figures, published in PR

Simulating the impact of the Smith Cloud

We investigate the future evolution of the Smith Cloud by performing hydrodynamical simulations of the cloud impact onto the gaseous Milky Way Galactic disk. We assume a local origin for the cloud and thus do not include a dark matter component to stabilize it. Our main focus is the cloud's influence on the local and global star formation rate (SFR) of the Galaxy and whether or not it leads to an observable event in the far future. Our model assumes two extremes for the mass of the Smith Cloud, an upper mass limit of 10$^7$ M$_{\odot}$ and a lower mass limit of 10$^6$ M$_{\odot}$, compared to the observational value of a few 10$^6$ M$_{\odot}$. In addition, we also make the conservative assumption that the entirety of the cloud mass of the extended Smith Cloud is concentrated within the tip of the cloud. We find that the impact of the low-mass cloud produces no noticeable change in neither the global SFR nor the local SFR at the cloud impact site within the galactic disk. For the high-mass cloud we find a short-term (roughly 5 Myr) increase of the global SFR of up to 1 M$_{\odot}$ yr$^{-1}$, which nearly doubles the normal Milky Way SFR. This highly localized starburst should be observable.Comment: 14 pages, 5 figure

First Measurement of the Electromagnetic Form Factor of the Neutral Kaon at a Large Momentum Transfer and the Effect of SU(3)SU(3) Breaking

At large momentum transfers the photon interacts with the charges and spins of the constituent partons in a hadron. It is expected that the neutral kaon can acquire finite electromagnetic form factors because its wave function is affected by the order of magnitude difference between the mass of the strange quark and that of the down quark, or flavor $SU(3)$ breaking. We report on the first measurement of the form factor of neutral kaons at the large timelike momentum transfer of $|Q^2|=17.4$ GeV$^2$ by measuring the cross section for $e^+e^-\to K_SK_L$ at $\sqrt{s}=4.17$ GeV using CLEO-c data with an integrated luminosity of 586 pb$^{-1}$. We obtain $F_{K_SK_L}(17.4~\textrm{GeV}^2)=5.3\times10^{-3}$, with a 90% C.L. interval of $(2.9-8.2)\times10^{-3}$. This is nearly an order of magnitude smaller than $F_{K^+K^-}(17.4~\textrm{GeV}^2)=(44\pm1)\times10^{-3}$, and indicates that the effect of $SU(3)$ breaking is small. In turn, this makes it unlikely that the recently observed strong violation of the pQCD prediction, $F_{\pi^+\pi^-}(|Q^2|)/F_{K^+K^-}(|Q^2|)=f_\pi^2/f_K^2$, which is based on the assumption of similar wave functions for the pions and kaons, can be attributed to $SU(3)$ breaking alone.Comment: 4 pages, 2 figures, accepted to PL