Evidence for a J/psi-ppbar Pauli Strong Coupling ?

The couplings of charmonia and charmonium hybrids (generically Psi) to ppbar are of great interest in view of future plans to study these states using an antiproton storage ring at GSI. These low to moderate energy Psi-ppbar couplings are not well understood theoretically, and currently must be determined from experiment. In this letter we note that the two independent Dirac (gamma_mu) and Pauli (sigma_munu) ppbar couplings of the J/psi and psi' can be constrained by the angular distribution of e+e- -> (J/psi, psi') -> ppbar on resonance. A comparison of our theoretical results to recent unpolarized data allows estimates of the ppbar couplings; in the better determined J/psi case the data is inconsistent with a pure Dirac (gamma_mu) coupling, and can be explained by the presence of a sigma_munu term. This Pauli coupling may significantly affect the cross section of the PANDA process p pbar -> pi0 J/psi near threshold. There is a phase ambiguity that makes it impossible to uniquely determine the magnitudes and relative phase of the Dirac and Pauli couplings from the unpolarized angular distributions alone; we show in detail how this can be resolved through a study of the polarized reactions.Comment: 7 pages, 7 figures. v2 generalizes v1 to complex J/psi-ppbar coupling

On the Particle Data Group evaluation of Psi' and chi_c Branching Ratios

I propose a new evaluation of $\psi'(2S)$ and $\chi_c(1P)$ branching ratios which avoids the correlations affecting the current Particle Data Group evaluation. These correlations explain the apparent technique-dependent discrepancies between the available determinations of the ${\cal B}(\chi_c(1P)\to p\bar p)$ and $\Gamma(\chi_c(1P)\to \gamma\gamma)$ under the hypotesis that the current values of the $\psi'(2S)\to\chi_c(1P)\gamma$ branching ratios are overestimated. In the process I also noticed that Particle Data Group has not restated many of the older measurements, when necessary, for the new value of ${\cal B}(J/\psi\to l^+l^-)$, which significantly affects the evaluation of some relevant $\psi'(2S)$ and $\chi_c(1P)$ exclusive branching ratios.Comment: 13 pages. Revised version. Submitted to Phys. Rev.

E835 at FNAL: Charmonium Spectroscopy in pˉp\bar p p Annihilations

I present preliminary results on the search for $h_c$ in its $\eta_c\gamma$ and $J/\psi\pi^0$ decay modes. We observe an excess of \eta_c\gamma$events near 3526 MeV that has a probability${\cal P} \sim 0.001$to arise from background fluctations. The resonance parameters are$M=3525.8 \pm 0.2 \pm 0.2 $MeV,$\Gamma\leq$1 MeV, and$10.6\pm 3.7\pm3.4(br) < \Gamma_{\bar{p}p}B_{\eta_c\gamma} < 12.8\pm 4.8\pm4.5(br) $eV. We find no event excess within the search region in the$J/\psi\pi^0$ mode.Comment: Presented at the 6th International Conference on Hyperons, Charm and Beauty Hadrons (BEACH 2004), Chicago(Il), June 27-July 3,200

Charmless Three-Body Baryonic B Decays

Motivated by recent data on B-> p pbar K decay, we study various charmless three-body baryonic B decay modes, including Lambda pbar pi, Sigma0 pbar pi, p pbar pi, p pbar Kbar0, in a factorization approach. These modes have rates of order 10^{-6}. There are two mechanisms for the baryon pair production, current-produced and transition. The behavior of decay spectra from these baryon production mechanisms can be understood by using QCD counting rules. Predictions on rates and decay spectra can be checked in the near future.Comment: 26 pages, 9 figures; version to appear in Phys. Rev.

Closed-flavor pi + J/psi and pi + Upsilon Cross Sections at Low Energies from Dipion Decays

The scale of low energy c-cbar and b-bbar cross sections on light hadrons is of great importance to searches for the quark gluon plasma using the heavy-quarkonium suppression signature. Unfortunately, little is known about these near-threshold cross sections at present, and recent theoretical estimates span many orders of magnitude. Here we use experimental data on the four observed closed-flavor heavy quarkonium hadronic decays psi' -> pi pi J/psi, Upsilon' -> pi pi Upsilon, Upsilon'' -> pi pi Upsilon and Upsilon'' -> pi pi Upsilon', combined with simple models of the transition amplitudes, to estimate the pion scattering cross sections of c-cbar and b-bbar mesons near threshold. Specifically we consider the closed-flavor reactions pi J/psi -> pi psi', pi Upsilon -> pi Upsilon', pi Upsilon -> pi Upsilon'' and pi Upsilon' -> pi Upsilon'' and their time-reversed analogues. Our results may be useful in constraining theoretical models of the strong interactions of heavy quarkonia, and can be systematically improved through future detailed studies of dipion decays, notably psi' -> pi pi J/psi and Upsilon'' -> pi pi Upsilon.Comment: 6 pages, 6 figure

Recalculation of Proton Compton Scattering in Perturbative QCD

At very high energy and wide angles, Compton scattering on the proton (gamma p -> gamma p) is described by perturbative QCD. The perturbative QCD calculation has been performed several times previously, at leading twist and at leading order in alpha_s, with mutually inconsistent results, even when the same light-cone distribution amplitudes have been employed. We have recalculated the helicity amplitudes for this process, using contour deformations to evaluate the singular integrals over the light-cone momentum fractions. We do not obtain complete agreement with any previous result. Our results are closest to those of the most recent previous computation, differing significantly for just one of the three independent helicity amplitudes, and only for backward scattering angles. We present results for the unpolarized cross section, and for three different polarization asymmetries. We compare the perturbative QCD predictions for these observables with those of the handbag and diquark models. In order to reduce uncertainties associated with alpha_s and the three-quark wave function normalization, we have normalized the Compton cross section using the proton elastic form factor. The theoretical predictions for this ratio are about an order of magnitude below existing experimental data.Comment: Latex, 23 pages, 13 figures. Checked numerical integration one more way; added results for one more proton distribution amplitude; a few other minor changes. Version to appear in Phys. Rev.

Tracking Performance of the Scintillating Fiber Detector in the K2K Experiment

The K2K long-baseline neutrino oscillation experiment uses a Scintillating Fiber Detector (SciFi) to reconstruct charged particles produced in neutrino interactions in the near detector. We describe the track reconstruction algorithm and the performance of the SciFi after three years of operation.Comment: 24pages,18 figures, and 1 table. Preprint submitted to NI

Branching Fraction Measurements of psi(2S) Decay to Baryon-Antibaryon Final States

Using 3.08 million psi(2S) decays observed in e^+e^- collisions by the CLEO detector, we present the results of a study of the psi(2S) decaying into baryon-antibaryon final states. We report the most precise measurements of the following eight modes: proton-antiproton, lambda-antilambda, Xi^- antiXi^-, Xi^0-antiXi^0 (first observation), Sigma+-antiSigma^+ (first observation), and Sigma^0-antiSigma^0, and place upper limits for the modes, Xi^0*-antiXi^0* and Omega^- antiOmega^-.Comment: 8 pages postscript,also available through http://www.lns.cornell.edu/public/CLNS/2005/, submitted to PR

Measurement of the Resonance Parameters of the χ1(13P1)\chi_{1}(1^3P_1) and χ2(13P2)\chi_{2}(1^3P_2) States of Charmonium formed in Antiproton-Proton Annihilations

We have studied the $^3P_J$ ($\chi_c)$ states of charmonium in formation by antiproton-proton annihilations in experiment E835 at the Fermilab Antiproton Source. We report new measurements of the mass, width, and $B(\chi_{cJ} \to \bar{p} p) \times \Gamma(\chi_{cJ} \to J/\psi + anything)$ for the $\chi_{c1}$ and $\chi_{c2}$ by means of the inclusive reaction $\bar{p}p \to \chi_{cJ} \to J/\psi + anything \to (e^{+}e^{-}) +anything$. Using the subsample of events where $\chi_{cJ} \to \gamma + J/\psi \to \gamma + (e^{+}e^{-})$ is fully reconstructed, we derive $B(\chi_{cJ} \to \bar p p)\times \Gamma(\chi_{cJ} \to J/\psi + \gamma)$. We summarize the results of the E760 (updated) and E835 measurements of mass, width and $B(\chi_{cJ} \to \bar{p}p) \Gamma(\chi_{cJ} \to J/\psi+\gamma)$ (J=0,1,2) and discuss the significance of these measurements

Measurements of psi(2S) decays to octet baryon-antibaryon pairs

With a sample of 14 million psi(2S) events collected by the BESII detector at the Beijing Electron Positron Collider (BEPC), the decay channels psi(2S)->p p-bar, Lambda Lambda-bar, Sigma0 Sigma0-bar, Xi Xi-bar are measured, and their branching ratios are determined to be (3.36+-0.09+-0.24)*10E-4, (3.39+-0.20+-0.32)*10E-4, (2.35+-0.36+-0.32)*10E-4, (3.03+-0.40+-0.32)*10E-4, respectively. In the decay psi(2S)->p p-bar, the angular distribution parameter alpha is determined to be 0.82+-0.17+-0.04.Comment: 8 pages, 8 figure