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

Search for Missing Charmonium States in B-meson Decays

The recent progress in experiments at B-factories suggests an opportunity to search for missing charmonium states $\eta_{c}'(2^1S_0)$ and $h_c(1^1P_1)$. The feasibility of such a search in B-meson decays are discussed.Comment: LaTex, 9 pages, no figures. To appear in Phys. Lett.

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.

The Lost Tribes of Charmonium

To illustrate the campaign to extend our knowledge of the charmonium spectrum, I focus on a puzzling new state, $X(3872) \to \pi^+\pi^- J/\psi$. Studying the influence of open-charm channels on charmonium properties leads us to propose a new charmonium spectroscopy: additional discrete charmonium levels that can be discovered as narrow resonances of charmed and anticharmed mesons. I call attention to open issues for theory and experiment.Comment: 11 pages, 11 figures, uses espcrc2.sty (included); presented at BEACH 2004, 28 June - 3 July, IIT/Chicag

Prediction of Three-body B0→ρ−pnˉ,π−pnˉB^0\to \rho^-p\bar{n}, \pi^-p\bar{n} Decay Rates

We predict the rates of the charmless three-body $B^0\to \rho^-p\bar{n}$ and $\pi^-p\bar{n}$ modes due to weak vector current contributions to be $\sim 4\times 10^{-6}$ and $2\times 10^{-6}$, respectively. The basis is a factorization approach of current produced nucleon pairs, together with an isospin transformation that relates nucleon weak vector form factors to electromagnetic form factors. Adding the axial vector current contribution, we find $B^0\to \rho^-p\bar{n}$ and $B^+\to \rho^0p\bar{n}$ to be at $10^{-5}$ order. The three-body modes appear to dominate over the two-body modes such as $B\to p\bar{p}$, $p\bar \Lambda$.Comment: 5 pages, 4 figures. Version to appear in Phys. Lett.

Nucleon Form Factors in Dispersion Theory

Dispersion relations provide a powerful tool to analyse the electromagnetic form factors of the nucleon both in the space-like and time-like regions with constraints from other experiments, unitarity, and perturbative QCD. We give a brief introduction into dispersion theory for nucleon form factors and present first results from our ongoing form factor analysis. We also calculate the two-pion continuum contribution to the isovector spectral functions drawing upon the new high statistics measurements of the pion form factor by the CMD-2, KLOE, and SND collaborations.Comment: 9 pages, 9 figures, invited talk at the Symposium "20 Years of Physics at the Mainz Microtron MAMI", October 20-22, 2005, Mainz, German

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.

A model for space and time-like proton (neutron) form factors

A model is suggested to describe the known experimental behavior of nucleon form factors both in space and time-like regions. It implies quarks to be colorless in the region of high intensity chomo-magnetic gluon field inside the nucleon.Comment: 6 pages, 3 figure

Nucleon electromagnetic form factors and polarization observables in space-like and time-like regions

We perform a global analysis of the experimental data of the electromagnetic nucleon form factors, in space-like and time-like regions. We give the expressions of the observables in annihilation processes, such as $p+\bar{p}\to \ell^+ +\ell^-$, $\ell=e$ or $\mu$, in terms of form factors. We discuss some of the phenomenological models proposed in the literature for the space-like region, and consider their analytical continuation to the time-like region. After determining the parameters through a fit on the available data, we give predictions for the observables which will be experimentally accessible with large statistics, polarized annihilation reactions.Comment: 25 pages, 5 figures 7 table

Final State Interaction Effects in the e+e−→NNˉe^+e^-\to N\bar{N} Process near Threshold

We use the Paris nucleon-antinucleon optical potential for explanation of experimental data in the process $e^+e^- \to p\bar p$ near threshold. It is shown that the cross section and the electromagnetic form factors are very sensitive to the parameters of the potential. It turns out that final-state interaction due to slightly modified absorptive part of the potential allows us to reproduce available experimental data. We also demonstrated that the cross section in $n\bar{n}$ channel is larger than that in $p\bar{p}$ one, and their ratio is almost energy independent up to 2.2 GeV.Comment: references added, changes in the text according to referee comment