Probing Proton Strangeness with Time-Like Virtual Compton Scattering

We document that p(gamma,e+e-)p measurements will yield new, important information about the off-shell time-like nucleon form factors, especially in the phi meson region (q^2 = M^2_{phi}) governing the phi N couplings g^{V,T}_{\phi N N}. Calculations for p(gamma,e+e-)p, utilizing vector meson dominance, predict measurable phi enhancements at high |t| compared to the expected phi background production from pi, eta and Pomeron exchange. The phi form factor contribution generates a novel experimental signature for OZI violation and the proton strangeness content. The phi N couplings are determined independently from a combined analysis of the neutron electric form factor and recent high |t| phi photoproduction. The pi, eta and Pomeron transition form factors are also predicted and the observed pi and eta transition moments are reproduced.Comment: 9 pages, 6 figure

Elektromagnetska tvorba hiperona i gluonske lopte

An analysis of new kaon electroproduction measurements at Jefferson Lab is presented for both proton and deuteron targets. Calculations based upon quantum hadrodynamics are compared to the experimental longitudinal and transverse separated cross sections for elementary KΛ production. Also confronted by data are model predictions for d(e,e’K+)YN inclusive measurements with YN = Λn, Σ0n and Σ−p. In general, both proton and deuteron target experiments are reasonably well described. Finally, glueball production, possible with the anticipated Jefferson Lab beam energy upgrade, is discussed in conjunction with results from a QCD Hamiltonian calculation for the low-lying gluonia spectrum.Opisuje se analiza novih mjerenja elektrotvorbe kaona na protonskim i deuteronskim metama u Jefferson Lab. Uspoređuju se ishodi računa zasnovani na kvantnoj hadrodinamici s razdvojenim eksperimentalnim uzdužnim i poprečnim udarnim presjecima za elementarnu tvorbu KΛ. Nalazi se također nesuglasje mjerenih podataka s predviđanjima modela za inkluzivna mjerenja d(e,e’K+)YN s YN = Λn, Σ 0n i Σ−p. Opća je ocjena da se mjerenja s protonskom i s deuteronskom metom dobro opisuju. Raspravlja se također tvorba gluonskih lopti, koja će biti moguća s predviđenom povećanom energijom snopa u Jefferson Lab, u svezi s ishodima računa s QCD Hamiltonovom funkcijom za niskoenergijski spektar gluonija

Coulombov baždarni Hamiltonijan: napredak i primjene

Theoretical developments and applications of an effective QCD Hamiltonian in the Coulomb gauge are summarized. BCS, TDA and RPA many-body diagonalizations in the quark and gluon sectors are reported for meson and glueball spectra, respectively. The model glueball Regge trajectories are in good agreement with the established pomeron and a recently observed odd signature daughter. Using the pomeron-glueball connection and vector meson dominance, glueball photoproduction cross sections and decays are calculated and a glueball experimental signature is predicted. The pseudoscalar-vector meson mass splittings are also investigated using a hyperfine interaction based upon transverse gluon exchange. An improved meson spectrum is obtained and the dominant role of chiral symmetry in the π-ρ mass difference is confirmed.Daje se pregled teorijskog razvoja i primjena efektivnog Hamiltonijana QCD u Coulombskoj baždarnosti. Navode se višečestične BCS, TDA i RPA dijagonalizacije u kvarkovskom i gluonskom sektoru za spektre mezona i gluonskih lopti. Reggeove putanje modelskih gluonskih lopti su u dobrom skladu s potvrđenim pomeronom i nedavno opaženom kćeri s neparnim znakom. Primjenom veze pomeron – gluonska lopta i prevladavanja vektorskih mezona, izračunali smo udarne presjeke za fototvorbu gluonskih lopti i njihovih raspada, i predviđaju se značajke za eksperimentalno nalaženje. Također se istražuju cijepanja masa pseudoskalarno-vektorskih mezona zasnovana na poprečnoj izmjeni gluona. Postigli smo poboljšan spektar mezona i potvrdili prevladavajuću ulogu kiralne simetrije glede razlike masa π i ρ

Relativistic Many-Body Hamiltonian Approach to Mesons

We represent QCD at the hadronic scale by means of an effective Hamiltonian, $H$, formulated in the Coulomb gauge. As in the Nambu-Jona-Lasinio model, chiral symmetry is explicity broken, however our approach is renormalizable and also includes confinement through a linear potential with slope specified by lattice gauge theory. This interaction generates an infrared integrable singularity and we detail the computationally intensive procedure necessary for numerical solution. We focus upon applications for the $u, d, s$ and $c$ quark flavors and compute the mass spectrum for the pseudoscalar, scalar and vector mesons. We also perform a comparative study of alternative many-body techniques for approximately diagonalizing $H$: BCS for the vacuum ground state; TDA and RPA for the excited hadron states. The Dirac structure of the field theoretical Hamiltonian naturally generates spin-dependent interactions, including tensor, spin-orbit and hyperfine, and we clarify the degree of level splitting due to both spin and chiral symmetry effects. Significantly, we find that roughly two-thirds of the $\pi$-$\rho$ mass difference is due to chiral symmetry and that only the RPA preserves chiral symmetry. We also document how hadronic mass scales are generated by chiral symmetry breaking in the model vacuum. In addition to the vacuum condensates, we compute meson decay constants and detail the Nambu-Goldstone realization of chiral symmetry by numerically verifying the Gell-Mann-Oaks-Renner relation. Finally, by including D waves in our charmonium calculation we have resolved the anomalous overpopulation of $J/\Psi$ states relative to observation