Ja n 20 02 Short - range correlations and meson exchange currents in photonucleon emission
نویسندگان
چکیده
One-nucleon emission processes induced by photon absorption are studied by considering short-range correlations effects. At energies above the giant resonance region the validity of the direct knockout model has been tested by comparison with continuum Random Phase Approximation results. Nucleon re-scattering effects have been considered by using an optical potential. The role of the electromagnetic convection, magnetization and meson exchange currents has been investigated as a function of both excitation energy and momentum transfer. The short-range correlation effects have been studied by using various correlation functions. We found that the nucleon photo-emission cross section is rather sensitive to the presence of short-range correlations at large values of nucleon emission angle. In this region, however, the effects of meson exchange currents are even larger than those produced by short-range correlations.
منابع مشابه
Proton emission induced by polarized photons
The proton emission induced by polarized photons is studied in the energy range above the giant resonance region and below the pion emission threshold. Results for the C, O and Ca nuclei are presented. The sensitivity of various observables to final state interaction, meson exchange currents and short range correlations is analyzed. We found relevant effects due to the virtual excitation of the...
متن کاملth / 0 10 50 58 v 2 2 8 Ja n 20 02 Charmonium - Pion Cross Section from QCD Sum Rules
The J/ψ π → ¯ D D cross sections as a function of √ s are evaluated in a QCD sum rule calculation. We study the Borel sum rule for the four point function involving pseudoscalar and vector meson currents, up to dimension four in the operator product expansion. We find that our results are smaller than the J/ψ π → charmed mesons cross sections obtained with models based on meson exchange, but ar...
متن کاملPionic correlations and meson-exchange currents in two- particle emission induced by electron scattering
Citation Amaro, J. et al. " Pionic correlations and meson-exchange currents in two-particle emission induced by electron scattering. " Physical Review C 82.4 (2010): n. pag. Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The MIT Faculty has made this article openly available. Plea...
متن کاملar X iv : h ep - p h / 03 02 13 2 v 3 2 2 Ja n 20 07 2 - loop QCD corrections to B c - meson leptonic constant .
We present results for two-loop QCD corrections to the short distance coefficient that governs leptonic decay of Bc-meson. After brief discussion of the technics of asymptotic expansion used to perform this calculation, we give comments on the numerical value of two-loop corrections and its impact on NRQCD description of Bc-meson bound state. PACS: 12.39.Jh, 13.25.Gv, 14.40.Lb, 14.40.Nd
متن کاملar X iv : h ep - p h / 02 12 31 4 v 1 2 0 D ec 2 00 2 IMPORTANT CONFIGURATIONS FOR NN PROCESSES IN A GOLDSTONE BOSON EXCHANGE MODEL
We study the short-range nucleon-nucleon interaction in a nonrelativistic chiral constituent quark model by diagonalizing a Hamiltonian containing a linear confinement and a Goldstone boson exchange interaction between quarks. A finite six-quark basis obtained from single particle cluster model states was previously used. Here we show that the configurations which appear naturally through the u...
متن کامل