Pionic Degrees of Freedom in Atomic Nuclei and Quasielastic Knockout of Pions by High-Energy Electrons

The nonlinear model of pionic condensate in nuclei by G. Preparata can be efficiently verified by investigation of the quasielastic knockout process of pions out of nuclei by high energy electrons. First, a momentum distribution (MD) of the collective pions has a bright maximum at q=0.3 Gev.Second the excitation spectrum of a recoil nucleus is concentrated at low energies E lesser than 1MeV. The results for the pion knockout from mesonic clouds of individual nucleons are absolutely different. The latter results are presented both for pion and rho-meson clouds localized on nucleons.Comment: 13 pages, 3 figure

Bremsstrahlung of 350--450 MeV protons as a tool to study NNNN interaction off-shell

The $pp\to pp\gamma$ bremsstrahlung cross section is calculated within the method of coordinate space representation. It is shown that in the beam energy range of 350--450~MeV a deep attractive NN-potential with forbidden states (Moscow potential) and realistic meson exchange potentials (MEP) give rise to the cross sections that differ essentially in shape: the cross sections nearly coincide in the minima but differ by a factor of 5 approximately in the maxima. Therefore, the $pp\to pp\gamma$ reaction at energies $\sim$350--450~Mev can be used to study $NN$ interaction off-shell and to discriminate experimentally between MEP and Moscow potential.Comment: 5 pages, latex, 4 PS figures. Talk presented by Andrey Shirokov at the International Conference on Quark Lepton Nuclear Physics ``QULEN97'', May 20-23, 1997, Osaka, Japan; to be published in Nucl. Phys.

Quasi-elastic knockout of pions and kaons from nucleons by high-energy electrons and quark microscopy of "soft" meson degrees of freedom in the nucleon

Electro-production of pions and kaons at the kinematics of quasi-elastic knockout (which is well known in the physics of atomic nucleus and corresponds to the $t$-pole diagram) is proposed for obtaining their momentum distribution (MD) in various channels of virtual decay $N \to B+\pi$, $B=N$, $\Delta$, $N^*$, $N^{**}$, and $N \to Y+K$, $Y=\Lambda$, $\Sigma$. It is a powerful tool for investigation of a quark microscopic picture of the meson cloud in the nucleon. A model of scalar $q \bar{q}$ ($^3P_0$) fluctuation in the non-trivial QCD vacuum is used to calculate pion and kaon momentum distributions (MD) in these channels.Comment: 31 pages, 11 figures, submitted to Nucl.Phys.

Nucleon-nucleon wave function with short-range nodes and high-energy deuteron photodisintegration

We review a concept of the Moscow potential (MP) of the $NN$ interaction. On the basis of this concept we derive by quantum inversion optical partial potentials from the modern partial-wave analysis (PWA) data and deuteron properties. Point-form (PF) relativistic quantum mechanics (RQM) is applied to the two-body deuteron photodisintegration. Calculations of the cross-section angular distributions cover photon energies between 1.1 and 2.5 GeV. Good agreement between our theory and recent experimental data confirms the concept of deep attractive Moscow potential with forbidden $S$- and $P$-states.Comment: 31 pages, 9 figures. typos, extended formalism, review of the Moscow potential model adde

Light and strange baryons, two-baryon systems and the chiral symmetry of QCD

Beyond the scale of spontaneous breaking of chiral symmetry light and strange baryons should be considered as systems of three constituent quarks with confining interaction and a chiral interaction that is mediated by Goldstone bosons between the constituent quarks. The flavor-spin structure and sign of the short-range part of the Goldstone boson exchange interaction reduces the $SU(6)_{FS}$ symmetry down to $SU(3)_F \times SU(2)_S$, induces hyperfine splittings and provides correct ordering of the lowest states with positive and negative parity. A unified description of light and strange baryon spectra calculated in a semirelativistic framework is presented. It is demonstrated that the same short-range part of the Goldstone boson exchange between the constituent quarks induces a strong short-range repulsion in $NN$ system when the latter is treated as $6Q$ system. Similar to the $NN$ system there should be a short-range repulsion in other $NY$ and $YY$ two-baryon systems. We also find that the compact 6Q system with the "H-particle" quantum numbers lies a few hundreds MeV above the $\Lambda\Lambda$ threshold. It then suggests that the deeply bound H-particle should not exist.Comment: 10 pages, Invited talk given at International Conference on Hypernuclear and Strange Particle Physics (HYP97, Brookhaven National Laboratory, October 13-18, 1997, USA), to appear in Nuclear Physics

Kvazilastično izbijanje mezona iz nukleona. Razvoj i budućnost

The electroproduction of pions and kaons at the kinematics of quasi-elastic knockout is a powerful tool for investigation of mesonic cloud. A model of scalar qq¯ ( 3P0) fluctuation in the non-trivial QCD vacuum is used to calculate pion and kaon momentum distributions in the channels N→B+π, B = N, ∆, N∗ , N∗∗, and N→Y + K, Y=Λ, Σ0.Elektrotvorba piona i kaona u uvjetima kvazielastičnog izbijanja je moćna metoda za istraživanje elektronskog oblaka. Primijenili smo model skalarnih fluktuacija qq¯ ( 3P0) u netrivijalnom QCD vakuumu radi računanja raspodjela impulsa piona i kaona u kanalima N→B+π, B = N, ∆, N∗ , N∗∗, i N→Y + K, Y=Λ, Σ0

Microscopics of meson degrees of freedom in nucleons and mesons in nuclei - what can be seen in the process of quasielastic knockout of mesons by high-energy electrons

Developed earlier concept of quasielastic knock out of pions from nucleons by high-energy electrons is propounded as a tool for checking microscopical model ($^3P_0$ - fluctuation) for decay of N to different channels $\pi+B$ and Preparata model of nucleus structure.Comment: 6 pages, 5 figures, Talk given at 16 Baldin Symposium in June 200

Kvazilastično izbijanje mezona iz nukleona. Razvoj i budućnost

The electroproduction of pions and kaons at the kinematics of quasi-elastic knockout is a powerful tool for investigation of mesonic cloud. A model of scalar qq¯ ( 3P0) fluctuation in the non-trivial QCD vacuum is used to calculate pion and kaon momentum distributions in the channels N→B+π, B = N, ∆, N∗ , N∗∗, and N→Y + K, Y=Λ, Σ0.Elektrotvorba piona i kaona u uvjetima kvazielastičnog izbijanja je moćna metoda za istraživanje elektronskog oblaka. Primijenili smo model skalarnih fluktuacija qq¯ ( 3P0) u netrivijalnom QCD vakuumu radi računanja raspodjela impulsa piona i kaona u kanalima N→B+π, B = N, ∆, N∗ , N∗∗, i N→Y + K, Y=Λ, Σ0