Establishing the resonance spectrum of the nucleon with accuracy would provide important new information about the dynamics and degrees of freedom of its constituents. The spectrum and properties of nucleon resonances are a fundamental test of the emerging predictions from Lattice QCD calculations and will guide refinements to QCD-based phenomenological models. Pion photoproduction is an excell...

We evaluate widths and shifts of pionic atoms using a theoretical microscopical potential in which the pion decay constant fπ is changed by the medium fπ(ρ) one, predicted by many different approaches. We show that the results obtained for shifts and widths are worse than if the correction is not implemented. Only in the case where one implements the modification in the real part of the s−wave ...

Recent theoretical investigations of high energy nucleon-nucleon collisions1) support the two-center model of multiple meson production as discussed by Ciok, et al.2 ) . To facilitate a prediction of the most probable distribution of shower particles as a function of laboratory energy, Farley's kinematical treatment of the "two-fireball" model is employed 3). A statistical determination of the ...

We calculate in (two-loop) chiral perturbation theory the local NN-potentials generated by certain classes of three-pion exchange diagrams. We stress that the chiral 3πN N-contact vertex depends on the particular choice of the interpolating pion-field and therefore one has to consider representation invariant classes of diagrams by supplementing graphs involving the chiral 4π-vertex. We find th...

Measurement of Bose-Einstein correlations in the production of like-signed pion pairs has been made with the AMY detector at TRISTAN. An event sample of 10120 hadronic events with ranging between 50 to 61 GeV was used. These measurements indicate a strength of the enhancement of ? = 0.61M.07, with a typical correlation size of Ro = 1.16±.08 fm. This value of ? is consistent with measurem...

In addition to optimal conditions, invariant laws of Lorentz, parity and time reversal are imposed to find the relation between observables (spin rotation parameters) and bilinear combination of helicity amplitudes in pion-proton elastic scattering at 6.0 GeV/c. By normalizing the differential cross-section to unity, the magnitudes of helicity amplitudes and the angle between them are dete...

We present a study of coherent pion production in neutrino-nucleus interactions using the formalism based on partially conserved axial current theorem which connects cross section to pion-nucleus elastic scattering section. Pion-nucleus is calculated Glauber model takes three inputs, nuclear densities, pion-nucleon and $\alpha_{\pi N}$ ratio real imaginary part $\pi N$ forward amplitude, for pa...

Using Dyson–Schwinger equations, the nucleon propagator is analyzed nonperturbatively in a field–theoretical model for the pion–nucleon interaction. Infinities are circumvented by using pion–nucleon form factors which define the physical scale. It is shown that the correct, finite, on–shell nucleon renormalization is important for the value of the mass–shift and the propagator. For physically a...

From recent charge exchange measurements in the extreme forward direction, an independent and precise determination of the pion nucleon coupling constant is possible. This determination has reopened the debate on the value of this fundamental coupling constant of nuclear physics. Precise measurements of charge exchange observables at forward angles below 900 MeV/c would also give a better under...

Radiobiological measurements have been made under various conditions of muliport pion irradiation using the Stanford Medical Pion Generator (SMPG). Chinese hamster cells (HA-1) were suspended in a tissue-equivalent 25% gelatin/medium solution. Hypoxic and aerobic HA-1 cells were irradiated simultaneously in a cylindrical water tank at either 4 or 16 degrees C. Irradiation at the focus of 60 con...