Quasifree Pion Electroproduction from Nuclei in the Δ\Delta Region

We present calculations of the reaction $A(e,e^\prime \pi N)B$ in the distorted wave impulse approximation. The reaction allows for the study of the production process in the nuclear medium without being obscured by the details of nuclear transition densities. First, a pion electroproduction operator suitable for nuclear calculations is obtained by extending the Blomqvist-Laget photoproduction operator to the virtual photon case. The operator is gauge invariant, unitary, reference frame independent, and describes the existing data reasonably well. Then it is applied in nuclei to predict nuclear cross sections under a variety of kinematic arrangements. Issues such as the effects of gauge-fixing, the interference of the $\Delta$ resonance with the background, sensitivities to the quadrupole component of the $\Delta$ excitation and to the electromagnetic form factors, the role of final-state interactions, are studied in detail. Methods on how to experimentally separate the various pieces in the coincidence cross section are suggested. Finally, the model is compared to a recent SLAC experiment.Comment: 27 pages in REVTEX, plus 22 PS figures embedded using psfig.sty (included), uuencode

Определение области нестабильных параметров системы микрогравитации, гарантирующих допустимую степень устойчивости

На основании найденных значений интервалов коэффициентов характеристического полинома и их зависимостей от нестабильных параметров составляется система неравенств, решение которой дает границы искомой области.Based on the found values of the intervals of the coefficients of the characteristic polynomial and their dependences on unstable parameters, a system of inequalities is drawn up, the solution of which gives the boundaries of the desired region

Measurement of the recoil polarization in the p (\vec e, e' \vec p) pi^0 reaction at the \Delta(1232) resonance

The recoil proton polarization has been measured in the p (\vec e,e'\vec p) pi^0 reaction in parallel kinematics around W = 1232 MeV, Q^2 = 0.121 (GeV/c)^2 and epsilon = 0.718 using the polarized c.w. electron beam of the Mainz Microtron. Due to the spin precession in a magnetic spectrometer, all three proton polarization components P_x/P_e = (-11.4 \pm 1.3 \pm 1.4) %, P_y = (-43.1 \pm 1.3 \pm 2.2) %, and P_z/P_e = (56.2 \pm 1.5 \pm 2.6) % could be measured simultaneously. The Coulomb quadrupole to magnetic dipole ratio CMR = (-6.4\pm 0.7_{stat}\pm 0.8_{syst}) % was determined from P_x in the framework of the Mainz Unitary Isobar Model. The consistency among the reduced polarizations and the extraction of the ratio of longitudinal to transverse response is discussed.Comment: 5 pages LaTeX, 1 table, 2 eps figure

Leptonic Production of Baryon Resonances

In these lectures, the author focuses on the electromagnetic transition between non-strange baryon states. This sector received much attention in the early 1970's after the development of the first dynamical quark models. However, experimental progress was slow, partly because of the low rates associated with electromagnetic interactions, and partly because of the lack of guidance by theoretical models that went beyond the simplest quark models. It was also difficult for experiments to achieve the precision needed for a detailed analysis of the entire resonance region in terms of the fundamental photocoupling amplitudes over a large range in momentum transfer