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Register a new userPolarization Phenomena in Fragmentation of Deuterons to Pions and Non-Nucleon Degrees of Freedom in the Deuteron
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The fragmentation of deuterons into pions emitted forward in the kinematic region forbidden for free nucleon-nucleon collisions is analyzed. It is shown that the inclusion of the non-nucleon degrees of freedom in a deuteron allows to describe the experimental data about inclusive pion spectrum rather satisfactory and improves the description of data concerning the deuteron analyzing power T_{20}. The experimental data show the positive sign and very small values, less than 0.2, of T_{20} what cant be reproduced by the calculations ignoring these degrees of freedom.
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It is shown that the magnitude of tensor polarization of the deuteron beam, which arises owing to the spin dichroism effect, depends appreciably on the angular width of the detector that registers the deuterons transmitted through the target. Even when the angular width of the detector is much smaller than the mean square angle of multiple Coulomb scattering, the beams tensor polarization depends noticeably on rescattering. When the angular width of the detector is much larger than the mean square angle of multiple Coulomb scattering (as well as than the characteristic angle of elastic nuclear scattering), tensor polarization is determined only by the total reaction cross sections for deuteron-nucleus interaction, and elastic scattering processes make no contribution to tensor polarization.
The existing experimental data for the deuteron charge radius are discussed. The data of elastic electron scattering are inconsistent with the value obtained in a recent atomic physics experiment. Theoretical predictions based on a nonrelativistic description of the deuteron with realistic nucleon-nucleon potentials and with a rather complete set of meson-exchange contributions to the charge operator are presented. Corrections arising from the quark-gluon substructure of the nucleon are explored in a nonrelativistic quark model; the quark-gluon corrections, not accounted for by meson exchange, are small. Our prediction for the deuteron charge radius favors the value of a recent atomic physics experiment.
General expressions for the unpolarized differential cross section and for various polarization observables in the coherent pseudoscalar meson photo- and electroproduction on the deuteron target have been obtained in one-photon-exchange approximation. The spin structure of the matrix element is explicitly derived in terms of structure functions. The correspondence with the helicity amplitudes is given. The polarization effects have been investigated for the case of a longitudinally polarized electron beam and vector or tensor polarized deuteron target. The polarization (vector or tensor) of the scattered deuteron for the case of unpolarized or a longitudinally polarized electron beam is also considered. In the case of the photoproduction reaction, we consider linearly, circularly or elliptically polarized photon beam. Numerical estimations have been done for the unpolarized differential cross section and for some polarization observables.
We consider the quantization of chiral solitons with baryon number $B>1$. Classical solitons are obtained within the framework of a variational approach. From the form of the soliton solution it can be seen that besides the group of symmetry describing transformations of the configuration as a whole there are additional symmetries corresponding to internal transformations. Taking into account the additional degrees of freedom leads to some sort of spin alignment for light nuclei and gives constraints on their spectra.
The intranuclear cascade model INCL (Li`ege Intranuclear Cascade) is now able to simulate spallation reactions induced by projectiles with energies up to roughly 15 GeV. This was made possible thanks to the implementation of multipion emission in the NN, $Delta$N and $pi$N interactions. The results obtained with reactions on nuclei induced by nucleons or pions gave confidence in the model. A next step will be the addition of the strange particles, $Lambda$, $Sigma$ and Kaons, in order to not only refine the high-energy modeling, but also to extend the capabilities of INCL, as studying hypernucleus physics. Between those t
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