29225985
Fission of heavy nuclei induced by stopped antiprotons. I. Inclusive characteristics of fission fragments.
Antiproton-induced fission has been investigated with a novel double-arm fission fragment spectrometer. Inclusive distributions of total mass, individual mass, and total kinetic energy of the fragments, and of the momentum of the fissioning nucleus, were measured. A dynamical model which takes into account all stages of [ital [bar p]]-induced fission (atomic cascade, intranuclear cascade, evaporation cascade, fission of compound nucleus, evaporation from fission fragments) was formulated for the first time. In particular, the dynamics of the descent of fissioning nuclei from saddle point to scission point are described by the diffusion model. The data on [ital [bar p]]-induced fission were analyzed in the framework of this model and good agreement between experiment and theory was obtained.
40381102
Interaction of stopped antiprotons with copper.
A natural Cu target was irradiated with the antiproton beam from the Low Energy Antiproton Ring facility at CERN. The 105 MeV/[ital c] [ital [bar p]] beam was completely slowed down inside a thick target producing many radioactive products. Starting shortly after the irradiation and continuing for about one year, this residual activity was counted using off-line gamma-ray spectroscopy techniques. The yields of 40 radioactive reaction products were determined. The charge dispersion and complete mass yield distribution were deduced using a well-established fitting procedure. The shape of the mass yield and, in particular, the average number of removed nucleons, the dispersion of the mass distribution, and its logarithmic slope characterize the average energy deposited during the antiproton-nucleus interaction. We compare these quantities with similar data gathered for other projectiles interacting with natural Cu targets. These comparisons indicate that the average excitation energy of the system formed after the stopped antiproton annihilation is similar to the average excitation energy following 2-GeV proton interaction with Cu nuclei. The observed mass distribution is also compared with the intranuclear cascade calculations.
43299016
Wormhole effect on the superstring axion.
Wormhole solutions can arise from the third-rank field strength ${H}_{\ensuremath{\mu}\ensuremath{\nu}\ensuremath{\rho}}$ which has a gluon anomaly. The superstring axion has this property. The effect of these wormholes on axion cosmology is studied. To save the superstring axion energy-density problem, \ensuremath{\theta}\ifmmode\bar\else\textasciimacron\fi{} is \ensuremath{\sim}${10}^{\mathrm{\ensuremath{-}}3}$ or ${\ensuremath{\Lambda}}_{0}^{1/4}$ is \ensuremath{\sim}10 keV at the QCD chiral-symmetry-breaking scale.
29930984
Interferometers and decoherence matrices
It is shown that the Lorentz group is the natural language for two-beam interferometers if there are no decoherence effects. This aspect of the interferometer can be translated into six-parameter representations of the Lorentz group, as in the case of polarization optics where there are two orthogonal components of one light beam. It is shown that there are groups of transformations which leave the coherency or density matrix invariant, and this symmetry property is formulated within the framework of Wigner's little groups. An additional mathematical apparatus is needed for the transition from a pure state to an impure state. Decoherence matrices are constructed for this process, and their properties are studied in detail. Experimental tests of this symmetry property are possible.
46735209
Linear canonical transformations of coherent and squeezed states in the Wigner phase space. II. Quantitative analysis.
Il est possible de calculer les valeurs d'expectation et les probabilites de transition a partir de la fonction de distribution phase-espace de Wigner. Sur la base des proprietes de transformation canonique de la fonction de Wigner, n developpe un algorithme pour calculer ces quantites en optique quantique, pour des etats coherents et compresses
45178947
Monojets from family unification.
Any model in which the neutrino mass matrix violates the Glashow-Iliopoulos-Maiani mechanism can give monojets. The Z can decay into one heavy and one light neutrino, with the heavier neutrino decaying into a jet. If the heavier neutrino is sufficiently light, this mechanism has not been ruled out by recent searches at PEP and PETRA for monojet signatures. Such monojets arise naturally in the SO(18) model of family unification. In this model we predict additional unusual events, which result from the purely leptonic decay of the heavier neutrino.
317645
Fermion doubling and a natural solution of the strong CP problem.
We suggest the fermion doubling for all quarks and leptons. It is a generalization of the neutrino doubling of the seesaw mechanism. The new quarks and leptons are SU(2) singlets and carry the electromagnetic charges of their lighter counterparts. An SU(3) [ital anomaly[minus]free] [ital global] [ital symmetry] or a discrete symmetry can be introduced to restrict the Yukawa couplings. The form of mass matrix belongs to that of Nelson and Barr. The weak [ital CP] violation of the Kobayashi-Maskawa form is obtained through the spontaneous breaking of [ital CP] symmetry at the high energy scale. The strong [ital CP] solution is through a specific form of the mass matrix. At low energy, the particle content is the same as in the standard model. For a model with a global symmetry, in addition, there exists a massless Majoron.