26549212
Fission of heavy nuclei induced by stopped antiprotons. II. Correlations between fission fragments.
Antiproton-induced fission has been investigated with a novel double-arm fission fragment spectrometer. The correlations in mass, energy, and velocity between two fragments were measured. The dependence of total kinetic energy, velocity, momentum of the fissioning nucleus, and momentum of the fission fragments on the mass loss was deduced and analyzed in the framework of the dynamical statistical model. This model takes into account all stages before, during and after {ital {bar p}}-induced fission (atomic cascade, intranuclear cascade, evaporation cascade, fission of the compound nucleus, evaporation from the fission fragments). The mass loss was used as a measure of the excitation energy to classify the fission events according to the corresponding excitation energies. Some discrepancies between the model calculation and the experiment show the important role of dissipative effects in the {ital {bar p}}-induced fission process. {copyright} {ital 1996 The American Physical Society.}
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.
37465442
Fermion mass matrix and strong CP solution in SU(5).
A global U(1)/sub A/ symmetry is used to solve both the fermion-mass-hierarchy problem and the strong CP problem. A domain-wall-free invisible-axion model requires heavy fermions at the axion scale. The dominant contribution to the off-diagonal elements of the fermion mass matrix comes from the small vacuum expectation value of superheavy scalar doublets, which is guaranteed by the Peccei-Quinn symmetry.
3075702
New effective Feynman-like rules for the multi-Regge QCD asymptotics of inclusive multijet production.
New effective Feynman-like rules are defined for inclusive multijet cross sections in the multi-Regge regime. The solution of the Balitskii-Fadin-Kuraev-Lipatov (BFKL) equation is used as a starting point. The resulting rules involve conformal weight and rapidity as a momentum and a coordinate, respectively, and are translation invariant in the coordinates. We use the effective rules to calculate ultrahigh-energy asymptotics of inclusive multijet production. The dependence on the parton densities occurs only in the overall normalization of the asymptotic cross sections. {copyright} {ital 1996 The American Physical Society.}
40702960
Covariant phase-space representation and overlapping distribution functions.
The Lorentz deformation property of the phase-space distribution function is studied for harmonic oscillators. The overlap effect of two distribution functions is discussed in detail. It is shown that the Lorentz deformation of the phase-space distribution is responsible for the polynomial cutoff behavior of the proton form factor in the harmonic-oscillator quark model.
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.
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