39663516
Dynamical axion.
18138135
Neutrino masses from discrete gauge symmetries
Abstract We investigate a model with an extra Z 2 gauge symmetry in the Standard Model. The symmetry gives a structure to the mass matrix for the neutrinos. With two extra Higgs singlets and two extra singlet right-handed neutrinos we can build a model that fits the requirements of the MSW solution of the Solar neutrino problem. With a third singlet right-handed neutrino it is also possible to have a 10 eV neutrino.
119883211
Conflicts between B-violating phenomena in supergravity models
Abstract We show that there is an incompatibility between matter stability and cosmological baryon production in standard N = 1 supergravity models. This discrepancy emerges from the bound on the reheating temperature T rh ⩽ 10 10 GeV which comes from the restriction on the gravitino decay after inflation. Some weird possibilities to bypass the controversy are also analyzed.
15739165
SO(10)-like Superstring Standard Model with R-parity from the Heterotic String
We construct a supersymmetric standard model in the context of the Z_{12-I} orbifold compactification of the E_8 x E_8' heterotic string theory. The gauge group is SU(3)_c x SU(2)_L x U(1)_Y x U(1)^4 x [SO(10) x U(1)^3]' with sin^2\theta_W = 3/8. We obtain three families of SO(10) spinor-like chiral matter states, and Higgs doublets. All other extra states are exactly vector-like under the standard model gauge symmetry. There are numerous standard model singlets, many of which get VEVs such that only the standard model gauge symmetry survives and desired Yukawa couplings can be generated at lower energies. In particular, all vector-like exotic states achieve superheavy masses and the R-parity can be preserved.
119316975
GMSB at a stable vacuum and MSSM without exotics from heterotic string
Abstract We show that it is possible to introduce the confining hidden sector gauge group SU ( 5 ) ′ with the chiral matter 10 0 ′ plus 5 ¯ 0 ′ , which are neutral under the standard model gauge group, toward a gauge mediated supersymmetry breaking (GMSB) in a Z 12 − I orbifold compactification of E 8 × E 8 ′ heterotic string. Three families of MSSM result without exotics. We also find a desirable matter parity P (or R-parity) assignment. We note that this model contains the spectrum of the Lee–Weinberg model which has a nice solution of the μ problem.
14574575
Effective Gauss-Bonnet interaction in Randall-Sundrum compactification
The effective gravitational interaction below the Planck scale in the Randall-Sundrum world is shown to be the Gauss-Bonnet term. In this theory we find that there exists another static solution with a positive bulk cosmological constant. Also, there exist solutions for a positive visible sector cosmological constant, which is needed for a later Friedmann-Robertson-Walker universe.
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.
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.}
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.
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.
37815893
Covariant phase-space representation for localized light waves.