120353647
Can the family group be a global symmetry
Abstract We consider the possibility that the family group may be a spontaneously broken continuous global symmetry. In the context of grand unification, the couplings of the associated Goldstone bosons to fermions can be sufficiently suppressed so as to satisfy the phenomenological bounds. For a maximal family symmetry this requires a large number of Higgs fields.
120357004
Neutral lepton mass matrix
Spinor particles are characterized by their transformation properties under the Lorentz group. (AIP)
123621838
No massless scalar adjoints for N=1, D=4 heterotic strings in the free fermionic formulation
Abstract Using the free fermionic formulation of four-dimensional heterotic superstrings with N =1 spacetime supersymmetry, we prove that the massless spectrum does not contain that transform as the adjoint representation of the gauge group. Some implications for model building are also discussed. We also show that no higher dimensional massless representations occur except possibly when the gauge group has an SU(9) or SO(16) factor. We discuss these two cases and their connection to the possible appearance of an E 8 factor.
120385277
A left-right symmetric model with a useful global symmetry☆
Abstract A simple left-right symmetric model is presented in which a global symmetry prevents neutrinos from acquiring a mass, avoids flavor changing neutral current effects and predicts the existence, in one case, of an absolutely stable quark or lepton.
123523374
Nonstandard fermion mass matrices and nucleon decay
We discuss how nonstandard fermion mass matrices (with hierarchical eigenvalues) lead to mixing effects in nucleon decay which can enhance the branching ratios of naively unexpected decay modes, and could suppress the rates for N..-->..e/sup +/+ nonstrange hadron(s).
121122277
Fermion masses and phenomenology in SO(10) or SU(5) superstring compactifications
Abstract Symmetry breaking patterns and phenomenology of the SO(10) and SU(5) compactifications of the E 8 ×E 8 ′ heterotic superstring recently proposed by Witten are examined with regard to the fermion mass matrix. Under some circumstances there exist constraints due to the presence of relatively light charged leptons.
118498735
Dust ejection from planetary bodies by temperature gradients: Laboratory experiments
Abstract Laboratory experiments show that dusty bodies in a gaseous environment eject dust particles if they are illuminated. We find that even more intense dust eruptions occur when the light source is turned off. We attribute this to a compression of gas by thermal creep in response to the changing temperature gradients in the top dust layers. The effect is studied at a light flux of 13 kW/m 2 and 1 mbar ambient pressure. The effect is applicable to protoplanetary disks and Mars. In the inner part of protoplanetary disks, planetesimals can be eroded especially at the terminator of a rotating body. This leads to the production of dust which can then be transported towards the disk edge or the outer disk regions. The generated dust might constitute a significant fraction of the warm dust observed in extrasolar protoplanetary disks. We estimate erosion rates of about 1 kg s −1 for 100 m parent bodies. The dust might also contribute to subsequent planetary growth in different locations or on existing protoplanets which are large enough not to be susceptible to particle loss by light induced ejection. Due to the ejections, planetesimals and smaller bodies will be accelerated or decelerated and drift outward or inward, respectively. The effect might also explain the entrainment of dust in dust devils on Mars, especially at high altitudes where gas drag alone might not be sufficient.