121480751
Fractional charges, monopoles, and peculiar photons
A grand unified model is proposed which incorporates a ''peculiar'' photon in addition to the familiar photon. The model is constructed to reconcile the possible observations of fractional charges and monopoles. One way to have the weak-mixing-angle prediction agree with the phenomenological value is to require the peculiar photon to couple more strongly than the regular photon.
85558805
Cosmological constraints on heavy weakly interacting fermions
Abstract The masses and lifetimes of very heavy weakly interacting fermions which appear in many grand unified gauge models are constrained by the requirement that their decays in the hot big bang early universe should not generate excessive entropy which would dilute n B / n γ below its observed value.
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.
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.
120861006
PECCEI-QUINN SYMMETRIES WITHOUT DOMAINS
In general, the unbroken discrete subgroup of a Peccei-Quinn symmetry gives rise to a domain problem: the formation of unacceptable domain walls in the course of the evolution of the early universe. In this paper, we construct an SU(5) model in which the unbroken discrete subgroup of a Peccei-Quinn symmetry is a trivial Z/sub 1/. That means that there is no domain problem for this model. It is pointed out that in models with more than one global U(1) symmetry it is easy to achieve a solution to the domain problem.
120357004
Neutral lepton mass matrix
Spinor particles are characterized by their transformation properties under the Lorentz group. (AIP)
118943918
Real-Time Detection of Gravitational Microlensing
Real-time detection of microlensing has moved from proof of concept in 1994 (Udalski et al. 1994a, Alcock et al.1994) to a steady stream of events this year. Global dissemination of these events by the MACHO and OGLE collaborations has made possible intensive photometric and spectroscopic follow up from widely dispersed sites confirming the microlensing hypothesis (Benetti 1995). Improved photometry and increased temporal resolution from follow up observations greatly increases the possibility of detecting deviations from the standard point-source, point-lens, inertial motion microlensing model. These deviations are crucial in understanding individual lensing systems by breaking the degeneracy between lens mass, position and velocity. We report here on GMAN (Global Microlensing Alert Network), the coordinated follow up of MACHO alerts.