S.-H.H. Tye

Three-Family SO(10) Grand Unification in String Theory.

The construction of a supersymmetric SO(10) grand unification with 5 left-handed and 2 right-handed families in the four-dimensional heterotic string theory is presented. The model has one SO(10) adjoint Higgs field. The SO(10) current algebra is realized at level 3. {copyright} {ital 1996 The American Physical Society.}

Asymmetric non-Abelian orbifolds and model building.

The rules for the free fermionic string model construction are extended to include general non-Abelian orbifold constructions that go beyond the real fermionic approach. This generalization is also applied to the asymmetric orbifold rules recently introduced. These non-Abelian orbifold rules are quite easy to use. Examples are given to illustrate their applications. {copyright} {ital 1996 The American Physical Society.}

Kac and new determinants for fractional superconformal algebras.

We derive the Kac and new determinant formulas for an arbitrary (integer) level [ital K] fractional superconformal algebra using the BRST cohomology techniques developed in conformal field theory. In particular, we reproduce the Kac determinants for the Virasoro ([ital K]=1) and superconformal ([ital K]=2) algebras. For [ital K][ge]3 there always exist modules where the Kac determinant factorizes into a product of more fundamental new determinants. Using our results for general [ital K], we sketch the nonunitarity proof for the SU(2) minimal series; as expected, the only unitary models are those already known from the coset construction. We apply the Kac determinant formulas for the spin 4/3 parafermion current algebra (i.e., the [ital K]=4 fractional superconformal algebra) to the recently constructed three-dimensional flat Minkowski space-time representation of the spin-4/3 fractional superstring.

Tree scattering amplitudes of the spin-4/3 fractional superstring. I. The untwisted sectors.

Scattering amplitudes of the spin-4/3 fractional superstring are shown to satisfy spurious state decoupling and cyclic symmetry (duality) at tree-level in the string perturbation expansion. This fractional superstring is characterized by the spin-4/3 fractional superconformal algebra---a parafermionic algebra studied by Zamolodchikov and Fateev involving chiral spin-4/3 currents on the world-sheet in addition to the stress-energy tensor. Examples of tree scattering amplitudes are calculated in an explicit c=5 representation of this fractional superconformal algebra realized in terms of free bosons on the string world-sheet. The target space of this model is three-dimensional flat Minkowski space-time with a level-2 Kac-Moody so(2,1) internal symmetry, and has bosons and fermions in its spectrum. Its closed string version contains a graviton in its spectrum. Tree-level unitarity (i.e., the no-ghost theorem for space-time bosonic physical states) can be shown for this model. Since the critical central charge of the spin-4/3 fractional superstring theory is 10, this c=5 representation cannot be consistent at the string loop level. The existence of a critical fractional superstring containing a four-dimensional space-time remains an open question.

The Properties of Scalar - Quark Bound States

Abstract We discuss the (static) potential for scalar quark bound states, their leptonic and hadronic decays and their radiative transitions.

NEUTRAL B MESON DECAY AND THE SEARCH FOR HYBRID MESONS

Abstract We discuss the possibility that the decay of the neutral B mesons via a non-spectator mechanism might have a significant branching fraction into ( q q g ) states. The lightest such hybrid mesons would be recognizable as narroe state of mass 1.6 ± 0.4 GeV c 2 decaying predominantly into hadrons containing strange quarks.

Alternative formulations of first quantized covariant string action

Abstract In the covariant formulation of the first quantized action for a string propagating in Minkowski space it is natural to introduce a field (called dualbein) which is a worldsheet vector as well as a spacetime vector. The dualbein is a logical generalization of the zweibein. In terms of the dualbein field we construct new covariant actions for the bosonic strings and the superstrings. The casev of massless superparticles is also discussed.

Measuring the triple-gluon vertex

Abstract The triple-gluon vertex can be measured from the gluon jet spread using the energy-cone distribution functions.